Questions about Life-cycle greenhouse gas emissions of energy sources
Short answers, pulled from the story.
What are the life-cycle greenhouse gas emissions of coal compared to nuclear power?
According to the IPCC 2014 harmonization, pulverized coal has a median life-cycle footprint of 820 grams of carbon dioxide equivalent per kilowatt hour, while nuclear power has a median of 12 grams per kilowatt hour. The UNECE 2021 analysis places the nuclear average even lower, at 5.1 grams per kilowatt hour, and a 2022 study by Electricite de France put the French nuclear fleet's 2019 footprint at less than 4 grams per kilowatt hour.
Which electricity source has the lowest life-cycle greenhouse gas emissions?
Wind onshore has the lowest median in the IPCC 2014 table at 11 grams of carbon dioxide equivalent per kilowatt hour, with nuclear and wind offshore both at 12 grams. The UNECE 2021 data show nuclear averaging 5.1 grams and cadmium telluride photovoltaic panels reaching as low as 12 grams per kilowatt hour.
Why does hydropower have such a wide range of greenhouse gas emissions?
Hydropower's median life-cycle emissions are 24 grams of carbon dioxide equivalent per kilowatt hour, but its maximum reaches 2,200 grams. Some reservoirs, especially in warmer regions, generate significant methane from organic matter decomposing under water, which can push individual power stations far above the typical range.
What did the IPCC 2014 report find about life-cycle emissions of energy sources?
The IPCC harmonized findings from hundreds of individual scientific papers and found coal to be by far the worst emitter, followed by natural gas. Solar, wind, and nuclear were all identified as low-carbon. Hydropower, biomass, geothermal, and ocean power can generally be low-carbon, but poor design or site-specific factors can produce higher emissions from individual plants.
How does carbon capture and storage affect the life-cycle emissions of coal power?
According to the UNECE 2021 analysis, pulverized coal without carbon capture and storage reaches 1,000 grams of carbon dioxide equivalent per kilowatt hour, while the same plant type with carbon capture drops to around 370 grams. Integrated gasification combined cycle coal with carbon capture falls to approximately 280 grams per kilowatt hour.
How long are wind, solar, and nuclear plants expected to last for life-cycle assessments?
Wind farms are generally estimated to last 30 years. Solar panels from the 2010s may have a similar lifespan, though the durability of newer materials like perovskite is not yet known. Some nuclear plants can operate for 80 years, while others may retire earlier for safety reasons; more than half the world's nuclear plants are expected to seek license extensions.