Energy's deathprint is a rarely talked about measure of the number of deaths per unit of energy produced for different power sources. Here are the results from two studies on it.
|From page 168 Sustainable energy without the hot air|
As you can see coal, oil and biomass are particularly bad. This is because of small particles released while burning thing (i.e. ash or fly ash). These don't agree with people very much. Not only do these particles cause deaths, but they also cause other health problems. Some countries do a better job of filtering them out then others. With a bit of searching you can find info for a variety of similar studies. Here is another one. I thought this review of it was particularly insightful.
Global Warming is a serious issue. One study projects that...
Worldwide, upward of 20,000 air-pollution-related deaths per year per degree Celsius may be due to this greenhouse gas.That's rather extrema considering how long the temperature changes are projected to last. Here is a graph that shows the carbon footprint for various forms of electric generation.
|From Carbon footprint of electricity generation by Stephanie Baldwin|
From page 8 of Carbon footprint of electric generation. I suggest reading the whole PDF. It's not very long, and definitely worth it.
Ranges in each electricity generation technology are due to
- Differences between individual plants – some older and/or less efficient
- Different technologies – e.g. run-of-river vs. reservoir storage
- Different LCA input (boundary definition) parameters
- Different studies – some studies older, so had older data (2000 was cutoff date)
In regards to the difference for nuclear power. From page 18 of Carbon footprint of electric generation.
Issues:I would like to add to this that there are two important issues for understand nuclear power's carbon footprint. One is the method of fuel enrichment. Some have a bigger carbon footprint than others. The other is the type of reactor. Some reactors are able to use much more of the natural uranium mined then other which reduces their carbon footprint. I'm really hopping we will start making more breeder reactors so we can use all of it.
- Nuclear also has a very small carbon footprint
- Most CO 2 emitted during uranium mining (40% of life cycle CO2)
- Global uranium reserves – lower grades may cause footprint to rise in future
- 3 studies: AEA ( to 6.8g), Öko ( to 30-60g), Storm van Leeuwin ( 60 to 120g)
Radioisotopes Released into the Environment
I'll just give a brief description for coal, natural gas and nuclear power that will hopefully give you some idea about the radioisotopes (i.e. the stuff that produces radiation) they release into the environment. For your information sometimes when people in the news talk about radiation they are talking about radioisotopes and sometimes they are talking about ionizing radiation. If you’re not familiar with these concepts you may wish to read my post Some Basic Information Useful for Understanding Nuclear Power Safety.
Radioisotopes and fossil fuels
There are radioisotopes mixed into almost everything. This includes fossil fuels. When you burn the fossil fuels these radioisotopes become more concentrated (in the ash) then they are in the natural environment. This can result in people having more radiation exposure then they would otherwise.
Radioisotopes Released by Coal
The main radiation release from coal is in the form of fly ash. In order to give you some idea about what this entails let me start out with a few quotes.
From the USGS - Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and Environmental Significance
Coal is largely composed of organic matter, but it is the inorganic matter in coal—minerals and trace elements— that have been cited as possible causes of health, environmental, and technological problems associated with the use of coal. Some trace elements in coal are naturally radioactive. These radioactive elements include uranium (U), thorium (Th), and their numerous decay products, including radium (Ra) and radon (Rn). Although these elements are less chemically toxic than other coal constituents such as arsenic, selenium, or mercury, questions have been raised concerning possible risk from radiation. In order to accurately address these questions and to predict the mobility of radioactive elements during the coal fuel-cycle, it is important to determine the concentration, distribution, and form of radioactive elements in coal and fly ash.
10-30 ppm uranium in fly ash
10-30 ppm thorium in fly ash
From the EPA - Coal Fly Ash, Bottom Ash and Boiler Slag
In 2012, 59 percent of the coal consumed by electric utilities and independent power producers in the United States resulted in the generation of about 68 million tons of fly ash, bottom ash and boiler slag. An additional 42 million tons of other residuals were generated from flue gas desulfurization and fluidized bed combustion.
Fly ash is carried up with hot flue gases and trapped by stack filters. It is the largest of the coal combustion residuals (about half) by weight.
Stack filtration devices, such as electrostatic precipitators, baghouses and scrubbers are routinely used to reduce the emission of fly ash. They are about 99 percent effective. Only about one percent is released into the air.
Emphasis AddedNow lets do a little math with these numbers.
68,000,000 tons * 50% * 1% = 340,000 tons
So, in 2012, 59 percent of the coal consumed by electric utilities resulted in 340,000 tons of fly ash being released into the air.
((340,000 tons * 10ppm) / 1,000,000) * 2,000 lb./tons = 6,800 pounds*
((340,000 tons * 30 ppm) / 1,000,000) * 2,000 lb./ton = 20,400 pounds*
*assuming tons is short tons and ppm is a mass fraction.
Extrapolating for the other 41% we get...
6,800 lb / .59 ≃ 12,000 pounds
20,400 lb / .59 ≃ 35,000 pounds
So in 2012, we had roughly between 12,000 and 35,000 pounds of radioactive uranium and roughly between 12,000 and 35,000 pounds of radioactive Thorium being released into the air by electric utilities resulted. If it wasn’t for the consumption of coal in production electricity this Thorium and Uranium would have remained under ground where it couldn’t possibly hurt anyone. Instead it was released into the air in the form of small particles which often end up the the lungs of people and animals.
Now lets talk about Radon
Radon is a colourless odorless gas that is responsible for a large part of people's yearly radiation dose from natural sources. So let try and figure out how much radon is release from a years worth of coal.
In the Us 858,000,000 Short tons of coal a burnt each year. There is around 1 to 3 parts per million uranium in Us coal. So there is between 858 and 2574 tons of uranium in a years worth of coal.
Assuming that the amount of uranium has stayed basically constant over the years, that none of the decay chain products have left the coal and that the decay products move through the chain at roughly the same speed (all fairly safe assumption to make), then the Radon produced each year by the coal equals the uranium 238 that decays each year.
(9,600 Gd/sec X 3.15569e7 sec. / 6.02214129×1023) X 222 ≃ .11Grams
decays a sec in a year 1 Mole mass Rn-222
(29,000 Gd/sec X 3.15569e7 sec. / 6.02214129×1023 ) X 222 ≃ .23 Grams
decays a sec in a year 1 Mole mass Rn-222
So a years worth of coal in America creates around .11 to .23 grams or 590 to 1,800 TBq of radioactive gas. Of course this says nothing about where it's released, and it also says nothing about the addition Rn-222 that it will continue to released from the coal ash ponds for years to come.
So should we all panic and run for the hills?
According to the first source.
The radiation hazard from airborne emissions of coal-fired power plants was evaluated in a series of studies conducted from 1975–1985. These studies concluded that the maximum radiation dose to an individual living within 1 km of a modern power plant is equivalent to a minor, perhaps 1 to 5 percent.From a more recent study.
McBride and his co-authors estimated that individuals living near coal-fired installations are exposed to a maximum of 1.9 millirems of fly ash radiation yearly. To put these numbers in perspective, the average person encounters 360 millirems of annual "background radiation" from natural and man-made sources, including substances in Earth's crust, cosmic rays, residue from nuclear tests and smoke detectors.
There are a lot of radioisotopes in the coal all the Us burns each year, but not all of it ever reaches the public (Most fly ash is captured and stored), Radon-222 has a half life of only 3.8 days so it's unlikely to get to far plus it will quickly be diluted in as it spreads out from the plant and also the radio isotopes in coal aren't that concentrated to begin with although burning it makes them somewhat more so.
Radioisotopes Released by Natural Gas
I know what you're thinking. They couldn't possible pump radioactive gas into our homes right? Well...
It has been known for over 40 years that radon, a radioactive gas, is present in natural gas. Reports by R.H. Johnson 7 and C.V. Gogolak 8 calculate the health effects due to burning natural gas in kitchen stoves and space heaters. In an US Environmental Protection Agency report, Raymond Johnson calculate s the number of lung cancer deaths due to inhalation of radon in homes throughout the U.S. as 95 due to radon concentrations in the pipeline of 37 pCi/L.
Yikes. By the way that quote came from this study that estimates the problem is much worse in New York because of gas from the Marcellus shale. It estimates that the gas from the Marcellus shale raises the death toll by 1,182 to 30,448 a year. That is a significant number. Here is a blog post contesting that study. Unfortunately neither the study or the blog post that contests it have actual measurements from the Marcellus shale well heads. Something you would think someone would want to take.
While this all sounds scary it should be noted that there is controversy in regards to the effect of low level radiation.
Radioisotopes Released by Nuclear Power
Here is an awesome graphic that explains it all.
There isn't one really. I hope learned something and you enjoyed it.