Energy Management

RENEWABLE ENERGY SCENARIO IN INDIA
A generalised overview...
ENERGY SCENE IN INDIA
Anything tangible or intangible, that costs money is evaluated very carefully and used equally carefully in India. This means expenses are controlled and kept as low as possible. The scenario in energy consumption in India is no different. It is not surprising that the per capita energy consumption figures are very low inspite of high rate of development now taking place. The per capita consumption in India is in the region of 400 KWH per annum. In the ninth five year plan (1997-2002) energy strategy is divided into short term strategy, medium strategy and long term strategy.

SHORT TERM STRATEGY
• Administered pricing mechanism • Institutional reforms to be consolidated for deregulation • Optimum utilization of existing assets • Production systems to be made efficient, transmission and distribution losses to be reduced • R&D transfer of technologies to be promoted • Energy efficiency improvement in accordance with national and socio-economic and environmental priorities • Energy efficiency and emission standards to be promoted • Labelling programmes for products • Adoption of energy efficient technologies in giant industries

MEDIUM AND LONG TERM STRATEGIES
• Demand management through greater conservation of energy, optimum fuel mix, increasing reliance on rail for movement of goods and passengers and shift to emphasis on utilizing mass movement and transport systems for public rather than private transports • Better urban planning to reduce need for energy in transport sector • Shift and emphasis to solar, wind, biomass energy sources • Emphasis on research and development, transfer and use of energy efficient technologies and practices in the supply and end-use sectors.

RENEWABLE ENERGY SCENARIO IN INDIA
India is blessed with an abundance of sunlight, water and biomass. Vigorous efforts during the past two decades are now bearing fruit as people in all walks of life are more aware of the benefits of renewable energy, especially decentralized energy where required in villages and in urban or semi-urban centers. India has the world’s largest programme for renewable energy. Government created the Department of Non-conventional Energy Sources (DNES) in 1982. In 1992 a full fledged Ministry of Non-conventional Energy Sources was established under the overall charge of the Prime Minister. The range of its activities cover • promotion of renewable energy technologies, • create an environement conducive to promote renewable energy technologies, • create an environment conducive for their commercialization, • renewable energy resource assessment, • research and development, • demonstration, • extension, • production of biogas units, solar thermal devices, solar photovoltaics, cookstoves, wind energy and small hydropower units.

Wind Power
India now ranks as a "wind superpower" with an installed wind power capacity of 1167 MW and about 5 billion units of electricity have been fed to the national grid so far. In progress are wind resource assessment programme, wind monitoring, wind mapping, covering 800 stations in 24 states with 193 wind monitoring stations in operations. Altogether 13 states of India have a net potential of about 45000 MW.

Solar Energy
Solar water heaters have proved the most popular so far and solar photovoltaics for decentralized power supply are fast becoming popular in rural and remote areas. More than 700000 PV systems generating 44 MW have been installed all over India. Under the water pumping programme more than 3000 systems have been installed so far and the market for solar lighting and solar pumping is far from saturated. Solar drying is one area which offers very good prospects in food, agricultural and chemical products drying applications.

SPV Systems

More than 700000 PV systems of capacity over 44MW for different applications are installed all over India. The market segment and usage is mainly for home lighting, street lighting, solar lanterns and water pumping for irrigation. Over 17 grid interactive solar photovoltaic generating more than 1400 KW are in operation in 8 states of India. As the demand for power grows exponentially and conventional fuel based power generating capacity grows arithmetically, SPV based power generation can be a source to meet the expected shortfall. Especially in rural, far-flung where the likelihood of conventional electric lines is remote, SPV power generation is the best alternative.

Solar Cookers
Government has been promoting box type solar cookers with subsidies since a long time in the hope of saving fuel and meeting the needs of the rural and urban populace. There are community cookers and large parabolic reflector based systems in operation in some places but solar cookers, as a whole, have not found the widespread acceptance and popularity as hoped for. A lot of educating and pushing will have to be put in before solar cookers are made an indispensable part of each household (at least in rural and semi-urban areas). Solar cookers using parabolic reflectors or multiple mirrors which result in faster cooking of food would be more welcome than the single reflector box design is what some observers and users of the box cookers feel.

Solar Water Heaters A conservative estimate of solar water heating systems installed in the country is estimated at over 475000 sq. mtrs of the conventional flat plate collectors. Noticeable beneficiaries of the programme of installation of solar water heaters so far have been cooperative dairies, guest houses, hotels, charitable institutions, chemical and process units, hostels, hospitals, textile mills, process houses and individuals. In fact in India solar water heaters are the most popular of all renewable energy devices. So where do we stand and where are we heading to?

Solar Photovoltaics in India
Begun as far back as in the mid 70’s solar photovoltaics programme of the Government of India is one of the largest in the World. While the rest of the world has progressed tremendously in production of basic silicon monocrystalline photoltaic cells, in India the major players are Central Electronics Ltd, BHEL, REIL and the other manufacturers of SPV modules are in fact assemblers sourcing the cells and carrying out assembly. Where this segment of basic manufacturing has not shown much growth in India and is unlikely also in the near future due to high costs involved in manufacturing monocrystalline silicon cells from scratch, the market is growing for SPV applications based products with the active encouragement of the government.

Electricity and social development go hand in hand. Rural areas of India are so far-flung that in some cases it is decided not to lay down conventional electricity lines due to the small populace to be served and high cost of laying lines. Conventional gensets are also not feasible due to recurring maintenance problems. The best solution under the circumstances is solar photovoltaic based systems to generate power, run irrigation pumping sets and home lighting and streetlights. In addition to offering subsidy on these products government is also offering training on PV technology, PV system designs and related fields. The programme of MNES comprises of promoting use of PV technology to provide lighting in villages in the form of : Community lighting systems Portable solar lanterns Capacity usually 1KW to 2.5 KW Small 10Wp SPV module connected to a 12V7AH battery lighting 7 W CFL lamp for 3 hours a day Built around a 75Wp SPV module charging a 100-130AH battery to run a 11W CFL lamp for dusk to dawn operation. Based on 35-50Wp SPV module, powering two CFLs each of 9 or 11W to work 4-5 hours per day. Some systems also incorporate facility to run a small TV set or a fan from the power supply. Typically 1KW DC motor based pumping for shallow pumping.

Street lights

Fixed home lighting systems

Water Pumping

Reliefs offered by government on SPV manufacturers and users of SPV based products : • • • • 100% depreciation in the first year of installation of the systems No excise duty for manufacturers Low import tariff for several raw materials and components Soft loans to users, intermediaries and manufacturers.

Entrepreneurs worldwide wishing to tap the Indian markets will find it a rewarding experience. A local partner helps.. So go on….spread the light..

Solar Water Heating Systems

Businesses and applications of solar water heating systems...?. ...click here

Guidelines for IREDA loan assistance... ...click here

This page provides basic information on the components and types of solar water heaters currently available and the economic and environmental benefits of owning a system. This could be helpful in selecting a system for your home or industry.

Solar water heaters are cost competitive in many applications when you account for the total energy costs over the life of the system. Although the initial cost of solar water heaters is higher than that of conventional water heaters, the fuel (sunshine) is free. Plus, they are environmentally friendly. To take advantage of these heaters, you must have an unshaded, south-facing location (a roof, for example) on your property.

These systems use the Sun to heat either water or a heat-transfer fluid, such as a water-glycol antifreeze mixture, in collectors generally mounted on a roof. The heated water is then stored in a tank similar to a conventional gas or electric water tank. Some systems use an electric pump to circulate the fluid through the collectors.

Solar water heaters can operate in any climate. Performance varies depending, in part, on how much solar energy is available at the site, but also on how cold the water coming into the system is. The colder the water, the more efficiently the system operates. In almost all climates, you will need a conventional backup system. In fact, many building codes require you to have a conventional water heater as the backup.

First Things First
Before investing in any solar energy system, it is more cost effective to invest in making your home more energy efficient. Taking steps to use less hot water and to lower the temperature of the hot water you use reduces the size and cost of your solar water heater.

Good first steps are installing low-flow showerheads or flow restrictors in shower heads and faucets, insulating your current water heater, and insulating any hot water pipes that pass through unheated areas. If you have no dishwasher, or your dishwasher is equipped with its own automatic water heater, lower the thermostat on your water heater to 120°F (49°C).

You'll also want to make sure your site has enough available sunshine to meet your needs efficiently and economically. Your local solar equipment dealer can perform a solar site analysis for you or show you how to do your own.

Remember: Local zoning laws or covenants may restrict where you can place your collectors. Check with your city, county, and homeowners association to find out about any restrictions.

Solar Water Heater Basics
Solar water heaters are made up of collectors, storage tanks, and, depending on the system, electric pumps.

There are basically three types of collectors: flatplate, evacuated-tube, and concentrating. A flatplate collector, the most common type, is an insulated, weatherproofed box containing a dark absorber plate under one or more transparent or translucent covers.

Evacuated-tube collectors are made up of rows of parallel, transparent glass tubes. Each tube consists of a glass outer tube and an inner tube, or absorber, covered with a selective coating that absorbs solar energy well but inhibits radiative heat loss. The air is withdrawn ("evacuated") from the space between the tubes to form a vacuum, which eliminates conductive and convective heat loss.

Concentrating collectors for residential applications are usually parabolic troughs that use mirrored surfaces to concentrate the sun's energy on an absorber tube (called a receiver) containing a heat-transfer fluid. For more information on solar collectors, contact EREC.

Most commercially available solar water heaters require a well-insulated storage tank. Many systems use converted electric water heater tanks or plumb the solar storage tank in series with the conventional water heater. In this arrangement, the solar water heater preheats water before it enters the conventional water heater.

Some solar water heaters use pumps to recirculate warm water from storage tanks through collectors and exposed piping. This is generally to protect the pipes from freezing when outside temperatures drop to freezing or below.

Types of Solar Water Heaters
Solar water heaters can be either active or passive. An active system uses an electric pump to circulate the heat-transfer fluid; a passive system has no pump. The amount of hot water a solar water heater produces depends on the type and size of the system, the amount of sun available at the site, proper installation, and the tilt angle and orientation of the collectors.

Solar water heaters are also characterized as open loop (also called "direct") or closed loop (also called "indirect"). An open-loop system circulates household (potable) water through the collector. A closed-loop system uses a heat-transfer fluid (water or diluted antifreeze, for example) to collect heat and a heat exchanger to transfer the heat to household water.

Active Systems
Active systems use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors. They are usually more expensive than passive systems but are also more efficient. Active systems are usually easier to retrofit than passive systems because their storage tanks do not need to be installed above or close to the collectors. But because they use electricity, they will not function in a power outage. Active systems range in price from about $2,000 to $4,000 installed.

Open-Loop Active Systems
Open-loop active systems use pumps to circulate household water through the collectors. This design is efficient and lowers operating costs but is not appropriate if your water is hard or acidic because scale and corrosion quickly disable the system.

These open-loop systems are popular in nonfreezing climates such as Hawaii. They should never be installed in climates that experience freezing temperatures for sustained periods. You can install them in mild but occasionally freezing climates, but you must consider freeze protection.

Recirculation systems are a specific type of open-loop system that provide freeze protection. They use the system pump to circulate warm water from storage tanks through collectors and exposed piping when temperatures approach freezing. Consider recirculation systems only where mild freezes occur once or twice a year at most. Activating the freeze protection more frequently wastes electricity and stored heat.

Of course, when the power is out, the pump will not work and the system will freeze. To guard against this, a freeze valve can be installed to provide additional protection in the event the pump doesn't operate. In freezing weather, the valve dribbles warmer water through the collector to prevent freezing. Consider recirculation systems only where mild freezes occur once or twice a year at most. Activating the freeze protection more frequently wastes electricity and stored heat.

Of course, when the power is out, the pump will not work and the system will freeze. To guard against this, a freeze valve can be installed to provide additional protection in the event the pump doesn't operate. In freezing weather, the valve dribbles warmer water through the collector to prevent freezing.

Closed-Loop Active Systems
These systems pump heat-transfer fluids (usually a glycol-water antifreeze mixture) through collectors. Heat exchangers transfer the heat from the fluid to the household water stored in the tanks.

Double-walled heat exchangers prevent contamination of household water. Some codes require double walls when the heat-transfer fluid is anything other than household water.

Closed-loop glycol systems are popular in areas subject to extended freezing temperatures because they offer good freeze protection. However, glycol antifreeze systems are a bit more expensive to buy and install, and the glycol must be checked each year and changed every 3 to 10 years, depending on glycol quality and system temperatures.

Drainback systems use water as the heat-transfer fluid in the collector loop. A pump circulates the water through the collectors. The water drains by gravity to the storage tank and heat exchanger; there are no valves to fail. When the pumps are off,the collectors are empty, which assures freeze protection and also allows the system to turn off if the water in the storage tank becomes too hot.

Pumps in Active Systems
The pumps in solar water heaters have low power requirements, and some companies now include direct current (DC) pumps powered by small solar-electric (photovoltaic, or PV) panels. PV panels convert sunlight into DC electricity. Such systems cost nothing to operate and continue to function during power outages.

Passive Systems
Passive systems move household water or a heat-transfer fluid through the system without pumps. Passive systems have no electric components to break. This makes them generally more reliable, easier to maintain, and possibly longer lasting than active systems.

Passive systems can be less expensive than active systems, but they can also be less efficient. Installed costs for passive systems range from about $1,000 to $3,000, depending on whether it is a simple batch heater or a sophisticated thermosiphon system.

Batch Heaters
Batch heaters (also known as "bread box" or integral collector storage systems) are simple passive systems consisting of one or more storage tanks placed in an insulated box that has a glazed side facing the sun. Batch heaters are inexpensive and have few components—in other words, less maintenance and fewer failures. A batch heater is mounted on the ground or on the roof (make sure your roof structure is strong enough to support it). Some batch heaters use "selective" surfaces on the tank(s). These surfaces absorb sun well but inhibit radiative loss.

In climates where freezing occurs, batch heaters must either be protected from freezing or drained for the winter. In well-designed systems, the most vulnerable components for freezing are the pipes, if located in uninsulated areas, that lead to the solar water heater. If these pipes are well insulated, the warmth from the tank will prevent freezing. Certified systems clearly state the temperature level that can cause damage. In addition, you can install heat tape (electrical plug-in tape to wrap around the pipes to keep them from freezing), insulate exposed pipes, or both. Remember, heat tape requires electricity, so the combination of freezing weather and a power outage can lead to burst pipes. If you live in an area where freezing is infrequent, you can use plastic pipe that does not crack or burst when it freezes. Keep in mind, though, that some of these pipes can't withstand unlimited freeze/thaw cycles before they crack.

Thermosiphon Systems
A thermosiphon system relies on warm water rising, a phenomenon known as natural convection, to circulate water through the collectors and to the tank. In this type of installation, the tank must be above the collector. As water in the collector heats, it becomes lighter and rises naturally into the tank above. Meanwhile, cooler water in the tank flows down pipes to the bottom of the collector, causing circulation throughout the system. The storage tank is attached to the top of the collector so that thermosiphoning can occur. These systems are reliable and relatively inexpensive but require careful planning in new construction because the water tanks are heavy. They can be freeze-proofed by circulating an antifreeze solution through a heat exchanger in a closed loop to heat the household water.

Sizing Your System
Just as you have to choose a 30-, 40-, or 50-gallon (114-, 151-, or 189-liter) conventional water heater, you need to determine the right size solar water heater to install. Sizing a solar water heater involves determining the total collector area and the storage volume required to provide 100% of your household's hot water during the summer. Solar-equipment experts use worksheets or special computer programs to assist you in determining how large a system you need.

Solar storage tanks are usually 50-, 60-, 80-, or 120-gallon (189-, 227-, 303-, or 454-liter) capacity. A small (50 to 60 gallon) system is sufficient for 1 to 3 people, a medium (80-gallon) system is adequate for a 3- or 4-person household, and a large (120-gallon) system is appropriate for 4 to 6 people.

A rule of thumb for sizing collectors: allow about 20 square feet (about 2 square meters) of collector area for each of the first two family members and 8 square feet (0.7 square meter) for each additional family member if you live in the Sun Belt. Allow 12 to 14 additional square feet (1.1 to 1.3 square meters) per person if you live in the northern United States.

A ratio of at least 1.5 gallons (5.7 liters) of storage capacity to 1 square foot (0.1 square meter) of collector area prevents the system from overheating when the demand for hot water is low. In very warm, sunny climates, experts suggest that the ratio should be at least 2 gallons (7.6 liters) of storage to 1 square foot (0.1 square meter) of collector area. For example, a family of four in a northern climate would need between 64 and 68 square feet (5.9 and 6.3 square meters) of collector area and a 96- to 102-gallon (363- to 386-liter) storage tank. (This assumes 20 square feet of collector area for the first person, 20 for the second person, 12 to 14 for the third person, and 12 to 14 for the fourth person. This equals 64 to 68 square feet, multiplied by 1.5 gallons of storage capacity, which equals 96 to 102 gallons of storage.) Because you might not be able to find a 96-gallon tank, you may want to get a 120-gallon tank to be sure to meet your hot water needs.

Benefits of Solar Water Heaters
There are many benefits to owning a solar water heater, and number one is economics. Solar water heater economics compare quite favorably with those of electric water heaters, while the economics aren't quite so attractive when compared with those of gas water heaters. Heating water with the sun also means long-term benefits, such as being cushioned from future fuel shortages and price increases, and environmental benefits.

Economic Benefits
Many home builders choose electric water heaters because they are easy to install and relatively inexpensive to purchase. However, research shows that an average household with an electric water heater spends about 25% of its home energy costs on heating water.

It makes economic sense to think beyond the initial purchase price and consider lifetime energy costs, or how much you will spend on energy to use the appliance over its lifetime. It found that solar water heaters offered the largest potential savings compared to electric heating, with solar water-heater owners saving as much as 50% to 85% annually on their utility bills over the cost of electric water heating.

However, at the current low prices of natural gas, solar water heaters cannot compete with natural gas water heaters in most parts of the country except in new home construction. Although you will still save energy costs with a solar water heater because you won't be buying natural gas, it won't be economical.

Paybacks vary widely, but you can expect a simple payback of 3 to 8 years on a well-designed and properly installed solar water heater. (Simple payback is the length of time required to recover your investment through reduced or avoided energy costs.) You can expect shorter paybacks in areas with higher energy costs. After the payback period, you accrue the savings over the life of the system, which ranges from 15 to 40 years, depending on the system and how well it is maintained.

You can determine the simple payback of a solar water heater by first determining the net cost of the system. Net costs include the total installed cost less any tax incentives or utility rebates. (See the box for more information.) After you calculate the net cost of the system, calculate the annual fuel savings and divide the net investment by this number to determine the simple payback.

Tax Incentives and Rebates
In India some States offer subsidies on domestic as well as commercial solar water heating systems installations. Government of India offers 100% depreciation claim in the first year itself on installation of commercial solar water heating systems.

Long-Term Benefits
Solar water heaters offer long-term benefits that go beyond simple economics. In addition to having free hot water after the system has paid for itself in reduced utility bills, you and your family will be cushioned from future fuel shortages and price increases. You will also be doing your part to reduce this country's dependence on foreign oil. The National Remodelers Association reports that adding a solar water heater to an existing home raises the resale value of the home by the entire cost of the system. You may be able to recoup your entire investment when you sell your home.

Environmental Benefits
Solar water heaters do not pollute. By investing in one, you will be avoiding carbon dioxide, nitrogen oxides, sulfur dioxide, and the other air pollution and wastes created when your utility generates power or you burn fuel to heat your household water. When a solar water heater replaces an electric water heater, the electricity displaced over 20 years represents more than 50 tons of avoided carbon dioxide emissions alone. Carbon dioxide traps heat in the upper atmosphere, thus contributing to the "greenhouse effect."

Be a Smart Consumer
Take the same care in choosing a solar water heater that you would in the purchase of any major appliance.

A Bright Future
A solar water heater is a long-term investment that will save you money and energy for many years. Like other renewable energy systems, solar water heaters minimize the environmental effects of enjoying a comfortable, modern lifestyle. In addition, they provide insurance against energy price increases, help reduce our dependence on foreign oil, and are investments in everyone's future.

You might also consider other solar energy systems for your home. Systems similar to the solar water heater are used for space heating and swimming pool heating. In fact, pool heating is a major market for solar energy systems.

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SURVEY ON SOLAR WATER HEATER USERS
A survey conducted in a typical city of India amongst users of solar water heating system would give a breakup somewhat along the following lines… 100% of the users are in the middle higher to higher income group 70% and above prefer systems with electrical backup while less than 30% opted for stand alone solar water heaters. More than 80% of the users bought the systems directly from the manufacturer without any third party financing or loan. More than 90% of the users found a solar water heating system to be satisfactory, especially in saving fuel costs. More than 90% of users would have liked "subsidy" to be available on solar water heating systems. In fact most have purchased the system under subsidy scheme.

Are you a user of a solar water heating system? Regardless..do you have your views to share with the world? Please write in and we will display it on these pages.

RURAL ENERGY IN INDIA – Biomass Gasifiers
Being an agrarian country there is easy availability of agricultural based mass which can be used to generate energy Burning this biomass is the easiest and oldest method of generating energy and also the least efficient. Over 70% of the population of India is in villages but it is these villages which receive neither electricity nor a steady supply of water-crucial to survival and economic and social development and growth. No educational facilities for higher studies exist in these villages and neither can we find sophisticated hospitals or industries. All because of lack of electricity and water. Biomasss exists in these villages and needs to be tapped intelligently to provide not only electricity but also water to irrigate and cultivate fields to further increase production of biomass (either as a main product or as a by-product), ensuring steady generation of electricity. An added bonus is the availability of waste biomass from the biomass gasifier plant to be used as fertilizer. Most common source of biomass is wood waste and agricultural wastes. In India development of biomass gasification has received serious attention with establishment of biomass research centers and gasifier action research centers at various locations spread all over the country. These institutions have played a key role in upgradation and adaption of suitable technologies, testing, monitoring and development of biomass gasification systems. Studies reveal that the low grade of land suitable only for scrub vegetation can be turned to advantage and form an excellent source of biomass – fast growing trees and shrubs. In India more than 2000 gasifiers are estimated to have been established with a capacity in excess of 22 MW and a number of villages have been electrified with biomass gasifier based generators. MNES has actively promoted research and development programmes for efficient utilization of biomass and agrowastes and further efforts are on. Biomass gasification offers immense scope and potential for : • Water pumping • Electricity generation : 3 to 1 MW power plants • Heat generation : for cooking gas – smokeless environment • Rural electrification means better healthcare, better education and improved quality of life.

IREDA – the prime lending institution for renewable energy projects is actively assisting installation of biomass gasifiers.
note: material appearing above is excerpted from various sources without our liability or responsibility for veracity

Interesting Links
Do YOU know an interesting site on the topic of renewables readers would like to visit? Please let us know: we will feature its link here.

Energy Efficiency and Conservation http://www.ase.org/ceeci Council of Energy Efficiency Companies of India http://www.weea.org World Energy Efficiency Association..Energy efficiency news, international directory, energy efficiency on the Web, reports and publications, regional information....more http://www.energy-efficiency.gov.uk Energy Efficiency best practice programme http://ireda.nic.in Indian Renewable Energy Development Agency....premier and only lending/financing institution of India for renewable energy systems. http://www.arrpeec.ait.ac.th Asian Regional Research Programme in Energy Environment and Climate http://www.winrockindia.org Winrock International India. ...energy and environment, natural resources management, agriculture and enterprise development...outreach http://www.energyefficiency-cii.com ADB Energy Efficiency Support Project in India...funded by governments of Netherlands and India, sponsored by ADB and ICICI. http://www.ebrd.com/english/index.htm The European Bank for Reconstruction and Development (EBRD) http://www.letconserve.com/main.htm Forum for Energy Conservation http://www.eren.doe.gov/ee.htm Energy Efficiency and Renewable Energy Network http://www.worldenergy.org World Energy Council ..a global multi energy organization with over 90 member countries including largest energy producing and consuming countries. WEC covers all types of energy and is UN-accredited and non-aligned, headquartered in London. http://www.bir.org Bureau of International Recycling...the international trade association of the recycling industries based in Brussels, Belgium. http://www.nwalliance.org The Northwest Energy Efficiency Alliance.. information about energy efficiency projects, project marketing, updates on energy efficient products, and training resources. http://www.vidyutsanchay.com EarnEnergy.com...a watt saved is a watt earned.

http://www.ecee.org Export Council for Energy Efficiency.... mission is to promote global use of energy efficiency products and services.. http://www.eeba.org Energy and Environmental Building Association. ... an international association to promote awareness, education and development of energy efficient, environmentally responsible buildings and communities. http://www.aeecenter.org The Association of Energy Engineers...a source of information on the dynamic field of energy efficiency, utility deregulation, facility management, plant engineering and environmental compliance. http://www.ecn.nl Netherlands Energy Research Foundation..ECN contributes to energy efficiency, implementation of renewable energy and reduction of environmentally harmful emissions from fossil fuels. http://www.aceee.org The American Council for an Energy Efficient Economy ...exploring the frontiers of energy policy and energy efficiency. http://www.eia.doe.gov Centre for Energy Efficiency (CENEf) .. created to promote energy efficiency in Russia http://www.vidyutsanchay.com Information on industrial energy conservation...list of subsidies...manufacturers and suppliers of energy efficient equipment...financing schemes for energy conservation projects., http://www.ecee.org Export Council for Energy Efficiency...mission to promote global use of energy efficiency http://www.aeecenter.org Association of Energy Engineers..source of information on the dynamic field of energy efficiency.. http://www.naesco.org NAESCO website http://www.letconserve.com/main.html Forum for Energy Conservation

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In order to directly compare world energy resources and consumption of energy, this article uses SI units and prefixes and measures energy rate (or power) in watts (W) and amounts of energy in joules (J). One watt is one joule per second. In 2005, total worldwide energy consumption was 500 EJ (= 5 x 1020 J) with 86.5% derived from the combustion of fossil fuels, although there is at least 10% uncertainty in that figure.[1] This is equivalent to an average energy consumption rate of 15 TW (= 1.5 x 1013 W). Not all of the

world's economies track their energy consumption with the same rigor, and the exact energy content of a barrel of oil or a ton of coal will vary with quality. Most of the world's energy resources are from the sun's rays hitting earth - some of that energy has been preserved as fossil energy, some is directly or indirectly usable e.g. via wind, hydro or wave power. The term solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just visible light. It is measured by satellite to be roughly 1366 watts per square meter, though it fluctuates by about 6.9% during a year - from 1412 W/m2 in early January to 1321 W/m2 in early July, due to the earth's varying distance from the sun, and by a few parts per thousand from day to day. For the whole Earth, with a cross section of 127,400,000 km², the total energy rate is 1.740×1017 W, plus or minus 3.5%. This 174 PW is the total rate of solar energy received by the planet; about half, 89 PW, reaches the earth's surface. The estimates of remaining worldwide energy resources vary, with the remaining fossil fuels totaling an estimated 0.4 YJ (1 YJ = 1024J) and the available nuclear fuel such as uranium exceeding 2.5 YJ. Fossil fuels range from 0.6-3 YJ if estimates of reserves of methane clathrates are accurate and become technically extractable. Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total usage), or 3.8 YJ/yr, dwarfing all non-renewable resources.

 

Rate of world energy usage in terawatts (TW), 1965-2005[1]

World_en nergy_usage e_width_cha art.svg (SVG file, nomin G nally 1,040 × 850 pixels, file size: 29 9 KB)

Energy i intensity of different ec conomies Th graph sho the ratio between en he ows nergy usage a and GNP for selected cou untries. GNP is based on 2004 purch P n hasing power parity and 2000 dollars r s adjusted for inflation [4] n.

Energy consumption per capita versus the GNP per capita The graph plots the per capita energy versus the per capita income for all countries with more than 20 million inhabitants, the data more than 90% of the world's population. The image shows the broad relation between wealth and energy consumption.[5]

GDP and energy consumption in Japan from 1958 - 2000 The data shows the correlation between GDP and energy use; however, it also shows that this link can be broken. After the oil shocks of 1973 and 1979 the energy use stagnated while Japan's GDP continued to grow, after 1985, under the influence of the then much cheaper oil, energy use resumed its historical relation to GDP.[6]

Worldwide energy supply in TW[4]

Renewable energy sources worldwide at the end of 2006 Source: REN21[9]  Renewable energy sources worldwide at the end of 2006 Source: REN21[9] 

[edit] Consumption

[edit] Fossil fuels Main article: Fossil fuel The twentieth century saw a rapid twentyfold increase in the use of fossil fuels. Between 1980 and 2004, the worldwide annual growth rate was 2%. [1] According to the US Energy Information Administration's 2006 estimate, the estimated 15TW total consumption of 2004 was divided as follows, with fossil fuels supplying 86% of the world's energy:

Fuel type

Average Energy/year power in in EJ [1] TW

Oil

5.6

180

Gas

3.5

110

Coal

3.8

120

Hydroelectric

0.9

30

Nuclear

0.9

30

Geothermal, wind, 0.13 solar, wood

4

Total

15

471

Coal fueled the industrial revolution in the 18th and 19th century. With the advent of the automobile, airplanes and the spreading use of electricity, oil became the dominant fuel during the twentieth century. The growth of oil as the largest fossil fuel was further enabled by steadily dropping prices from 1920 until 1973. After the oil shocks of 1973 and 1979, during which the price of oil increased from 5 to 45 US dollars per barrel, there was a shift away from oil.[12] Coal and nuclear became the fuels of choice for electricity generation and conservation measures increased energy efficiency. In the US the average car more than doubled the number of miles per gallon. Japan, which bore the brunt of the oil shocks, made spectacular improvements and now has the highest energy efficiency in the world.[5] Over the last forty years, the use of fossil fuels has continued to grow and their share of the energy supply has increased. In the last three

years, coal, which is one of the dirtiest sources of energy,[13] has become the fastest growing fossil fuel.[14]. [edit] Nuclear power In 2005 nuclear power accounted for 6.3% of world's total primary energy supply.[15] The nuclear power production in 2006 accounted 2,658 TWh (23.3 EJ), which was 16% of world's total electricity production.[16][17] In November 2007, there were 439 operational nuclear reactors worldwide, with total capacity of 372,002 MWe. A further 33 reactors were under construction, 94 reactors were planned and 222 reactors were proposed.[16] [edit] Renewable energy Main article: Renewable energy In 2004, renewable energy supplied around 7% of the world's energy consumption.[18] The renewables sector has been growing significantly since the last years of the 20th century, and in 2005 the total new investment was estimated to have been 38 billion US dollars. Germany and China lead with investments of about 7 billion US dollars each, followed by the United States, Spain, Japan, and India. This resulted in an additional 35 GW of capacity during the year.[3]
[edit] Hydropower

Main article: hydropower Worldwide hydroelectricity consumption reached 816 GW in 2005, consisting of 750 GW of large plants, and 66 GW of small hydro installations. Large hydro capacity totaling 10.9 GW was added by China, Brazil and India during the year, but there was a much faster growth (8%) in small hydro, with 5 GW added, mostly in China where some 58% of the world's small hydro plants are now located.[3] In the Western world, although Canada is the largest producer of hydroelectricity in the world, the construction of large hydro plants has stagnated due to environmental concerns.[19] The trend in both Canada and the United States has been to micro hydro because it has negligible environmental impacts and opens up many more locations for power generation. In British Columbia alone the estimates are that micro hydro will be able to more than double electricity production in the province.
[edit] Biomass and biofuels

Main articles: biomass and biofuel Until the end of the nineteenth century biomass was the predominant fuel, today it has only a small share of the overall energy supply. Electricity produced from biomass sources was estimated at 44 GW for 2005. Biomass electricity generation increased by over 100% in Germany, Hungary, the Netherlands, Poland and Spain. A further 220 GW was used for heating

(in 2004), bringing the total energy consumed from biomass to around 264 GW. The use of biomass fires for cooking is excluded.[3] World production of bioethanol increased by 8% in 2005 to reach 33 billion litres (8.72 billion US gallons), with most of the increase in the United States, bringing it level to the levels of consumption in Brazil.[3] Biodiesel increased by 85% to 3.9 billion litres (1.03 billion US gallons), making it the fastest growing renewable energy source in 2005. Over 50% is produced in Germany.[3]
[edit] Wind power

Main article: Wind power According to the Global Wind Energy Council, the installed capacity of wind power increased by 27% from the end of 2006 to the end of 2007 to total 94.1 GW, with over half the increase in the United States, Spain and China.[20] Doubling of capacity took about three years. The total installed capacity is approximately three times that of the actual average power produced as the nominal capacity represents peak output; actual capacity is generally from 25-40% of the nominal capacity.[21]
[edit] Solar power

Main article: Solar energy The available solar energy resources are 3.8 YJ/yr (120,000 TW). Less than 0.02% of available resources are sufficient to entirely replace fossil fuels and nuclear power as an energy source. Assuming that our rate of usage in 2005 remains constant, we will run out of conventional oil in 40 years (2045), coal in 154 yrs (2159). In practice neither will actually run out, as natural constraints will force production to decline as the remaining reserves dwindle.[22][23][24] In 2007 grid-connected photovoltaic electricity was the fastest growing energy source, with installations of all photovoltaics increasing by 83% in 2007 to bring the total installed capacity to 8.7 GW. Nearly half of the increase was in Germany, now the world's largest consumer of photovoltaic electricity (followed by Japan). Solar cell production increased by 50% in 2007, to 3,800 megawatts, and has been doubling every two years.[25] The world's most powerful photovoltaic solar power plant is the 20 megawatt Beneixama photovoltaic power plant in Spain, although a 116 megawatt plant is under construction in southern Portugal, one of the sunniest places in Europe.[26] The largest photovoltaic installation in North America is the 18 megawatt Nellis Solar Power Plant. Since 1991 the largest solar power plant has been the 354 megawatt Solar Energy Generating Systems, in the Mohave Desert in California, using parabolic trough collectors. Stirling Energy Systems is currently building a 500MW solar power plant using solar concentrators and Stirling engines with a 750MW plant also planned.

The consumption of solar hot water and solar space heating was estimated at 88 GWt (gigawatts of thermal power) in 2004. The heating of water for unglazed swimming pools is excluded.[3]
[edit] Geothermal

Main article: Geothermal power Geothermal energy is used commercially in over 70 countries.[27] By the end of 2005 worldwide use for electricity had reached 9.3 GW, with an additional 28 GW used directly for heating.[3] If heat recovered by ground source heat pumps is included, the non-electric use of geothermal energy is estimated at more than 100 GW.[27]

[edit] By country
See also: Energy by country and List of countries by energy consumption per capita Energy consumption is loosely correlated with gross national product, but there is a large difference even between the most highly developed countries, such as Japan and Germany with 6 kW per person and United States with 11.4 kW per person. In developing countries such as India the per person energy use is closer to 0.7 kW. Bangladesh has the lowest consumption with 0.2 kW per person. The US consumes 25% of the world's energy (with a share of global productivity at 22% and a share of the world population at 5%). The most significant growth of energy consumption is currently taking place in China, which has been growing at 5.5% per year over the last 25 years. Its population of 1.3 billion people is consuming energy at a rate of 1.6 kW per person. Over the past four years, electricity consumption per capita in the U.S. has decreased about 1% per year between 2004 and 2008. Power consumption is projected to hit 4,333,631 million kilowatt hours by 2013, an annual growth rate of 1.93% for the next five years. Consumption increased from 3,715,949 in 2004 to an expected 3,937,879 million kilowatt hours per year in 2008, an increase of about 0.36% per year. U.S. population has been increasing about 1.3% per year, a total increase of about 6.7% over five years.[28] The decrease has been mostly due to efficiency increases. Compact fluorescent bulbs, for example use about one third as much electricity as incandescents. LED bulbs, however, use about one tenth as much, and over their 50,000 to 100,000 hour lifetime are cheaper than compact fluorescents. One metric of efficiency is energy intensity. This is a measure of the amount of energy it takes a country to produce a dollar of gross domestic product.

[edit] By sector
Industrial users (agriculture, mining, manufacturing, and construction) consume about 37% of the total 15 TW. Personal and commercial transportation consumes 20%; residential heating, lighting, and appliances use 11%; and commercial uses (lighting, heating and cooling of commercial buildings, and provision of water and sewer services) amount to 5% of the total. [29]

The other 27% of the world's energy is lost in energy transmission and generation. In 2005, global electricity consumption averaged 2 TW. The energy rate used to generate 2 TW of electricity is approximately 5 TW, as the efficiency of a typical existing power plant is around 38%.[30] The new generation of gas-fired plants reaches a substantially higher efficiency of 55%. Coal is the most common fuel for the world's electricity plants.[31]

[edit] Resources
[edit] Fossil fuel
Main article: Fossil fuel Remaining reserves of conventional fossil fuels are estimated as:[8]

Fuel

Energy reserves in ZJ

Coal

290.0

Oil

18.4

Gas

15.7

Significant uncertainty exists for these numbers, and they may be too optimistic. The estimation of the remaining fossil fuels on the planet depends on a detailed understanding of the Earth crust. This understanding is still less than perfect. While modern drilling technology makes it possible to drill wells in up to 3 km of water to verify the exact composition of the geology, one half of the ocean is deeper than 3 km, leaving about a third of the planet beyond the reach of detailed analysis. It is, however, known that deep ocean rock is principally volcanic, and volcanic rock is nowhere associated with petroleum. The Energy Watch Group reports show that we already cannot supply the demand for oil,[32] and that uranium resources will be exhausted within 70 years.[33] [edit] Coal Main article: World coal reserves Coal is the most abundant fossil fuel. According to the International Energy Agency the proven reserves of coal are around 909 billion tonnes, which could sustain at the current production rate for 155 years.[34] This was the fuel that launched the industrial revolution and has continued to

grow in use; China, which already has many of the world's most polluted cities,[35] was in 2007 building about two coal fired power plants every week.[36][37] Coal is the fastest growing fossil fuel and its large reserves would make it a popular candidate to meet the energy demand of the global community, short of global warming concerns and other pollutants.[38] With the FischerTropsch process it is possible to make liquid fuels such as diesel and jet fuel from coal. The Stop Coal campaign calls for a moratorium on the construction of any new coal plants and on the phase out of all existing plants, citing concern for global warming.[39] In the United States, 49% of electricity generation comes from burning coal.[40] [edit] Oil See also: Oil reserves and Peak oil It is estimated that there may be 57 ZJ of oil reserves on Earth (although estimates vary from a low of 8 ZJ,[1] consisting of currently proven and recoverable reserves, to a maximum of 110 ZJ[citation needed]) consisting of available, but not necessarily recoverable reserves, and including optimistic estimates for unconventional sources such as tar sands and oil shale. Current consensus among the 18 recognized estimates of supply profiles is that the peak of extraction will occur in 2020 at the rate of 93-million barrels per day (mbd). Current oil consumption is at the rate of 0.18 ZJ per year (31.1 billion barrels) or 85-mbd. There is growing consensus that peak oil production may be reached in the near future, resulting in severe oil price increases.[41] A 2005 French Economics, Industry and Finance Ministry report suggested a worst-case scenario that could occur as early as 2013.[42] There are also theories that peak of the global oil production may occur in as little as 2-3 years. The ASPO predicts peak year to be in 2010. Some other theories present the view that it has already taken place in 2005. World oil production decreased from a peak of 84.58 mbd in 2005 to 84.54 mbd in 2006 and to 84.40 in 2007.[43] According to peak oil theory, increasing production will lead to a more rapid collapse of production in the future, while decreasing production will lead to a slower decrease, as the bell-shaped curve will be spread out over more years. In a stated goal of increasing oil prices to $75/barrel, which had fallen from a high of $147 to a low of $40, OPEC announced decreasing production by 2.2 mbd beginning January 1, 2009.[44] [edit] Sustainability Political considerations over the security of supplies, environmental concerns related to global warming and sustainability will move the world's energy consumption away from fossil fuels. The concept of peak oil shows that we have used about half of the available petroleum resources, and predicts a decrease of production. A government led move away from fossil fuels would most likely create economic pressure through carbon emissions trading and green taxation. Some countries are taking action as a result of the Kyoto Protocol, and further steps in this direction are proposed. For example, the European Commission has proposed that the energy policy of the European Union should set a

binding target of increasing the level of renewable energy in the EU's overall mix from less than 7% today to 20% by 2020.[45]

[edit] Nuclear power
See also: Nuclear power and Nuclear energy policy [edit] Nuclear fission See also: Nuclear fuel The International Atomic Energy Agency estimates the remaining uranium resources to be equal to 2500 ZJ.[46] This assumes the use of Breeder reactors which are able to create more fissile material than they consume. IPCC estimated currently proved economically recoverable uranium deposits for once-through fuel cycles reactors to be only 2 ZJ. The ultimately recoverable uranium is estimated to be 17 ZJ for once-through reactors and 1000 ZJ with reprocessing and fast breeder reactors. [47] Resources and technology do not constrain the capacity of nuclear power to contribute to meeting the energy demand for the 21st century. However, political and environmental concerns about nuclear safety and radioactive waste started to limit the growth of this energy supply at the end of last century, particularly due to a number of nuclear accidents. Concerns about nuclear proliferation (especially with Plutonium produced by breeder reactors) mean that the development of nuclear power by countries such as Iran and Syria is being actively discouraged by the international community.[48] [edit] Nuclear fusion Fusion power is the process driving our sun and other stars. It generates large quantities of heat by fusing the nuclei of hydrogen or helium isotopes, which may be derived from seawater. The heat can theoretically be harnessed to generate electricity. The temperatures and pressures needed to sustain fusion make it a very difficult process to control. The tantalizing potential of fusion is its theoretical ability to supply vast quantities of energy, with relatively little pollution.[49] Both the United States and the European Union are supporting a high level of research (such as investing in the ITER facility), along with other countries. According to one report, inadequate research has stalled progress in fusion research for the past 20 years, and under these conditions is 50 years away from commercial availability.[50]

[edit] Renewable resources
Main article: Renewable resource Renewable resources are available each year, unlike non-renewable resources which are eventually depleted. A simple comparison is a coal mine and a forest. While the forest could be depleted, if it is managed properly it represents a continuous supply of energy, vs the coal mine which once it has been exhausted is gone. Most of earth's available energy resources are

renewable resources. Renewable resources account for more than 93 percent of total U.S. energy reserves. Annual renewable resources were multiplied times thirty years for comparison with non-renewable resources. In other words, if all non-renewable resources were uniformly exhausted in 30 years, they would only account for 7 percent of available resources each year, if all available renewable resources were developed.[51] [edit] Solar energy Main article: Solar energy Renewable energy sources are even larger than the traditional fossil fuels and in theory can easily supply the world's energy needs. 89 PW[52] of solar power falls on the planet's surface. While it is not possible to capture all, or even most, of this energy, capturing less than 0.02% would be enough to meet the current energy needs. Barriers to further solar generation include the high price of making solar cells and reliance on weather patterns to generate electricity. Also, solar generation does not produce electricity at night, which is a particular problem in high northern and southern latitude countries; energy demand is highest in winter, while availability of solar energy is lowest. Globally, solar generation is the fastest growing source of energy, seeing an annual average growth of 35% over the past few years. Japan, Europe, China, U.S. and India are the major growing investors in solar energy. Advances in technology and economies of scale, along with demand for solutions to global warming, have led photovoltaics to become the most likely candidate to replace nuclear and fossil fuels.[53] [edit] Wind power Main article: Wind power The available wind energy estimates range from 300 TW to 870 TW.[52][54] Using the lower estimate, just 5% of the available wind energy would supply the current worldwide energy needs. Most of this wind energy is available over the open ocean. The oceans cover 71% of the planet and wind tends to blow stronger over open water because there are fewer obstructions. [edit] Wave and tidal power Main articles: Wave power and Tidal power At the end of 2005, 0.3 GW of electricity was produced by tidal power. [3] Due to the tidal forces created by the Moon (68%) and the Sun (32%), and the Earth's relative rotation with respect to Moon and Sun, there are fluctuating tides. These tidal fluctuations result in dissipation at an average rate of about 3.7 TW. [55] As a result, the rotational speed of the Earth decreases, and the distance of the Moon to the Earth increases, on geological time scales. In several billion years, the Earth will rotate at the same speed as the Moon is revolving around it. So, several TW of tidal energy can be produced without having a significant effect on celestial mechanics[citation needed] .

Another physical limitation is the energy available in the tidal fluctuations of the oceans, which is about 0.6 EJ (exajoule). [56] Note this is only a tiny fraction of the total rotational energy of the Earth. Without forcing, this energy would be dissipated (at a dissipation rate of 3.7 TW) in about four semi-diurnal tide periods. So, dissipation plays a significant role in the tidal dynamics of the oceans. Therefore, this limits the available tidal energy to around 0.8 TW (20% of the dissipation rate) in order not to disturb the tidal dynamics too much.[citation needed] Waves are derived from wind, which is in turn derived from solar energy, and at each conversion there is a drop of about two orders of magnitude in available energy. The total power of waves that wash against our shores add up to 3 TW. [57] [edit] Geothermal Main article: Geothermal power Estimates of exploitable worldwide geothermal energy resources vary considerably. According to a 1999 study, it was thought that this might amount to between 65 and 138 GW of electrical generation capacity 'using enhanced technology'.[58] A 2006 report by MIT that took into account the use of Enhanced Geothermal Systems (EGS) concluded that it would be affordable to generate 100 GWe (gigawatts of electricity) or more by 2050, just in the United States, for a maximum investment of 1 billion US dollars in research and development over 15 years.[27] The MIT report calculated the world's total EGS resources to be over 13 YJ, of which over 200 ZJ would be extractable, with the potential to increase this to over 2 YJ with technology improvements - sufficient to provide all the world's energy needs for several millennia.[27] [edit] Biomass Main articles: biomass and biofuel Production of biomass and biofuels are growing industries as interest in sustainable fuel sources is growing. Utilizing waste products avoids a food vs fuel trade-off, and burning methane gas reduces greenhouse gas emissions, because even though it releases carbon dioxide, carbon dioxide is 23 times less of a greenhouse gas than is methane. Biofuels represent a sustainable partial replacement for fossil fuels, but their net impact on greenhouse gas emissions depends on the agricultural practices used to grow the plants used as feedstock to create the fuels. While it is widely believed that biofuels can be carbon-neutral, there is evidence that biofuels produced by current farming methods are substantial net carbon emitters.[59][60][61] Geothermal and biomass are the only two renewable energy sources which require careful management to avoid local depletion.[62] [edit] Hydropower Main article: hydropower

In 2005, hydroelectric power supplied 16.4% of world electricity.[63] Large dams are still being designed. Nevertheless, hydroelectric power is probably not a major option for the future of energy production in the developed nations because most major sites within these nations are either already being exploited or are unavailable for other reasons, such as environmental considerations.

[edit] Alternative energy paths
Denmark and Germany have started to make investments in solar energy, despite their unfavorable geographic locations. Germany is now the largest consumer of photovoltaic cells in the world. Denmark and Germany have installed 3 GW and 17 GW of wind power respectively. In 2005, wind generated 18.5% of all the electricity in Denmark.[64] Brazil invests in ethanol production from sugar cane which is now a significant part of the transportation fuel in that country. Starting in 1965, France made large investments in nuclear power and to this date three quarters of its electricity comes from nuclear reactors.[65] Switzerland is planning to cut its energy consumption by more than half to become a 2000-watt society by 2050 and the United Kingdom is working towards a zero energy building standard for all new housing by 2016. In 2005, the Swedish government announced the oil phase-out in Sweden with the intention to become the first country to break its dependence on fossil fuel by 2020.
Coal, oil and gas are called "fossil fuels" because they have been formed from the organic remains of prehistoric plants and animals. Find out more about how they formed at www.energyquest.ca.gov/story/chapter08.html

At the time this page was written, fossil fuels provided around 66% of the world's electrical power, and 95% of the world's total energy demands (including heating, transport, electricity generation and other uses).

How it works:
Coal is crushed to a fine dust and burnt. Oil and gas can be burnt directly.

The main bit to remember:

Video clip: Fossil fuel power station - how it works

The steam that has passed through the power station's turbines has to be cooled, to condense it back into water before it can be pumped round again. This is what happens in the huge "cooling towers" seen at power stations.
Find out about Drax Coal-fired power station in

Selby, UK

 

Some power stations are built on the coast, so they can use sea water to cool the steam instead. However, this warms the sea and can affect the environment, although the fish seem to like it.

 

More:
Coal provides around 28% of our energy, and oil provides 40%. Mind you, this figure is bound to have changed since this page was written, so check the figures if you want to quote them.

Burning coal produces sulphur dioxide, an acidic gas that contributes to the formation of acid rain. This can be largely avoided using "flue gas desulphurisation" to clean up the gases before they are released into the atmosphere. This method uses limestone, and produces gypsum for the building industry as a by-product. However, it uses a lot of limestone.
More details on 'clean coal technology' from BBC News web site... Crude oil (called "petroleum") is easier to get out of the ground than coal, as it can flow along pipes. This also makes it cheaper to transport.

I ought to point out that some scientists are claiming that oil is not a 'fossil' fuel - that it is not the remains of prehistoric organisms after all. They claim it was made by some other, non-biological process. Currently this is not accepted by the majority of scientists, but you can find out more

Video clip: What is crude oil?

 

about the idea at space.com

Natural gas

provides around 20% of the world's consumption of energy, and as well as being burnt in power stations, is used by many people to heat their homes. It is easy to transport along pipes, and gas power stations produce comparatively little pollution.

Other fossil fuels are being investigated, such as bituminous sands and oil shale. The difficulty is that they need expensive processing before we can use them; however Canada has large reserves of 'tar sands' , which makes it economic for them to produce a great deal of energy this way.

As far as we know, there is still a lot of oil in the ground. But although oil wells are easy to tap when they're almost full, it's much more difficult to get the oil up later on when there's less oil down there. That's one reason why we're increasingly looking at these other fossil fuels.
Find out more at www.eia.doe.gov/emeu/cabs/canada.html

   

Advantages

• • • •

Very large amounts of electricity can be generated in one place using coal, fairly cheaply. Transporting oil and gas to the power stations is easy.
 

Gas-fired power stations are very efficient. A fossil-fuelled power station can be built almost anywhere, so long as you can get large quantities of fuel to it. Didcot power station, in Oxfordshire, has a dedicated rail link to supply the coal.

 

Disadvantages

•

Basically, the main drawback of fossil fuels is pollution. Burning any fossil fuel produces carbon dioxide, which contributes to the "greenhouse effect", warming the Earth.

•

Burning coal produces more carbon dioxide than burning oil or gas. It also produces sulphur dioxide, a gas that contributes to acid rain. We can reduce this before releasing the waste gases into the atmosphere.
More details on 'clean coal technology' from BBC News web site...

• •

Mining coal can be difficult and dangerous. Strip mining destroys large areas of the landscape. Coal-fired power stations need huge amounts of fuel, which means train-loads of coal almost constantly. In order to cope with changing demands for power, the station needs reserves. This means covering a large area of countryside next to the power station with piles of coal.

 

Is it renewable?

Fossil fuels are not a renewable energy resource. Once we've burned them all, there isn't any more, and our consumption of fossil fuels has nearly doubled every 20 years since 1900. This is a particular problem for oil, because we also use it to make plastics and many other products. Ok, you could argue that fossil fuels are renewable because more coal seams and oil fields will be formed if we wait long enough. However that means waiting for many millions of years. That's a long time - we'd have to wait around for longer than the time that humans have existed so far! As far as we today are concerned, we're using it up very fast and it hardly gets replaced at all - so by any sensible human definition fossil fuels are not renewable.  

Nuclear Power energy from splitting Uranium atoms  
Introduction  

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Nuclear power is generated using Uranium, which is a metal mined in various parts of the world. The first large-scale nuclear power station opened at Calder Hall in Cumbria, England, in 1956. Some military ships and submarines have nuclear power plants for engines. Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without the pollution that you'd get from burning fossil fuels.

 
How it works:  

The main bit to remember:

Nuclear power stations work in pretty much the same way as fossil fuel-burning stations, except that a "chain reaction" inside a nuclear reactor makes the heat instead. The reactor uses Uranium rods as fuel, and the heat is generated by nuclear fission: neutrons smash into the nucleus of the uranium atoms, which split roughly in half and release energy in the form of heat. Carbon dioxide gas or water is pumped through the reactor to take the heat away, this then heats water to make steam. The steam drives turbines which drive generators.

Video clip: Nuclear reactor

 

Modern nuclear power stations use the same type of turbines and generators as conventional power stations. In Britain, nuclear power stations are often built on the coast, and use sea water for cooling the steam ready to be pumped round again. This means that they don't have the huge "cooling towers" seen at other power stations.

The reactor is controlled with "control rods", made of boron, which absorb neutrons. When the rods are lowered into the reactor, they absorb more neutrons and the fission process slows down. To generate more power, the rods are raised and more neutrons can crash into uranium atoms.

 
More:  

Natural uranium is only 0.7% "uranium-235", which is the type of uranium that undergoes fission in this type of reactor. The rest is U-238, which just sits there getting in the way. Modern reactors use "enriched" uranium fuel, which has a higher proportion of U-235. The fuel arrives encased in metal tubes, which are lowered into the reactor whilst it's running, using a special crane sealed onto the top of the reactor.

 

With an AGR or Magnox station, carbon dioxide gas is blown through the reactor to carry the heat away. Carbon dioxide is chosen because it is a very good coolant, able to carry a great deal of heat energy. It also helps to reduce any fire risk in the reactor (it's around 600 degrees Celsius in there) and it doesn't turn into anything nasty (well, nothing long-lived and nasty) when it's bombarded with neutrons. You have to be very careful about the materials you use to build reactors - some materials will turn into horrible things in that environment. If a piece of metal in the reactor pressure vessel turns brittle and snaps, you're probably in trouble - once the reactor has been built and started you can't go in there to fix anything.. Uranium itself isn't particularly radioactive, so when the fuel rods arrive at the power station they can be handled using thin plastic gloves. A rod can last for several years before it needs replacing. It's when the "spent" fuel rods are taken out of the reactor that you need the full remote-control robot arms and Homer Simpson equipment.
Should I worry about nuclear power?

 

Nuclear power stations are not atomic bombs waiting to go off, and are not prone to "meltdowns". There is a lot of U-238 in there slowing things down - you need a high concentration of U-235 to make a bomb. If the reactor gets too hot, the control rods are lowered in and it cools down. If that doesn't work, there are sets of emergency control rods that automatically drop in and shut the reactor down completely. With reactors in the UK, the computers will shut the reactor down automatically if things get out of hand

(unless engineers intervene within a set time). At Chernobyl, in Ukraine, they did not have such a sophisticated system, indeed they over-rode the automatic systems they did have. When they got it wrong, the reactor overheated, melted and the excessive pressure blew out the containment system before they could stop it. Then, with the coolant gone, there was a serious fire. Many people lost their lives trying to sort out the mess. A quick web search will tell you more about this, including companies who operate tours of the site.

 
If something does go wrong in a really big way, much of the world could be affected - some radioactive dust (called "fallout") from the Chernobyl accident landed in the UK. That's travelled a long way. With AGR reactors (the most common type in Britain) there are additional safety systems, such as flooding the reactor with nitrogen and/or water to absorb all the neutrons - although the water option means that reactor can never be restarted. So should I worry? I think the answer is "so long as things are being done properly, I don't need to worry too much. The bit that does worry me is the small amount of high-level nuclear waste from power stations. Although there's not much of it, it's very, very dangerous and we have no way to deal with it apart from bury it and wait for a few thousand years...

 

 

There are many different opinions about nuclear power, and it strikes me that most of the people who protest about it don't have any idea what they're talking about. But please make up your own mind, find out as much as you can, and if someone tries to get you to believe their opinion ask yourself "what's in it for them?"

 
Advantages  

• • • • •

Nuclear power costs about the same as coal, so it's not expensive to make. Does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect.
 

Produces huge amounts of energy from small amounts of fuel. Produces small amounts of waste. Nuclear power is reliable.

 
Disadvantages  

•

Although not much waste is produced, it is very, very dangerous. It must be sealed up and buried for many thousands of years to allow the radioactivity to die away. For all that time it must be kept safe from earthquakes, flooding, terrorists and everything else. This is difficult. Nuclear power is reliable, but a lot of money has to be spent on safety - if it does go wrong, a nuclear accident can be a major disaster. People are increasingly concerned about this - in the 1990's nuclear power was the fastestgrowing source of power in much of the world. In 2005 it was the second slowest-growing.

•

Is it renewable?  

Nuclear energy from Uranium is not renewable. Once we've dug up all the Earth's uranium and used it, there isn't any more.  

Actually, it's not that simple - we can use "fast breeder" reactors to convert uranium into other nuclear fuels whilst also getting the energy from it. There are two types of breeder reactors - ones that make weaponsgrade plutonium and ones that are for energy production.

Find out more about breeder reactors...

 

 

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gy from the Sun

Introduction

We've used the Sun for drying clothes and food for thousands of years, but only recently have we been able to use it for generating power. The Sun is 150 million kilometres away, and amazingly powerful. Just the tiny fraction of the Sun's energy that hits the Earth (around a hundredth of a millionth of a percent) is enough to meet all our power needs many times over.
 

In fact, every

minute, enough energy arrives at the Earth to meet our demands for a whole year - if only we could harness it properly. Currently in the UK there are grants available to help you install solar power in your home.

 

How it works:  

There are three main ways that we use the Sun's energy:-

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countries to cook food. This coffee, although it does take a

More:  

Solar cells provide the energy to run satellites that orbit the Earth. These give us satellite TV, telephones, navigation, weather forecasting, the internet and all manner of other facilities. The graphic shows a GPS satellite. A satellite navigation receiver in a car gets signals from a whole host of these and works out it's own position. Find out more about GPS navigation at howstuffworks.com In California, the Solar One power station uses the Sun's heat to make steam, and drive a generator to make electricity. The station looks a little like the Odeillo solar furnace , except that the mirrors are arranged in -circles around the "power tower". As the Sun moves across the sky, the mirrors turn to keep the rays focussed on the tower, where oil is heated to

3,000 degress Celsius, The heat from the oil is used to generate steam, which then drives a turbine, which in turn drives a generator capable of providing 10kW of electrical power. Solar One was very expensive to build, but as fossil fuels run out and become more expensive, solar power stations may become a better option.
Video clip: How PV solar panels are made

 

One idea that is being considered is to build
solar towers.

 

The idea is very simple - you build a big greenhouse, which is warmed by the Sun. In the middle of the greenhouse you put a very tall tower. The hot air from the greenhouse will rise up this tower, fast - and can drive turbines along the way. This could generate significant amounts of power,

Video clip: solar tower 

 

especially in countries where there is a lot of sunshine and a lot of room, such as Australia.

Advantages  

• •

Solar energy is free - it needs no fuel and produces no waste or pollution. In sunny countries, solar power can be used where there is no easy way to get electricity to a remote place. Handy for low-power uses such as solar powered garden lights and battery chargers, or for helping your home energy bills.

•

Disadvantages  

• •

Doesn't work at night. Very expensive to build solar power stations. Solar cells cost a great deal compared to the amount of electricity they'll produce in their lifetime. Can be unreliable unless you're in a very sunny climate. In the United Kingdom, solar power isn't much use for high-power applications, as you need a large area of solar panels to get a decent amount of power. However, technology has now reached the point where it can make a big difference to your home fuel bills..

•

Is it renewable?  

Solar power is renewable. The Sun will keep on shining anyway, so it makes sense to use it.

  

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Introduction

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We've used the wind as an energy source for a long time. The Babylonians and Chinese were using wind power to pump water for irrigating crops 4,000 years ago, and sailing boats were around long before that. Wind power was used in the Middle Ages, in Europe, to grind corn, which is where the term "windmill" comes from.

 

 

 
How it works:    

The Sun heats our atmosphere unevenly, so some patches become warmer than others. These warm patches of air rise, other air blows in to replace them - and we feel a wind blowing. We can use the energy in the wind by building a tall tower, with a large propellor on the top. The wind blows the propellor round, which turns a generator to produce electricity.

 

 

 
We tend to build many of these towers together, to make a "wind farm" and produce more electricity. The more towers, the more wind, and the larger the propellors, the more electricity we can make. It's only worth building wind farms in places that have strong, steady winds, although boats and caravans increasingly have small wind generators to help keep their batteries charged.

Video clip: Building a wind turbine 

Avonmouth docks, near Bristol  

 
More:    

The best places for wind farms are in coastal areas, at the tops of rounded hills, open plains and gaps in mountains - places where the wind is strong and reliable. Some are offshore. To be worthwhile, you need an average wind speed of around 25 km/h. Most wind farms in the UK are in Cornwall or Wales.

 

 

Isolated places such as farms may have their own wind generators. In California, several "wind farms" supply electricity to homes around Los Angeles. The propellors are large, to extract energy from the largest possible volume of air. The blades can be angled to "fine" or "coarse" pitch, to cope with varying wind speeds, and the generator and propellor can turn to face the wind wherever it comes from. Some designs use vertical turbines, which don't need to be turned to face the wind. The towers are tall, to get the propellors as high as possible, up to where the wind is stronger. This means that the land beneath can still be used for farming.
See Also:

News, views and analyses from the world's leading independent wind energy magazine, Windpower Monthly, at www.windpower-monthly.com

The British Wind Energy Association at www.bwea.com

Wind generators for home use: www.windsave.com

 

Advantages  

• • • • •

Wind is free, wind farms need no fuel. Produces no waste or greenhouse gases. The land beneath can usually still be used for farming. Wind farms can be tourist attractions. A good method of supplying energy to remote areas.

 
Disadvantages  

• • • • • •

The wind is not always predictable - some days have no wind.   Suitable areas for wind farms are often near the coast, where land is expensive. Some people feel that covering the landscape with these towers is unsightly. Can kill birds - migrating flocks tend to like strong winds. However, this is rare, and we tend not to build wind farms on migratory routes anyway. Can affect television reception if you live nearby. Can be noisy. Wind generators have a reputation for making a constant, low, "swooshing" noise day and night, which can drive you nuts. Having said that, as aerodynamic designs have improved modern wind farms are much quieter. A lot quieter than, say, a fossil fuel power station; and wind farms tend not to be close to residential areas anyway. The small modern wind generators used on boats and caravans make hardly any sound at all.

 
Is it renewable?  

Wind power is renewable. Winds will keep on blowing, it makes sense to use them.

Tidal power energy from the sea
Introduction

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The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy - around 20% of Britain's needs. Although the energy supply is reliable and plentiful, converting it into useful electrical power is not easy. There are eight main sites around Britain where tidal power stations could usefully be built, including the Severn, Dee, Solway and Humber estuaries. Only around 20 sites in the world have been identified as possible tidal power stations.

 
A few years ago, "tidal power" meant "tidal barrage". But these days there are other options as well.

 

How it works: Tidal Barrages

These work rather like a hydro-electric scheme, except that the dam is much bigger. A huge dam (called a "barrage") is built across a river estuary. When the tide goes in and out, the water flows through tunnels in the dam. The ebb and flow of the tides can be used to turn a turbine, or it can be used to push air through a pipe, which then turns a turbine. Large lock gates, like the ones used on canals, allow ships to pass. If one was built across the Severn Estuary, the tides at Weston-super-Mare would not go out nearly as far there'd be water to play in for most of the time. But the Severn Estuary carries sewage and other wastes from many places (e.g. Bristol & Gloucester) out to sea. A tidal barrage would mean that this stuff would
 

hang around Weston-super-Mare an awful lot longer! Also, if you're one of the 80,000+ birds that feeds on the exposed mud flats when the tide goes out, then you have a problem, because the tide won't be going out properly any more.

Video clip: Tidal barrage, Rance Estuary, France More:

The largest tidal power station in the world (and the only one in Europe) is in the Rance estuary in northern France, near St. Malo. It was built in 1966.

A major drawback of tidal power stations is that they can only generate when the tide is flowing in or out - in other words, only for 10 hours each day. However, tides are totally predictable, so we can plan to have other power stations generating at those times when the tidal station is out of action.

 
 

There have been plans for a "Severn Barrage" from Brean Down in Somerset to Lavernock Point in Wales. Every now and again the idea gets proposed, but nothing has been built yet. It would cost at least £15 billion to build, but other figures about the project seem to vary depending on where you look. For example, one source says the Severn Barrage would provide over 8,000 Megawatts of power (that's over 12 nuclear power station's worth), another says it would be equivalent to 3 nuclear power stations. The variation in the numbers is because there are several different Severn Barrage projects being proposed, so be careful about which numbers you quote if you're a student researching this topic. There would be a number of benefits, including protecting a large stretch of coastline against damage from high storm tides, and providing a ready-made road bridge. However, the drastic changes to the currents in the estuary could have huge effects on the ecosystem, and huge numbers of birds that feed on the mud flats in the estuary when the tide goes out would have nowhere to feed.
Find out more at:

• •

www.bbc.co.uk/insideout/   en.wikipedia.org/wiki/Severn_Barrage  

Another o option is to us se offshore t turbines, rathe like an er

underwat wind farm. ter . This has t advantage of being the much che eaper to build, and does not have the environm mental problems that a tidal barrage would brin ng. There are also many more e m suitable s sites. Find out more at www.mar rineturbines.c com

 

   

Th University o Wales Swa he of ansea and pa artners are als so res searching tec chniques to ex xtract electrica energy from al m flow wing water. Th "Swanturbines" design is different to other devices in he s an number of wa ays. The most significant is that it is dire t s ect drive, where the blades are c e connected dir rectly to the ele ectrical gener rator without a gearbox bet tween. This is s mo efficient a there is no gearbox to g wrong. ore and o go An nother differen is that it u nce uses a "gravity base", a lar y rge concrete block t hold it to th seabed, ra to he ather than drill ling into the seabed. Finally, the blades are fix pitch, rath xed her tha actively co an ontrolled, this is again to de esign out components tha could be un at nreliable. Find out mor at www.swanturbines.co re o.uk
 

December 2 2008: A "Tidal Reef" across the Severn Estuary is being propos R e y sed.

At first glance this looks like a tidal barrage, but this design does not block the water movement as much, so it wouldn't affect the tides as severely and the environmental consequences would be much less. It could be built in sections, so power could start being generated sooner. Migratory fish could get through, mud flats could still be exposed at low tide, and it would be able to generate power for more hours in the tidal cycle. Sections of it would open to allow shipping through, and it could be used to control tidal levels further upstream, for example preventing storm surges from flooding low-lying land. (Author's note - I live on low-lying land near the Severn Estuary, so I'm quite keen on this!) Tidal barrages have been built before, whereas this idea is untested - so it'll be interesting to see if it gets approved.
Find out more at www.severntidal.com.

Yet another option: vertical-axis turbines

Find out more from the Canadian company Blue Energy at www.bluenergy.com

Advantages  

• • • • • • •

Once you've built it, tidal power is free. It produces no greenhouse gases or other waste. It needs no fuel. It produces electricity reliably. Not expensive to maintain. Tides are totally predictable. Offshore turbines and vertical-axis turbines are not ruinously expensive to build and do not have a large environmental impact.

Disadvantages

•

A barrage across an estuary is very expensive to build, and affects a very wide area - the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed. There are few suitable sites for tidal barrages. Only provides power for around 10 hours each day, when the tide is actually moving in or out.

•

Is it renewable?  

Tidal energy is renewable. The tides will continue to ebb and flow, and the energy is there for the taking.

Hydroelectric power energy from falling water 

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Introduction

We have used running water as an energy source for thousands of years, mainly to grind corn. The first house in the world to be lit by hydroelectricity was Cragside House, in Northumberland, England, in 1878. In 1882 on the Fox river, in the USA, hydroelectricity produced enough power to light two paper mills and a house. Nowadays there are many hydro-electric power stations, providing around 20% of the world's electricity. The name comes from "hydro", the Greek word for water.

   

How it works

A dam is built to trap water, usually in a valley where there is an existing lake. Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators. Notice that the dam is much thicker at the bottom than at the top, because the pressure of the water increases with depth. Hydro-electric power stations can produce a great deal of power very cheaply.

Video clip: Hydro power - how it works

 

 

When it was first built, the huge "Hoover Dam", on the Colorado river, supplied much of the electricity for the city of Las Vegas; however now Las Vegas has grown so much, the city gets most of its energy from other sources. There's a good explanation of how hydro power works at www.fwee.org. Although there are many suitable sites around the world, hydro-electric dams are very expensive to build. However, once the station is built, the water comes free of   charge, and there is no waste or pollution.

 

The Sun evaporates water from the sea and lakes, which forms clouds and falls as rain in the mountains, keeping the dam supplied with water. For free.

 

 

More:

Gravitational potential energy is stored in the water above the dam.
Video clip: Hoover Dam in 1 minute

Because of the great height of the water, it will arrive at the turbines at high pressure, which means that we can extract a great deal of energy from it. The water then flows

away downriver as normal. In mountainous countries such as Switzerland and New Zealand, hydro-electric power provides more than half of the country's energy needs. An alternative is to build the station next to a fast-flowing river. However with this arrangement the flow of the water cannot be controlled, and water cannot be stored for later use.

 
Advantages    

• • • • • •

Once the dam is built, the energy is virtually free.   No waste or pollution produced. Much more reliable than wind, solar or wave power. Water can be stored above the dam ready to cope with peaks in demand. Hydro-electric power stations can increase to full power very quickly, unlike other power stations. Electricity can be generated constantly.

   

Disadvantages

•

The dams are very expensive to build. However, many dams are also used for flood control or irrigation, so

building costs can be shared. • Building a large dam will flood a very large area upstream, causing problems for animals that used to live there. Finding a suitable site can be difficult - the impact on residents and the environment may be unacceptable. Water quality and quantity downstream can be affected, which can have an impact on plant life.

•

•

 
Is it renewable?  

Hydro-electric power is renewable. The Sun provides the water by evaporation from the sea, and will keep on doing so.

Pumped Storage Enter your search terms  Reservoirs storing energy Submit search form    to cope with big demands 
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Introduction

Pumped storage reservoirs aren't really a means of generating electrical power. They're a way of storing energy so that we can release it quickly when we need it. Demand for electrical power changes throughout the day. For example, when a popular TV programme finishes, a huge number of people go out to the kitchen to put the kettle on, causing a sudden peak in demand. If power stations don't generate more power immediately, there'll be power cuts around the country - traffic lights will go out, causing accidents, and all sorts of other trouble will occur. The problem is that most of our power is generated by fossil fuel power stations, which take half an hour or so to crank themselves up to full power. Nuclear power stations take much longer.
We need something that can go from nothing to full power immediately, and keep us supplied for around half an hour or so until the other power stations catch up. Pumped storage reservoirs are the answer we've chosen.

The UK has one in North Wales, at Dinorwic. There's an older one at Ffestiniog, also in North Wales.

 

How it works

Between 1976 and 1982 at Dinorwig, in North Wales, a huge project was built. Yet there's little to see as you drive past, as most of it is deep inside a mountain. Water is pumped up to the top reservoir at night, when demand for power across the country is low. When there's a sudden demand for power, the "headgates" (huge taps) are opened, and water rushes down the tunnels to drive the turbines, which drive the powerful generators. The water then collects in the bottom reservoir, ready to be pumped back up later.

 
Dinorwig has the fastest "response time"

of any pumped storage plant in the world - it can provide 1320 MegaWatts in 12 seconds. That's a lot of cups of tea!

 

More about Dinorwic

When water is pumped up to the top reservoir (called "Marchlyn Mawr") we are storing gravitational potential energy in it. The greater the height, the more energy is stored. This is one of the reasons that the Dinorwig site was chosen - there was a big height difference between two existing lakes, so less work was needed to build the station. The water falls 600 metres on its way to the turbines, so it's under a great deal of pressure when it arrives. For this reason, the tunnels are lined with steel at the bottom end. Each of the six generators is capable of producing 288 MegaWatts of power at 18,000 Volts, which is stepped up to 400,000 Volts by transformers and sent along underground cables to be fed into the "supergrid", which is the long-distance network of the National Grid. Dinorwig has "pump/turbines", which can be used both as pumps for getting water from the lower to the upper reservoirs, and as turbines for generating electrical power.

Here are two video clips from First Hydro, the company that operates Dinorwig. They're a bit long, but they do tell you a great deal about how the station was built and how it works:

Video clip: Electric Mountain part 1 (7 mins 28 sec)

There is a complex system of gutters in the roof of the caves, to collect water that drips down through the rock. Carol Vordeman worked on this part of the station - helping to design this was one of her first engineering jobs before she moved into television.

 

Video clip: Electric Mountain part 2 (6 mins 3 sec)

You can find out more about the Dinorwig station from First Hydro's web site  

 
Advantages    

•

Without some means of storing energy for quick release, we'd be in trouble. Little effect on the landscape. No pollution or waste

• •

 

Disadvantages

• •

Expensive to build. Once it's used, you can't use it again until you've pumped the water back up. But the industry is very good at predicting when the surges in power demand will happen, so good planning can get around this problem

Is it renewable?  

It's not really a power station, but a means of storing energy from other power stations. So the question doesn't apply.

Energy Resource    s: Wave power

 

 

 

 

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Introduction  

Ocean waves are caused by the wind as it blows across the sea. Waves are a powerful source of energy. The problem is that it's not easy to harness this energy and convert it into electricity in large amounts. Thus, wave power stations are rare.

 

How it works

There are several methods of getting energy from waves. One of them works     like a swimming pool wave machine in reverse. At a swimming pool, air is blown in and out of a chamber beside the pool, which makes the water outside bob up and down, causing waves. At a wave power station, the waves arriving cause the water in the chamber to rise and fall, which means that air is forced in and out of the hole in the top of the chamber. We place a turbine in this hole, which is turned by the air rushing in and out. The turbine turns a generator. A problem with this design is that the rushing air can be very noisy, unless a silencer is fitted to the turbine. The noise is not a huge problem anyway, as the waves make quite a bit of noise themselves.
 

 

 
Example:

A company called Wavegen operate a commercial wave power station called "Limpet" on the Scottish island of Islay.
Find out more at www.wavegen.co.uk...

View an animat ion about how "Limpet" works from the Greenpeace website. Not working? Try this copy of the animation...

 
Example:  

A company called Ocean Power Delivery are developing a method of offshore wave energy collection, using a floating tube called "Pelamis". This long, hinged tube (about the size of 5 railway carriages) bobs up and down in the waves, as the hinges bend they pump hydraulic fluid which drives generators.
Find out more, including an interactive model, videos and technical details at www.oceanpd.com...

 
Video clip: How Pelamis works
 

 

 
Example:   Video Clip: CETO

Another company is called Renewable Energy Holdings. Their idea for generating wave power (called "CETO") uses underwater equipment

on the sea bed near the coast. Waves passing across the top of the unit make a piston move, which pumps seawater to drive generators on land. They're also involved with wind power and biofuel.

 

More

More ideas about how to extract energy from waves are being proposed all the time. This page only shows three examples. Once you've built a wave power station, the energy is free, needs no fuel and produces no waste or pollution. One big problem is that of building and anchoring something that can withstand the roughest conditions at sea, yet can generate a reasonable amount of power from small waves. It's not much use if it only works during storms!

 

Advantages    

• • •

The energy is free - no fuel needed, no waste produced. Not expensive to operate and maintain. Can produce a great deal of energy.

Disadvantages  

•

Depends on the waves sometimes you'll get loads of energy, sometimes almost nothing. Needs a suitable site, where waves are consistently strong. Some designs are noisy. But then again, so are waves, so any noise is unlikely to be a problem. Must be able to withstand very rough weather.

•

 

•

•

Is it renewable?  

Wave power is renewable.

 

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Geothermal - heat from underground

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Introduction

The centre of the Earth is around 6000 degrees Celsius easily hot enough to melt rock. Even a few kilometres down, the temperature can be over 250 degrees Celsius. In general, the temperature rises one degree Celsius for every 36 metres you go down. In volcanic areas, molten rock can be very close to the surface. Sometimes we can use that heat. Geothermal energy has been used for thousands of years in some countries for cooking and heating. The name "geothermal" comes from two Greek words: "geo" means "Earth" and "thermal" means "heat".

   

How it works

Hot rocks underground heat water to produce steam. We drill holes down to the hot region, steam comes up, is purified and used to drive turbines, which drive electric generators. There may be natural "groundwater" in the hot rocks anyway, or we may need to drill more holes and pump water down to them.

 
The first geothermal power station was built at Landrello, in Italy, and the second was at Wairekei in New Zealand. Others are in Iceland, Japan, the Philippines and the United States. In Iceland, geothermal heat is used to heat houses

 

as well as for generating electricity. If the rocks aren't hot enough to produce steam we can sometimes still use the energy - the Civic Centre in Southampton, England, is partly heated this way as part of a district heating scheme with thousands of customers..

 

Video clip: Geothermal energy - it's hot! 

 

 

More

Geothermal energy is an important resource in volcanically active places such as Iceland and New Zealand. How useful it is depends on how hot the water gets. This depends on how hot the rocks were to start with, and how much water we pump down to them. Water is pumped down an "injection well", filters through the cracks in the rocks in the hot region, and comes back up the "recovery well" under pressure. It "flashes" into steam when it reaches the

Video clip: How geothermal energy works

surface. The steam may be used to drive a turbogenerator, or passed through a heat exchanger to heat water to warm houses. A town in Iceland is heated this way. The steam must be purified before it is used to drive a turbine, or the turbine blades will get "furred up" like your kettle and be ruined.
See Also:

A diagram showing a geothermal project http://www.geothermal.marin.org/GEOpresentation/sld037.htm Types of geothermal power plants: www1.eere.energy.gov/geothermal/powerplants.html

   
Advantages    

•

Geothermal energy does not produce any pollution, and does not contribute to the greenhouse effect. The power stations do not take up much room, so there is not much impact on the environment. No fuel is needed. Once you've built a geothermal power station, the energy is almost free. It may need a little energy to run a pump, but this can be taken from the energy being generated.

•

 

• •

 

Disadvantages

•

The big problem is that there are not many places where you can build a geothermal power station. You need hot rocks of a suitable type, at a depth where we can drill down to them. The type of rock above is also important, it must be of a type that we can easily drill through. Sometimes a geothermal site may "run out of steam", perhaps for decades. Hazardous gases and minerals may come up from underground, and can be difficult to safely dispose of.

• •

Is it renewable?

Geothermal energy is renewable. The energy keeps on coming, as long as we don't pump too much cold water down and cool the rocks too much.

Biomass energy from organic materials
Introduction    

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Wood was once our main fuel. We burned it to heat our homes and cook our food. Wood still provides a small percentage of the energy we use, but its importance as an energy source is dwindling. Sugar cane is grown in some areas, and can be fermented to make alcohol, which can be burned to generate power. Alternatively, the cane can be crushed and the pulp (called "bagasse") can be burned, to make steam to drive turbines. Other solid wastes, can be burned to provide heat, or used to make steam for a power station. "Bioconversion" uses plant and animal wastes to

 

produce "biofuels" such as methanol, natural gas, and oil. We can use rubbish, animal manure, woodchips, seaweed, corn stalks and other wastes.

 
Video clip: Why use biomass? 
 

 
 

How it works
For a biomass power station making electricity, it's pretty much like a fossil fuel power station:

For other biofuels, we may burn it to get the heat for our home, or burn it to get energy for a car engine, or for some other purpose.

 
More

Sugar cane is harvested and taken to a mill, where it is crushed to extract the juice. The juice is used to make sugar, whilst the left-over pulp, called "bagasse" can be burned in a power station. The station usually provides power for the sugar mill, as well as selling electricity to the surrounding area. 2008: plans have just been announcedby trhe energy company E.on for a biomass-fuelled power station Portbury, near Bristol. The fuel would be wood, brought in by boat, and the station would produce 150MW of electrical power. Find out more It is claimed that biofuels will help us to reduce our reliance on fossil-fuel oil, and that this is a good thing. On the other hand, it is also claimed that it takes a huge amount of land to grow enough

Is biomass all good news? Video clip: Biomass? Maybe...

crops to make the amount of biofuels we'd need, so much so that it makes a big dent in the amount of land available for growing food. Who is right? Should we be using more biofuels and less fossil fuels? Think about the carbon dioxide - there are similar CO emissions from biofuel-powered vehicles as from petrol-powered ones.
2

It is claimed that growing plants to make biofuels will take in that carbon dioxide again. But biologists tell us that forests are not 'the lungs of the planet' after all - they give out as much CO as they absorb as the plants respire. It seems that it's plant plankton in the oceans that takes in most CO and gives out most oxygen.
2 2

Don't just take my word for any of this - I'm not an expert. Find out more for yourself!
See also:
Could you use biomass to fuel your home? Visit www.energysavingtrust.org

 
Advantages    

• • •

It makes sense to use waste materials where we can. The fuel tends to be cheap. Less demand on the fossil fuels.

 

Disadvantages

• • •

Collecting or growing the fuel in sufficient quantities can be difficult. We burn the biofuel, so it makes greenhouse gases just like fossil fuels do. Some waste materials are not available all year round.

 

Is it renewable?

Biomass is renewable, as we're going to carry on making waste products anyway. We can always plant & grow more sugar cane and more trees, so those are renewable too.