Emissions from burning fossil fuels are toxic. The effect from a single power plant is small, but if you build a lot of fossil plants, it adds up. Air pollution kills people.
Climatologist James E. Hansen, who just this week retired as head of NASA's Goddard Institute for Space Science, has just co-authored a paper that has been accepted by the journal Environmental Science & Technology, in which he calculates that nuclear power has prevented 1.84 million deaths worldwide that would have occurred if nuclear power plants had been built as fossil-fueled power plants instead. That's actually a conservative figure, because it doesn't count a number of things, like the effects of CO2 on climate change.
Although this number isn't terribly surprising to those who study energy issues, it does point up a hugely under-reported aspect of energy policy: nuclear power is the safest way ever devised to generate electricity. Safer than wind. Safer than solar. And far, far safer than fossil fuels.
Using historical production data, we calculate that global nuclear power has prevented about 1.84 million air pollution-related deaths and 64 gigatonnes (Gt) CO2-equivalent greenhouse gas (GHG) emissions that would have resulted from fossil fuel burning. Based on global projection data that take into account the effects of Fukushima, we find that by midcentury, nuclear power could prevent an additional 420,000 to 7.04 million deaths and 80 to 240 GtCO2-eq emissions due to fossil fuels, depending on which fuel it replaces.
Hansen and co-author Pushker A. Kharecha estimated the prevented deaths by assuming that nuclear power plants that operate at less than 65% capacity factor would have been replaced by gas fired plants, and nuclear plants operated at more than 65% capacity factor would have been replaced by coal fired plants. (Capacity factor is essentially the amount of up-time for a plant). Since coal plants tend to have a high capacity factor, this assumed substitution makes sense. Under this assumption, 95% of nuclear plants would be replaced by coal.
Here's how various electric generation sources stack up on the health and safety issue. Data is from Markandya and Wilkinson 2007.
|Deaths per TWhr for electric generation
Data for renewables are harder to get, primarily because statistical experience is so limited. But one source, Next Big Future
|Deaths per TWhr
The hydro power world total is high because of the 1975 dam failure at Banqiao, China, which killed 171,000 people.
NBF's numbers for wind (0.16 deaths per TWhr) are from a wind industry source, and therefore should be considered optimistic. Obviously, building and maintaining a wind turbine involves a lot of climbing to very high (and windy) places. It also typically involves a lot of driving to get to those places.
But what about Chernobyl?
From Hansen's paper:
According to the latest assessment by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 43 deaths are conclusively attributable to radiation from Chernobyl as of 2006 (28 were plant staff/first responders and 15 were from the 6,000 diagnosed cases of thyroid cancer). UNSCEAR also states that reports of an increase in leukemia among recovery workers who received higher doses are inconclusive, although cataract development was clinically significant in that group; otherwise, for these workers as well as the general population, “there has been no persuasive evidence of any other health effect” attributable to radiation exposure.
Relevant statistics in the above quote are from UNSCEAR
Deaths from Chernobyl are included in both of the above estimates of the risk of nuclear power. A total of 64 people died at Chernobyl, both from immediate effects and the near-term aftermath, including those who died of non-radiation causes during the accident.
Many estimates of expected future cancer deaths from Chernobyl are hugely inflated, relying on collective dose computations that are scientifically unfounded. The risk of early death from small doses of radiation is still controversial, although data from Chernobyl may settle the case. The controversy is over a hypothesis called the "Linear No-Threshold" (LNT) model. At high doses, cancer death rates from radiation follow a linear relation with the amount of exposure: the more exposure, the greater the risk. It is not at all clear that the LNT model continues to correctly predict risk when doses are low; in fact, there has never been a study anywhere that demonstrates any human health risk from a radiation dose of 100 mSv or less.
After the accident, the Soviet government sent in 600,000 people to clean up the site, called liquidators. The reason for the large number was that they wanted to limit the exposure that any one person received. Most of the liquidators received radiation doses in the 100 to 200 mSv range, although some got as much as 250 mSv. (For comparison, typical background doses in the US are 2-3 mSv per year, though backgrounds are over 100 mSv per year in some parts of the world; symptoms of radiation sickness begin at about 1500 mSv; and a dose of 8000 mSv is always fatal.) If the LNT model is correct, we should be seeing thousands of excess cancer deaths among the Chernobyl liquidators by now. But the actual number of excess cancer deaths among the liquidators is statistically indistinguishable from zero.
The absence of evidence of large mortality from past nuclear accidents is consistent with recent findings that the “linear no-threshold” model used to derive the nuclear mortality factor in Table 1 (see ref 22) might not be valid for the relatively low radiation doses that the public was exposed to from nuclear power plant accidents.
But what about Fukushima?
From Hansen again:
Furthermore, no deaths have been conclusively attributed (in a scientifically valid manner) to radiation from the other two major accidents, i.e. Three Mile Island in March 1979, for which a 20-year comprehensive scientific health assessment was done; and the March 2011 Fukushima Daiichi accident.
The Tohoku earthquake and tsunami killed 16,000 people and caused the partial meltdown of three nuclear reactors at the Fukushima Daiichi power plant. Three other reactors at Fukushima Daiichi shut down normally, and four reactors at nearby Fukushima Daiini shut down normally.
The number of people killed by the subsequent radiation release was zero. The WHO has estimated that the most contaminated areas around Fukushima received doses of 10 to 50 mSv of radiation. That means that even if the area around Fukushima had not been evacuated, it is quite likely that not one person would have died from radiation.