NREL develops more precise look at cradle-to-grave greenhouse gas emissions for energy technologies

[phantom power]

The method – a harmonization of widely variant estimates of greenhouse gas emissions by the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) – is being heralded as an important step forward in life-cycle assessments that paints a clearer picture of the environmental penalties and benefits of different technologies.

NREL analysts looked at more than 2,000 studies across several energy technologies, applied quality controls and greatly narrowed the range of estimates for greenhouse-gas emissions.

The harmonization found that cradle-to-grave greenhouse-gas emissions from solar photovoltaics are about 5 percent of those from coal; that wind and solar are about equal in emissions; and that nuclear energy is on a par with renewable energy.

And the analysis succeeded in narrowing the huge range of estimates – in some cases by 80 percent to 90 percent – to a robust median, improving precision, and giving stakeholders a much clearer look at the likely environmental impacts of various projects.

http://phys.org/news/2012-05-nrel-precise-cradle-to-grave-greenhouse-gas.html

[kristopher]

1. Journal articles available free here

http://onlinelibrary.wiley.com/doi/10.1111/jiec.2012.16.issue-s1/issuetoc

[NickB79]

2. "Nuclear energy is on a par with renewable energy"

I got plenty for everyone!

[kristopher]

3. That is largely undisputed.

The dispute involves what happens if we turn to nuclear as the primary global energy source and is caused by evaluations of the amount of CO2 emissions resulting from declining quality of uranium ore. The NREL group considered this and have a brief discussion of their choice of assumptions. I'll wait for Storm van Leeuwen's response before forming an opinion of the NREL results.

Future Uranium Ore Grade Scenario Projections
Many factors that influence nuclear life cycle GHG emissions are expected to improve over time, lowering GHG emissions. For example, the increased use of multipurpose mines reduces the energy required to extract uranium, and the gradual switch to centrifuge uranium enrichment reduces the energy required for this process compared to diffusion enrichment. On the other hand, if the global uranium market-average ore grade decreases over time, life cycle GHG emissions could increase for the average nuclear power plant due to higher energy demand for uranium recovery. Emissions from mining and milling can contribute to a significant portion of life cycle GHG emissions; for example, Dones and colleagues (2007a) estimate approximately 30%. Uranium is a nonrenewable resource and global rates of recovery are highest for the higher-quality ore grades, even though the majority of global recoverable resource consists of lower ore grades (ABARE 2004, IAEA 2008). The potential impact of decreasing uranium ore grades creates a major difference between nuclear and renewable technologies for future GHG mitigation potential6 (Storm van Leeuwen 2007). Here we use a scenario analysis framework similar to Storm van Leeuwen's (2007), but without the influence of the AEI method, with more recent data, and with a more global focus. The present analysis is intended to explore the boundary of the potential impact of decreasing ore grade on life cycle GHG emissions.

Life Cycle Greenhouse Gas Emissions of Nuclear Electricity Generation

Systematic Review and Harmonization
Ethan S. Warner, Garvin A. Heath

http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/full