Nuclear and Hydroelectric power producers estimate lower emissions of CO2 than other analysts give. They have only limited explanations, which are given below.
The Swedish Nuclear power producer, Vattenfall, says they are bound by confidentiality agreements. They cite their full study at http://www.environdec.com/reg/021/dokument/EPDforsmark2007.pdf
An email on 23 April 2009 said:
Generally, all emission factors for background processes (e.g. production of concrete, steel or chemicals) as well as emission factors for transport services were taken from the ecoinvent database (http://ecoinvent.org/). The database provides very detailed documentation for all modeled processes and also includes information on e.g. CO2 emissions from concrete production.
CO2List.org asked the following questions, and NOK gave the indented answers in an email on 4 May, 2009:
p.18 shows grams of greenhouse gases for 10 categories. Is there any more detail about how these 10 numbers were calculated? For example what were the fuel and production at the ISL mine or the other upstream processes? Or the concrete, steel or money used in construction, with factors for greenhouse gases? Does the concrete include just heat, or also the CO2 released from calcining CaCO3 => CaO + CO2 ?
The Swedish Hydroelectric producer, Vattenfall, uses data at odds with other researchers, to report low emissions, of 3.1 g CO2/kWh (0.007 pounds/kWh) from flooding the land. Their full study is at http://www.environdec.com/reg/088/dokument/08_waterEPD.pdf.
They give the explanation indented below. The explanation cites Adams of Oak Ridge National Lab for a figure of 10,000 tonnes of Carbon per square kilometer of Boreal soil (100 tonnes/hectare). Adams' data are at http://www.esd.ornl.gov/projects/qen/carbon12.html and actually show 129 tonnes of Carbon per hectare of Boreal soil, not 100. Later figures from Oak Ridge (Houghton & Hackler 2001) say 206 tonnes per hectare in Boreal soil. Vattenfall assumes only half of their low figure of 100 tonnes does decay.
Furthermore the Carbon in surface vegetation removed before inundation also needs to be counted, since it decays or burns (a small part would have been made into products which in turn are disposed of during the 100 year time frame Vattenfall uses).
Vattenfall also says their reservoirs absorb CO2, through the action of algae, though a variety of researchers have measured gas exchanged at reservoir surfaces, and find CO2 being generated, not absorbed.
All these figures and sources are compared in the spreadsheet. Vattenfall's explanation follows, from an email on 15 April, 2009:
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