Nuke vs. Solar: The Carbon Calculus
NEWS: How life-cycle emissions stack up for various fuels—plus, the nuclear breakdown
April 28, 2008
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A given energy source doesn't simply pollute—or not—as it's converted into electricity. There's also mining, plant construction, transportation, and other factors to consider. Looking at the big picture is the point of life-cycle numbers like these, expressed in grams of carbon dioxide equivalent per kilowatt-hour of electricity created.
Lifetime carbon emissions by source (g/kwh)
Coal: 1,006
Oil: 742
Natural gas: 466
Solar: 17 to 39
Nuclear: 16 to 55
Hydro: 18
Geothermal: 15
Wind: 14
The U.S. Nuclear Breakdown
Mining and milling: 1.7 (g/kwh)
Includes unearthing and transportation of uranium to refining and enrichment facilities
Enrichment: 13
By far the most carbon-intensive part of the fuel cycle, enrichment is needed to concentrate uranium isotope U-235 from its natural level of 0.7 percent to the 4 percent required for reactor fuel. The United States uses a gaseous-diffusion enrichment method that gobbles 40 times more energy than the gas-centrifuge process used in Europe, but a planned switch to centrifuge enrichment will shrink nuclear's domestic carbon footprint significantly. Once enriched, the uranium is shaped into small pellets and inserted into fuel rods.
Construction: 1.5
Building a nuclear power plant takes time, hundreds of thousands of metric tons of steel and concrete, and billions of dollars. It also requires lots of diesel trucks and industrial machinery, which translates into greenhouse gas emissions. Fortunately, a nuclear plant should last 40 years or more, which helps reduce its overall emissions per kilowatt-hour.
Plant operation: 3.9
Fission doesn't produce CO2, but replacement of spent fuel rods, plant heating, and other routine procedures do put a small load on the environment.
Temporary storage: ~1
Nuclear plants must store their own waste on-site or at an approved temporary site until Yucca Mountain is allowed to receive it. Transporting and storing the waste creates its own minor carbon footprint.
Nuclear total: ~21 g/kwh
If the industry switches entirely to centrifuge enrichment, the total will fall to around 12 g/kwh.
http://www.energynews.co.za/web_mai n/article.php?story=20080311120936953
I appreciate you asking for a source... that is always my first question, too.
Here is a source I found. The IAEA is a United Nations sponsored group that deals with all matters nuclear. Their researchers came up with the following which mirrors the info above somewhat. I have over many years reviewed IAEA's work and found it to be fairly objective.
http://www.iaea.org/Publications/Ma gazines/Bulletin/Bull422/article4.pdf
Dave: You posted this reference in another MJ forum. The link does not work and I asked that you look at this and re-post.
For others, energynews.com is South African "environmental" website that posts energy related articles/opinions.
Thanks much,
Bruce
SolarEnurgy.net
I posted the IAEA reference. Ike asked the same question you are from the opinion piece...where did the author get the numbers.
The major reason for nuclear coming out so well is the tremendous amount of electricity generated for the amount of GHGs created throughout the cycle. Likewise, solar and other options do poorly in this comparison due to the limited amount of electricity generated.
Thanks for the reply. So who is the author of this piece and where is the source for the "Nuclear Breakdown"?
It would be helpful to know. Thanks.