Global solar photovoltaic industry is likely now a net energy producer, Stanford researchers find

[OKIsItJustMe]

11. Blah Blah Blah indeed…

http://pbadupws.nrc.gov/docs/ML1006/ML100601133.pdf

[font face=Serif][font size=5]Valuing the greenhouse gas emissions from nuclear power: A critical survey[/font]
[font size=4]Benjamin K. Sovacool[/font]

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Available online 2 June 2008
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[font size=3]5. Conclusion

The first conclusion is that the mean value of emissions over the course of the lifetime of a nuclear reactor (reported from qualified studies) is 66 g CO2e/kWh, due to reliance on existing fossil-fuel infrastructure for plant construction, decommissioning, and fuel processing along with the energy intensity of uranium mining and enrichment. Thus, nuclear energy is in no way ‘‘carbon free’’ or ‘‘emissions free,’’ even though it is much better (from purely a carbon-equivalent emissions standpoint) than coal, oil, and natural gas electricity generators, but worse than renewable and small scale distributed generators (see Table 8). For example, Gagnon et al. (2002) found that coal, oil, diesel, and natural gas generators emitted between 443 and 1050 g CO2e/kWh, far more than the 66 g CO2e/kWh attributed to the nuclear lifecycle. However, Pehnt (2006) conducted lifecycle analyses for 15 separate distributed generation and renewable energy technologies and found that all but one, solar photovoltaics (PV), emitted much less gCO2e/kWh than the mean reported for nuclear plants. In an analysis using updated data on solar PV, Fthenakis et al. (2008) found that current estimates on the greenhouse gas emissions for typical solar PV systems range from 29 to 35 g CO2e/kWh (based on insolation of 1700 kWh/m2/yr and a performance ratio of 0.8).

The second (and perhaps more obvious) conclusion is that lifecycle studies of greenhouse gas emissions associated with the nuclear fuel cycle need to become more accurate, transparent, accountable, and comprehensive. Thirty-nine percent of lifecycle studies reviewed were more than 10 years old. Nine percent, while cited in the literature, were inaccessible. Thirty-four percent did not explain their research methodology, relied completely on secondary sources, or were not explicit about the distribution of carbon-equivalent emissions over the different stages of the nuclear fuel cycle. All in all, this meant that 81% of studies had methodological shortcomings that justified excluding them from the assessment conducted here. No identifiable industry standard provides guidance for utilities and companies operating nuclear facilities concerning how to report their carbon-equivalent emissions. Regulators, utilities, and operators should consider developing formal standardization and reporting criteria for the greenhouse gas emissions associated with nuclear lifecycles similar to those that provide general guidance for environmental management and lifecycle assessment, such as ISO 14040 and 14044, but adapted exclusively to the nuclear industry.

Of the remaining 19% of studies that were relatively up to date, accessible, and methodologically explicit, they varied greatly in their comprehensiveness, some counting just construction and decommissioning as part of the fuel cycle, and others including mining, milling, enrichment, conversion, construction, operation, processing, waste storage, and decommissioning. Adding even more variation, studies differed in whether they assessed future emissions for a few individual reactors or past emissions for the global nuclear fleet; assumed existing technologies or those under development; and presumed whether the electricity needed for mining and enrichment came from fossil fuels, other nuclear plants, renewable energy technologies, or a combination thereof.

Furthermore, the specific reactors studied differ greatly themselves. Some utilize relatively high-quality uranium ore located close to the reactor site; others require the importation of low-quality ore from thousands of kilometers away. A nuclear plant in Canada may receive its fuel from open-pit uranium mines enriched at a gaseous diffusion facility, whereas a reactor in Egypt may receive its fuel from an underground mine enriched through centrifuge. A nuclear facility in France may operate with a load factor of 83% for 40 years on a closed fuel cycle relying on reprocessed fuel, whereas a light water reactor in the United States may operate with a load factor of 81% for 25 years on a once-through fuel cycle that generates significant amounts of spent nuclear fuel.

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