Wind Energy in America

Growth of Renewable Energy:
Incompatible with the Modern Grid













Clean Energy 110
3/12/14

Renewable energy produces a growing percentage of the electricity on the American
power grid causing unforeseen issues associated with the irregular power output of
renewable energy. Production of renewable energy technologies are moving out of the small
residential market and into large-scale projects with the goal of shipping power nationwide
via the existing power distribution network. The problem with electricity is its shelf life,
essentially zero, the power generated by power plants (conventional or renewable) must be
used instantly or it risks damaging the grid. Washington state’s energy production ranks
among the top in the nation which is great news for the environment however presents
technical nightmares for those responsible for providing reliable electricity. Growing
awareness within the industry is fostering research and growth for energy storage projects
that could compensate for the fluctuations presented by renewable power.

Growth of Renewable Energy
Renewable energy is nothing new, hydro-electric power plants have producing
electricity for decades. Wind and solar technologies have also been proven effective in small-
scale operations. Companies are looking at wind and solar power and producing facilities
worldwide that can harness the limitless potential and convert it into usable electricity. A
yearly energy breakdown from the U.S. Energy Information Administration (EIA) shows the
growth of renewable electricity since 1950, presented in Trillions of BTU (converted using
fossil fuels heat rate). During that time the renewable sector as a whole has grown by over
300%. In 1950 the yearly renewable energy output was 2,978 trillion BTU, the majority of
which came from hydro-electric at 1,415 trillion and Biomass (wood) at 1,562 trillion, at its
peak in 2011 the U.S. produced 9,704 trillion BTU of renewable energy coming from a
combination of hydro-electric, geo-thermal, solar/pv, wind, and bio-mass(wood, waste, and
bio-fuels). Of the renewable sources featured in the report the largest growth by far has been
in wind energy. Wind went unreported until 1985 when it produced less than .5 trillion BTU,
28 years later in 2013 wind power generated the electrical equivalent of 1461 trillion BTU.
The growth of wind energy is the fastest growing renewable power technology rivaled only by
the technological advances in bio-fuels.
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The Pacific Northwest prides itself on being the greenest region when it comes to
power generation. In 2010, 72.4% of Washington state’s electricity was generated by
renewable sources. The majority of that came from the state’s hydro-electric plants which
produced 68,288 thousand megawatthours (MWh). The second highest yielding renewable
source was wind, boasting almost 5% of the state’s annual production.
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This is great news
isn’t it? Not so fast, harvesting clean energy is always beneficial to the environment, however
fluctuating output from renewable sources presents issues when trying to connect to the very
delicate power grid.

Electrical Power Grid
In order to fully understand the implications renewable energy can have on a power
grid it is necessary to have a basic knowledge of America’s power distribution system. ‘The
Grid’ as it is often referred to is a complicated web of interconnected systems broken into
three main sections, the Eastern Interconnection, the Texas Interconnection, and the Western
Interconnection spans the western states as far as Wyoming, Colorado, and Montana. The
Western Interconnection uses transmission lines to transport three-phase alternating current
(AC) at high voltages between 230,000 and 765,000 volts. In addition the Western
Interconnection boasts the nations longest HVDC (High voltage direct current) line which
transmits enough clean energy from the Pacific Northwest’s Bonneville Power Association
(BPA) to provide electricity for two to three million homes in the Los Angeles area.
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Maintaining the Western Interconnection is the responsibility of various councils and
companies who buy and sell power via these lines.
The grid needs to be constantly monitored and tuned in order to keep power
production and demand in balance. Not enough power results in blackouts for entire cities;
too much power can overload the system and damage power stations across an entire region.
Maintaining this balance is easy when using conventional power plants such as coal, natural
gas, or nuclear. These plants are reliable in the amount of energy they produce and energy
companies need reliable outputs when trying to keep the grid balanced. Natural gas power
plants can be switched on and off as needed throughout the day, for example power
companies will turn on their plants in the middle of the night because they know people will
be getting up for work in a few hours and the demand for energy will grow very quickly at
around 6am.

Monitoring the Grid
Some renewable energy sources present a unique problem which stems from its
irregular energy output. Washington State presents a good example for the steps needed to
maintain a balanced grid. Washington’s hydro-electric capabilities provide a great baseline
energy source by providing say 75% of its energy needs, other states this energy source may
be coal, natural gas, nuclear, or a combination. This leaves 25% that needs to be produced by
other energy sources and the goal is to maximize the production of renewable sources.
Currently 5% of the yearly energy demands in Washington are met by wind power, 7.5%
during the summer. This leaves another 20% of the state’s energy needs to be produced by
other means. The grid is consumes the 5% it is getting from wind, the electricity comes in and
mixes in with hydro electricity and nuclear electricity, and then suddenly the wind stops
blowing and the grid is operating at only 95%. The grid then has to quickly find electricity to
fill that 5% somewhere else or risk blackouts.
In an effort to combat sudden drops in wind power, the companies need to have
backups. Conventional power sources, usually large generators, are kept on standby
whenever wind power is being used because of the risk that the wind will stop. The question
is asked cant the power companies predict the wind in order to prepare? The simple answer
is no, in the graph below the relationship between forecasted wind production and actual
production is not reliable. The difference between predicted and actual production in the
graph exceeds 1500 MegaWatts, too much electricity for the grid to simply compensate.
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There is a well-known industry example of a German wind company called E.ON that was
subject to a large wind disturbance on Christmas Eve of 2004. This is a quote from their
report of the incident.
“Whilst wind power feed-in at 9.15 am on Christmas Eve reached its maximum
for the year at 6,024MW, it fell to below 2,000MW within only 10 hours, a difference of
over 4,000MW. This corresponds to the capacity of 8 x 500MW coal fired power station
blocks. On Boxing Day, wind power feed-in in the E.ON grid fell to below 40MW.
Handling such significant differences in feed-in levels poses a major challenge to grid
operators.”
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Summarizing, the disturbance, unpredictable with modern forecasting techniques, very
quickly affected the company’s energy production. In order to compensate for the sudden loss
in power the operator needed to act quickly to route power from other sources. As mentioned
before the wind companies need conventional backups which remain offline for the most part
for use in emergencies like this one. These backups are normally sized to quickly compensate
for 90% of the wind capacity, they are also expensive and contribute to carbon emissions.
5

In contrast to the problems that arise when wind is not available, there are situations
where renewable resources are overproducing, especially in Washington. Wind and hydro-
electric power capabilities vary greatly depending on the season. Spring time is great for
harvesting renewable energy, snow melt offers plenty of water for hydro-electric plants at the
same time fast steady winds present the opportunity for large amounts of wind energy to be
captured. In fact wind and hydro-electric potential alone outweighs the maximum load for the
local grid. This leaves few options for the power companies, shutting down the hydro-electric
plants is not an option because melting snow pack will continue to fill the Columbia river and
could overflow the dams, also salmon downstream would not have enough water to make it
up river. The only other option is called ‘wind dumping’ or ‘feathering’ where wind farms are
essentially taken offline because their power is simply not needed.
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This presents some big
issues if you own a company that just invested millions into a large-scale wind farm. This
quote from the e-magazine intelligent energy details the wind companies take on the matter.
“The shutdowns, according to BPA, have cut wind generation by 15 percent. In
addition to wind, the utility is not currently taking in coal, natural gas or nuclear
power. Those facilities, however, can conserve their fuel resources in the interim.
When the wind blows and there's no turbine to catch it, it still blows. And it does blow
for wind companies, which are losing profits, production-based government
incentives, and possibly, investment prospects. They have calculated their damages in
the millions.”
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Legal action is being taken against BPA and other similar situations are playing out nation
wide.

Energy Storage Solutions
Energy companies are realizing that wind dumping is basically free money blowing
away in the wind and they are investing in energy storage techniques. The U.S. has
implemented 5 main large-scale energy storage techniques.
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-Thermal storage or thermal-chemical storage
-Battery storage
-Compressed air storage
-Flywheel or kinetic storage
-Pumped hydro-electric
Pumped hydro-electric is the most widely used form of mass energy storage and has
an estimated potential of 20 GigaWatts nationally. The idea is simple, use the excess
electricity produced in peak seasons to pump water to a reservoir at a higher elevation. As the
demand for energy increases the stored water is ran through a conventional hydro-electric
system to create electricity. Increasing the nation’s mass energy storage capabilities removes
the limiting factors presented by the aging power grid and can allow for renewable energy
production outside of the previously considered ‘peak season’.
3
Another 31 GW of proposed pumped hydro-electric storage will be available for
American consumers within the coming years. 15GW have already been approved by the
Federal Energy Regulatory Commission (FERC) and another 16 GW are waiting approval.
3

The only pumped hydro-electric storage in Washington right now is located at the Grand
Coulee dam and produces an estimated 314 MW of electricity, small in comparison to Bath
County, West Virginia’s storage facility of 2100MW. The Grand Coulee program is also praised
for its ability to regulate water flow in order to maintain safe breeding conditions for salmon.
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The only other mass energy storage facility in the United States is the SustainX
compressed air system in New Hampshire. Produced mostly for research purposes it only
stores 1.65 MW of power and it cost over $5 million dollars making it less popular on a large
scale.
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Growth in renewable energy should not be stifled by its incompatibility with the
modern electrical grid. By implementing mass energy storage, renewable energy will only
grow as it becomes easier to use in our already developed electricity network. Building and
researching new storage systems increases the potential of renewable sources and will help
to reduce our dependence on conventional fossil and nuclear fuels.













Sources
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