Overview of Carbon Footprint

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Carbon footprint (CF)-also named Carbon profile-is the overall amount of carbon dioxide and other greenhouse gas (GHG) emissions (e.g. methane, laughing gas, etc) associated with a product, along its supply-chain and sometimes including from use and end-of-life recovery and disposal

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INTRODUCTION
What is a carbon footprint?

Carbon footprint (CF)-also named Carbon profile-is the overall
amount of carbon dioxide and other greenhouse gas (GHG)
emissions (e.g. methane, laughing gas, etc) associated with a
product, along its supply-chain and sometimes including from use
and end-of-life recovery and disposal. Causes of these emissions
are, for example, electricity production in power plants, heating
with fossil fuels, transport operations and other industrial
processes.
The carbon footprint is quantified using indicators such as the
Global

Warming

Potential

(GWP).

As

defined

by

the

Intergovernmental Panel on CLIMATE Change (IPCC), a GWP is an
indicator that reflects the relative effect of a greenhouse gas in
terms of climate change considering a fixed time period, such as
100 years (GWP100). The GWPs for different emissions (see Table 1)
can then be added together to give one single indicator that
expresses the overall contribution to climate change of these
emissions.

How can I measure the carbon footprint of my product?
The carbon footprint is a sub-set of the data covered by a more
complete Life Cycle Assessment (LCA). LCA is an internationally
1

standardized method (ISO 14040, ISO 14044) for the evaluation of
the environmental burdens and resources consumed along the life
cycle of products; from the extraction of raw materials, the
manufacture of goods, their use by final consumers or for the
provision of a service, recycling, energy recovery and ultimate
disposal.
One of the key impact categories considered in an LCA is climate
change, typically using the IPCC characterization factors for
carbon dioxide equivalents.

Hence, a carbon footprint is a life

cycle assessment with the analysis limited to emissions that have
an effect on climate change. Suitable background data sources for
the footprint are therefore those available in existing LCA
databases. These databases contain the life cycle profiles of the
goods and services that you purchase, as well as of many of the
underlying

materials,

energy

sources,

transport

and

other

services.
Table 1: Global warming potentials of some Greenhouse
Gases (source: IPCC,
2007)
Species

Chemical formular
CO2

Carbon dioxide

GWP100
1

Methane

CH4

25

Nitrous oxide

N2 O

298

2

HFCs

-

124 - 14800

SF6
Sulphur

22800

hexafluoride
PFCs

Why

the

evaluation

7390 - 12200

must

be

broadened

to

avoid

misleading results and wrong decision?
Although building upon a life cycle approach, carbon footprints
address only impacts on climate change. When exclusively carbon
footprint data are used to support procurement decisions or to
improve goods and services, other important environmental
impacts are neglected while often running opposite to climate
change, resulting in a “shifting of burdens”. Achieving sustainable
consumption and production requires the consideration and
evaluation of all relevant environmental impacts at the same
time, such as e.g. acid rain, summer smog, cancer effects and
land use. This can only be ensured by the more complete Life
Cycle Assessment.
If organizations are now developing carbon footprint data, then it
makes sense to evaluate also relevant non-greenhouse gas
emissions (e.g. NOx, particles, SO 2) along the product supply

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chain or full life cycle. The in-house effort is only slightly higher
and same background data sources will be used.

Are there standards or guidelines to perform carbon
footprint calculations?
The international standards ISO 14040-14044 provide robust and
practice-proven requirements for performing transparent and
accepted carbon footprint calculations. Over the past ten years, a
wide consensus on climate change evaluations in this life cycle
context has been built up in the scientific community and has
successfully been applied by many leading companies in all
sectors. In a policy context, the carbon footprint can be seen as a
subset of the growing demand for life cycle based information
that is being used for knowledge-based decision making in the
context of sustainable consumption and production.
ISO standards also support specific communication needs on
climate change topics. The ISO type I Eco-labels and type III
Environmental Product Declarations are the best reference
framework for third party verified claims on carbon performance
of products. We note here the importance of critical third-party
reviews to help ensure problems do not arise later.

4

TOP SOURCES OF GREEN HOUSE GAS EMISSIONS
Power: Today hundreds of aged power plants release large
volumes of green house gases (GHGs) while supplying electricity
for U.S. These seldom top 38% thermal efficiency even though
technologies

exist

that

can

better

50%.

A

1%

efficiency

improvement out of 26 quadrillion Btu conversion losses from U.S.
power production would result in savings of 260 trillion Btu, an
equivalent

of

GHG

emissions

from3.5-million

passenger

automobiles.
Integrated gasification, combined-cycle (IGCC) leads the list of
solutions to this problem. IGCC combines two thermodynamic
cycles: a gas combustion cycle and a steam cycle, each with its
own turbine and generator. Natural gas or coal gasification
provides energy for the first cycle. Heat from the flue of the first
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cycle is used to generate superheated steam to drive the second
set of turbines. Larger temperature differences between the hot
and cold ends of the combined cycle allow higher thermal
efficiency relative to single cycles, netting benefits of 20% less
GHG and 20-40% lower water usage.
IGCC capacity planned for 2014 is 14.8 GW with 27 projects in 16
states. Worldwide, nearly 4 GW of IGCC currently operate and 50
new projects totaling 27 GW have been announced.
Ocean and terrestrial (vegetation and soils) CO 2 sequestration are
being investigated. The environmental impact of these methods is
unknown at this. CO2 storage in soils as magnesium carbonates or
as CO2 clathrate are promising as safe, solid materials offering
compact storage with potential commercial value.

Transportation fuels: Transportation fossil fuels release the
second largest volume of GHGs. Renewable fuels (bio-ethanol and
biodiesel) are leading solutions reducing GHGs from 7 to 90% per
gallon, compared to gasoline, depending on feedstock and
process type, according to Argonne National Laboratory. Applying
the low end of this range to the 160-billion gal/yr of gasoline
consumed in the U.S., 133-million tons of CO 2 emissions would be
prevented. For companies interested in bio-fuels production, an
excellent repository of reports and models is accessible at the
National Renewable Energy Laboratory’s (NREL) website.

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Industry, including chemicals: Energy consumption per unit of
chemical output decreased 40% between 1974 and 1990. Since
1990 however, improvement slowed to a relatively flat rate. In
2005, Oak Ridge National Laboratory reported possible energy
savings for the twelve largest energy users in chemicals totaling
252 trillion Btu/yr. Paper, ethylene, oxygen, ammonia and styrene
lead the list (in that order) with 219 trillion Btu.
Chemical Industry Vision2020 and the U.S. Department of Energy
(DOE) estimate inefficiencies of 2.7 quadrillion Btu in the chemical
industry, and estimate that innovations could cost-effectively
achieve 30% improvement by 2020 or 750 trillion Btu/yr, an
equivalent to emissions from 9 million passenger cars – enough to
account for most cars in New York City, Los Angeles, Chicago, and
Houston combined.
Many companies responded early to the challenge: Boise Cascade
generates 54% of its energy needs from renewable resources;
Dow Chemical built seven new cogeneration power facilities
since 1994 that reduced usage by approximately 23 trillion Btu/yr,
eliminating

approximately

1.2

million

metric

tons

of

CO 2

emissions.
Another development is significant investment in bio-refining.
Archer Daniels Midland recently launched commercialization of
biochemical replacements for petroleum-derived chemicals and
stated its intentions to develop new chemicals with increased
functionality and lesser environmental impact.
7

In general there two major ways that green house gases enter the
atmosphere, namely:
-Natural processes
-Human activities
Natural processes: Green house gases are released into the
atmosphere through natural processes such as animal and plant
respiration, ocean-atmosphere exchange soil respiration and
decomposition and volcanic eruptions. The amount of carbon
dioxide produced by natural sources is completely offset by
natural carbon sinks and has been for thousands of years. Before
the influence of humans, carbon dioxide levels were quite steady
because of this natural balance.
Human

activities:

Since the industrial revolution, human

sources of CO2 and other greenhouse gases has been growing.
The main human sources of greenhouse gas emissions are: fossil
fuel use such as the combustion of fuels for electricity, steam and
heat generation, combustion of fuels for transportation, intensive
livestock farming, use of synthetic fertilizers and industrial
processes.

THE ROLE OF CHEMICAL ENGINEERS IN REDUCING THE
CARBON FOOTPRINT

8

In manufacturing, the most common way to reduce the carbon
footprint is by reducing, reusing, and recycling of refuse. This can
be achieved by recycling the packing materials, by selling the
obsolete inventory of one industry to the industry who is looking
to buy unused items at lesser price to become competitive.
Nothing should be disposed off into the soil; all the ferrous
materials which are prone to degrade or oxidize with time should
be sold as early as possible at reduced price. This can be done by
using reusable items such as thermoses for daily coffee or plastic
containers for water and other cold beverages rather than
disposable ones. If that option isn’t available, it is best to properly
recycle the disposable items after use. When one household
recycles at least half of their household waste, they can save 1.2
tons of carbon dioxide annually.
Another easy option is to drive less. By walking or biking to the
destination rather than driving, not only is a person going to save
money on gas, but they will be burning less fuel and releasing
fewer emissions into the atmosphere. However, if walking is not
an option, one can look into carpooling or mass transportation
options in their area.
Chemical engineers play a leading role in the design and
implementation of effective technology-based solutions to control
CO2 emissions. Some of the technologies in place include:
-Cleaner burning fuels and alternative fuel strategies
-Catalytic converters
9

-Carbon Capture and Storage
-Advanced combustion systems
CLEANER BURNING FUELS AND ALTERNATIVE FUELS
STRATEGIES
Chemical engineers help reduce automotive air pollution through
advanced petroleum refining techniques. One example is hydro
treatment, which uses hydrogen gas and a catalyst to produce
gasoline and diesel fuel with significantly lower levels of sulfur

and lead. These techniques have made it possible to
produce reformulated fuels that function as effectively as
earlier leaded fuels, while releasing fewer pollutants.
An alternative fuel, most generally defined, is any fuel
other than the traditional selections, gasoline and diesel,
used to produce energy or power. The emissions impact
and energy output provided by alternative fuels varies,
depending on the fuel source. Examples of alternative
fuels include biodiesel, ethanol, electricity, propane,
compressed natural gas, and hydrogen.
Alternative fuels being used in transportation are briefly described
below:
Biodiesel is a clean burning, renewable alternative fuel that can
be produced from a wide range of vegetable oils and animal fats.
10

Biodiesel contains no petroleum, but can be blended at any level
with petroleum diesel to create a biodiesel blend. It can be used
in compression-ignition (diesel) engines with little or no
modifications.
Ethanol is a renewable alternative biofuel made from various
plant materials. Ethanol can be blended with gasoline in varying
quantities; most spark-ignited gasoline-style engines will operate
well with mixtures of 10% ethanol (E10). E85, a mixture of 85%
ethanol and 15% unleaded gasoline, is an alternative fuel for use
in flexible fuel vehicles (FFVs).
Electricity used to power vehicles is provided by the electricity
grid and stored in the vehicle’s batteries. Vehicles that run on
electricity have no tailpipe emissions. Electric vehicles are not
currently available from the major auto manufacturers; most
electric vehicles have been converted by amateur mechanics.
Propane, also known as liquefied petroleum gas, is a by-product
of natural gas processing and crude oil refining. Propane is less
toxic than other fuels. It has a high octane rating and excellent
properties for spark-ignited internal combustion engines. C
urrently, less than 2 percent of U.S. propane consumption is used
for transportation; however, interest is growing due to its
domestic availability, high energy density and clean-burning
qualities.
Compressed Natural Gas (CNG) is a natural gas that is
extracted from wells and compressed. Natural gas is a fossil fuel
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comprised mostly of methane and is cleaner burning than
gasoline or diesel fuel. Natural gas vehicles have been found to
produce less greenhouse gas emissions than gasoline vehicles,
but very little natural gas consumption is currently used for
transportation fuel.
Hydrogen (H2) is a renewable, domestically-produced, alternative
fuel that can be used to create electricity. A chemical reaction
between oxygen and hydrogen produces the electric power, and
when the transportation fuel is pure hydrogen, the only resulting
emission is water vapour. Depending on the energy source that
causes the chemical reaction, hydrogen can be an emission-free
transportation fuel. Not widely used today, current government
and industry research and development are investigating safe and
economical hydrogen production and hydrogen vehicles.
CATALYTIC CONVERTERS
Cars, trucks, and buses are essential for transportation and freight
delivery around the world. However, the exhaust from the
gasoline and diesel powered engines required to propel these
vehicles has been a major cause of air pollution.
The catalytic converter is considered one of the most important
contributions to the field of air-pollution control. It is now a
standard feature on vehicles everywhere. It destroys the three
main pollutants found in engine exhaust (i.e. CO, NOx and
unburned hydrocarbons-most often in particulate matter). The
converter consists of a porous honeycomb ceramic base material
12

coated with a precious metal catalyst. The honeycomb structure
provides high catalyst surface area, which maximizes the contact
between the catalysts and the pollutants in the hot exhaust
gases.
When this novel structure was first invented, it featured two
distinct chemical engineering advantages:
1. It maximized the amount of catalyst-coated surface area to
which the engine exhaust may be exposed.
2. It minimized the amount of expensive precious metal
catalyst required.
CARBON CAPTURE AND STORAGE (CCS)
CCS offers the potential for moving towards near-zero emissions
to the atmosphere from coal-fired and gas-fired power stations.
The scale of the potential has been outlined by the IPCC, which
has stated: “in most scenarios for stabilization of atmospheric
greenhouse gas concentrations between 450 and 750ppmv CO 2
and in a least-cost portfolio of mitigation options, the economic
potential of CCS would amount to 220-2200 Gigatonnes (Gt) CO 2
cumulatively, which would mean that CCS contributes 15-55% to
the cumulative mitigation effort worldwide until 2100” [IPCC
2005].
While CO2 capture technologies are new to the power industry
they have been deployed for the past sixty years by the oil, gas
and chemical industries. They are an integral component of
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natural gas processing and of many coal gasification processes
used for the production of syngas, chemicals and liquid fuels.
There are three main CO2 capture processes under development
for power generation namely:
Pre-combustion capture systems take the syngas produced
from coal gasification and convert it via a steam-based chemical
reaction into separate streams of CO2 and hydrogen. This
facilitates the collection and compression of the CO 2 into a
supercritical (fluid-like) form suitable for transportation and
geological storage.
Oxyfuel combustion involves combustion of coal in pure
oxygen, rather than air, to fuel a conventional steam generator.
By avoiding the introduction of nitrogen into the combustion
cycle, the amount of CO2 in the power station exhaust stream is
greatly concentrated, making it easier to capture and compress.
Post-combustion systems separate CO2 from the flue gases
produced by the combustion of coal in air. Post-combustion CO 2
capture technology, based on chemical absorption processes, is
already proven and commercially available in the oil and gas
industry. It is the closest to large –scale commercial deployment
for power generation but not yet at the scale required.
ADVANCED COMBUSTION SYSTEMS
The workhorse of America’s electric power is the coal fired power
plant. Today, coal combustion plants account for more than half of
14

the nation’s electric power generation. Largely because of these
plants, U.S. consumers benefit from some of the most affordable
power in the world.
The technology of burning coal has made remarkable advances in
the last quarter century and much of this progress is due to
federal research and development partnerships with private
sector developers.
In the 1900s, fluidized bed combustion (i.e. a process that
removes pollutants inside the coal boiler) was termed “the
commercial success story of the last decade “ by a major power
industry publication. The first new coal-fired power plant to be
built in Illinois in more than 15 years will employ a new type of
“low emission boiler” technology developed in the federal
government’s energy program. Innovations in burner designs,
refractory materials and high-temperature heat exchangers are all
products of the department of energy ‘s research program into
cleaner, more efficient ways to burn coal. A good example of an
advanced combustion system is a fluidized bed combustion
system.
Fluidized bed combustion (FBC)
Fluidized bed combustion (FBC) is a combustion technology used
to burn solid fuels. In its most basic form, fuel particles are
suspended in a hot, bubbling fluidity bed of ash and other
particulate materials (sand, limestone etc.) through which jets of
air are blown to provide the oxygen required for combustion or
15

gasification. The resultant fast and intimate mixing of gas and
solids promotes capable of burning a variety of low-grade solids
fuels, including most types of coal and woody biomass, at high
efficiency and without the necessity for thermal duty, FBCs are
smaller than the equivalent conventional furnace, so may offer
significant advantages over the latter in terms of cost and
flexibility. FBC reduces the amount of sulfur emitted in the form of
Sox emissions. Limestone is used to precipitate out sulfate during
combustion, which also allows more efficient heat transfer from
the boiler to the apparatus used to capture the heat energy
( usually water tubes). The heated precipitate coming in direct
contact with the tubes (heating by conduction) increased the
efficiency. Since this allows coal plants to burn at cooler
temperatures, less NOx is also emitted. However, burning at low
temperatures also causes increased polycyclic aromatic
hydrocarbon emissions. FBC boilers can burn fuels other than
coal, and the lower temperatures of combustion (800 0c/ 15000 F)
have other added benefits as well.

Conclusion
Global warming from the increase in greenhouse gases has
become a major scientific and political issue during the
past decade.All attempts have been made to reduce the
effect this has on the earth surface which has been
16

succinctly illustrated in this paper.Sources of greenhouse
gasse can come from burning of fossil
fuel,deforestation,farming,industrial waste and
landfills.The effect of greenhouse gas has been cotrolled

REFERENCES

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 Wright, L., Kemp, S., Williams, I. (2011) 'Carbon
footprinting': towards a universally accepted
definition. Carbon Management, 2 (1): 61-72.
 UK Carbon Trust (2008) "Carbon Footprinting".
 Parliamentary Office of Science and Technology POST
(2006). Carbon footprint of electricity generation.
October 2006, Number 268
 Wiedmann, T. and J. Minx (2008). A Definition of
'Carbon Footprint'. Ecological Economics Research
Trends. C. C. Pertsova: Chapter 1, pp. 1–11. Nova
Science Publishers, Inc, Hauppauge NY, USA. catalog
also available as ISA-UK Research Report 07/01
 World Energy Council Report (2004). Comparison of
energy systems using life cycle assessment.
 Energetics (2007). The reality of carbon neutrality.
 Walkers Carbon Footprint
 The LCA Resources Directory in Europe and beyond webpage
 http://lca.jrc.ec.europa.eu/lcainfohub//directory.vm


 European Platform on Life Assessment, European
Commission-Joint Research Centre Institute for Environment
and Sustainability
 http://lca.jrc.ec.europa.eu/
 http://lca.jrc.ec.europa.eu/EPLCA/mailing.htm

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