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Biofuel & Nuclear LCA: Setting the standard
Conventional resources are degrading at a fast and unrestorable pace. Non-conventional energy options are being sought. But what will be the result? LCA comes as a handy assessment tool in here.
Unregulated and uncontrolled use of the convention sources of energy are exhausting both resource reserve as well as clean environment. There is a need to use alternative and non-conventional sources of energy forms available to prevent the ongoing environmental degradation. Two such alternative energy forms are Bio-fuels and Nuclear energy. But before utilizing them, an end-use impact analysis is necessary.
There is a need to examine all the impacts of a product from production through use to disposal, including all resultant by-products. This can be done by conducting “Life Cycle Analysis”. LCA is based on “Cradle to Death Approach”. The best part of LCA is that it can be customized as per requirements, by limiting number of factor of analysis, based on aim and time/cost limitations.
The International Organization for Standardization (ISO), an international standard setting body has created a uniform set of broad guidelines for LCA and released as ISO 14040:2006. The standard is generalized in nature and applicable to any entity or institution, enabling meaningful comparisons across studies. ISO 14020 identifies four basic stages for the LCA to be conducted. It includes the defining the goal and scope, inventory analysis, impact assessment and interpretation.
Alternative energy forms can be assessed and their effect on environment can be analyzed by conduction LCA by taking into account two major factors i.e.the energy-source mix of India's electrical supply and the nature of India's energy infrastructure. The following two studies give a sense of the specific considerations for GHG and energy LCAs for Nuclear energy-electricity generation versus biofuel production (examining stage 1 and 2 only).
Liquid Biofuels: Jatropha Oil and Biodiesel
Jatropha fruits contains oil which can be extracted and refined into a stove kerosene-substitue or biodiesel. The major phases of the jatropha biodiesel life cycle include cultivation, transportation to production facilities, conversion to usable fuel product, end use, and production/use of co-products.
As with many biofuels, jatropha comes close to having a negative energy balance, using more fossil fuel energy to produce than the total energy available in the biofuel, so can increase atmospheric CO2. It may release more pollutants than equivalent fossil fuel, such as acid-rain causing chemicals. Yet with the right production methods, it could prove valuable, particularly in India. Each proposed Jatropha project should be pilot-tested to ensure widespread adoption of only those energy technologies that solve climate and/or energy supply concerns.
A few key aspects of each phase of special relevance in India:
Cultivation: The type of land utilized is a major determinant of Jatropha life-cycle GHG emissions and energy consumption. Living plant matter incorporates carbon from CO2 reducing its amount in atmosphere. If grown on marginal land with little prior vegetation and low food production potential, jatropha will increase this type of carbon sequestration. However, if grown on a previously high-plant-density area, the likely result is more net CO2 in the air. In India, it's is becoming an important substitute biofuel crops for food crops on the limited arable land of a high-population country. Unfortunately, the energy intensity is much better (lower) on fertile land, while an energy intensity greater than one is almost guaranteed in poor soil lacking irrigation.
Transport: The fuel mix used for transit in India and the distance of cultivation from the processing plant are the main considerations. Decentralized production in small facilities local to growing sites and the point of consumption reduces environmental costs of transport and allows ramping up production incrementally while experimenting with optimal production methods. However, small facilities may be less energy efficient than large centralized plants, or lack the capacity to convert byproducts to useful products.
Conversion: Extraction, refining, and trans-esterification (conversion to biodiesel) are powered by a mix of steam and electricity. Emissions and energy balance depend on the mix of fuel inputs. India's power system relies on about 60% coal, 25% hydroelectric, and 12% natural gas, and 3% nuclear (these figures vary somewhat among studies), with the rest from renewable energy such as wind and solar. A shift towards more low-fossil fuel electrical production would make jatropha biofuel less energy and GHG intensive.
End use: The environmental impacts and energy content of co-products must also be accounted for. The relevant point is how they compare to what they are substituting in the current market. Because India relies heavily on high emissions (GHG and pollutants) diesel fuel, Jatropha can be comparatively superior environmentally in India, while in Europe it would not be a major improvement on current liquid fuels. Impacts of co-products such as fertilizer, animal feed, and honey must similarly be compared to the products they would supplant.
Non-GHG considerations: Some studies suggest that Jatropha does worse than some equivalent fossil fuels on smog and acid rain effects. The LCA of these factors should be considered by decision makers; which concerns to prioritize is a policy question beyond the capacity of LCA.
LCA of Electrical Power Generation: Nuclear Plant
The energy intensity of electrical generation is usually calculated as kilowatt hours of thermal energy inputs divided by total kilowatts of electrical energy produced over the lifetime of the plant. In alternative energy, the electrical generators or power plants, the majority of energy consumption and greenhouse gas emissions happen upstream or downstream of on-site daily operations; the opposite is the case for fossil fuel power.
For a nuclear plant, the LCA covers nuclear plant construction (the life-cycle stage consuming the most fossil fuels); the mining of uranium (or other nuclear fuel); processing the uranium into usable fuel; plant operation; and disposal of radioactive wastes at all stages, from mining to decommissioning the plant at the end of its life.
According to a comprehensive literature review , a nuclear plants energy intensity usually ranges from .1-.3 kwh(thermal)/kwh(electric). The GHG from this process, measured in g CO2-equivalent/kWh(electric), depend heavily on the energy mix of the country.
Plant Construction: It takes many years of operation for a nuclear, solar, or wind electrical plant to "pay back" the large energy outlays demanded by plant construction alone. However, the long run payoff can be substantial, as many require little fossil fuel input for operation. One could use the power of an early alternative energy plants to fuel creation of later plants. However, during a rapid national project to replace coal-driven electricity, so much of the energy produced by early alternative plants would be eaten up by the creation of subsequent ones that the alternative energy would make no net contribution to the country's energy supply for years. For a country like India with only a modest nuclear/wind/solar infrastructure and rapidly growing electrical demands, this is a serious concern. Choosing options with lower construction energy inputs could be worthwhile even if the total life-cycle energy intensity and GHG emissions were less optimal.
Nuclear Fuel Extraction: The uranium content (grade) of the ore can also make or break a nuclear plant's climate-impact advantage over a coal plant. A plant run on low-grade ore can easily generate less electricity than we could have obtained from the fossil fuels used to produce the nuclear electricity production. The probable decline in global uranium quality over time is likely to degrade the GHG and energy efficiency advantages of nuclear fission. Some scientists are optimistic about the future of nuclear fusion or breeder reactors which could mitigate the problem, but the technology may not be ready soon enough to help stop global warming.
LCA, Life-cycle analyses demands comprehensive consideration of the unique relevant factors for each energy type. Ongoing tests of various alternative energy production methods accompanied by careful, country-specific GHG and energy life-cycle analyses will be key to successful reduction of India's contribution to global warming; and they can simultaneously improve the sustainability and self-sufficiency of India's energy supply.
General Information on LCA and International LCA Standards:
International Standards for LCA: ISO 14140
European Commission- Joint Research Centre, “LCA Tools, Services, and Data” (June 25, 2009).
Tan, R.R. Culaba, A.B., “Life-cycle Assessment of Conventional and Alternative Fuels for Road Vehicles” (Proc.,50th National Convention of the Philippine Society of Mechanical Engineers, Manila, Philippines. , 2002).:2.
Nuclear Power LCA:
Jan Willem Storm van Leeuwen, "Nuclear Power- The Energy Balance" Study commissioned by Green parties of European Parliament (2008)
Manfred Lenzen, “Life cycle energy and greenhouse gas emissions of nuclear energy: A review” Energy Conversion and Management 49 (2008): 2179.
"Greenhouse Gas Emissions of Nuclear Power Generation", World Nuclear Association website (February 2010).
"Nuclear Power in India," World Nuclear Association website (February 2010).
Jatropha Biofuel LCA:
Ajay Varadharajan, Venkateswaran W. S. and Prof. Rangan Banerjee, "Energy analysis of Biodiesel from Jatropha," World Renewable Energy Congress (2008).
Guido Reinhardt, "Screening Life Cycle Assessment of Jatropha Biodiesel" Report Commisioned by Daimler AG, Stuttgart (Institute for Energy and Environmental Research: Heidelberg, December 11, 2007)
Rangan Banerjee, "Analysis of Renewable Hydrogen," PowerPoint from Lecture at University of Nottingham (May 24, 2006).