Mortality and emissions

Fossil energy dominates the world's energy consumption but has the highest CO2 emissions and death rates. Nuclear and renewables are the safest energy sources with the lowest emissions but covers only a small share of global energy consumption.

The reputable website Our World in Data recently published an update of mortality and CO2-emissions for different energy sources. While the previous mortality studies were based on a Lancet article that looked at fossil fuels and nuclear power the new data also include renewables. At the same time, former figures from the Climate Panel have been updated with expected changes in the period up to 2050. The new data still require some adjustments to be as correct as possible, but the main conclusion is clear.

Nuclear power and renewables are very safe sources of energy

While few of us fear for our lives when we think about renewables, the situation is quite different when it comes to nuclear power. Our fear of disasters leads to a perception that nuclear is highly dangerous. Much of this is due to the Chernobyl accident, although the total death toll according to the WHO is limited to 4,000 (roughly what daily dies in traffic accidents globally), and where recent research suggests that the number could be even below 200. We also became frightened by the Fukushima accident, where radiation so far has cost only one human life, even though many hundreds lost their lives during the evacuation. However, this pales in relation to hydropower accidents that are nearly forty times deadlier than nuclear with nearly 180,000 deaths in the period 1950-2014, mainly related to a dam in China that burst in 1975.

While hydropower accidents are the deadliest and nuclear accidents the most expensive, wind power accounts for by far the most frequent accidents. It is, however, neither renewable energy nor nuclear that costs most lives, but fossil fuels. This is due to air pollution leading to premature death as a result of cardiovascular disease, respiratory diseases, cancer and more. According to Our World in Data, air pollution causes premature death of around 5 million people annually. In fact, more people die from air pollution from coal-fired power plants in China than have or will die from the Chernobyl accident.

To assess the safety of an energy source, mortality per terawatt hour (TWh) is listed. This is similar to the annual electricity consumption in a small European town with 27,000 residents. Using this to illustrate mortality, bituminous coal and lignite would on average cause 57 deaths each year, mainly from air pollution. Oil would cost 18 lives annually, while gas would lead to 3 annual deaths. The Lancet study relates only to Europe, and another study suggests nearly twice as high mortality globally for fossil fuels.

With nuclear, there would be no annual deaths among the inhabitants, only a maximum of one death every 14 years, including both the Chernobyl and mining accidents. Without Chernobyl, where the numbers are uncertain, there will be approximately one death each century. The shutdown of nuclear power in Germany is estimated to cost over a thousand German lives a year because renewables are not building up fast enough, and an article in Nature concludes that nuclear power so far has saved around two million lives globally by replacing fossil fuels.

When it comes to deaths related to accidents and air pollution, nuclear along with solar and wind are by far the safest energy sources we have. It makes relatively little sense to differentiate when at a level of a few deaths per 27,000 inhabitants every hundred years. However, it may be of interest to learn that in the period 1990-2013, wind power caused four times more fatalities per TWh than nuclear power. If deaths due to mining are included, the death rate for renewables is higher than for nuclear. Much of this is related to the larger material consumption for renewables, causing increased mining activity. Mortality rate is nonetheless very far from the levels caused by fossil fuels

Nuclear and renewables have the lowest emissions

Fossil fuels accounts for 95% of global CO2-emissions. Not surprisingly, coal emits most, followed by oil. Gas has much lower emissions, but still at levels much higher than that of renewable and nuclear energy. It is therefore not surprising that the Intergovernmental Panel on Climate Change promotes a reduction of fossil fuels combined with an acceleration of renewables, nuclear and carbon capture and storage as key instruments to become carbon neutral.

To calculate emissions, it makes sense to look at the entire life cycle of the power sources, which includes mining, transportation, construction, operations and shutdown. While coal emits 820 grams of CO2 equivalents per kWh, nuclear is expected to emit only 4 g/kWh in the period up to 2050. That's a huge difference. Wind is at the same level as nuclear, while solar emits two grams more. Hydropower has significant higher emissions, 97 g/kWh, which is mainly due to methane gas caused by degradation of organic matter. The new emission figures for nuclear and renewables are significantly lower than what the Intergovernmental Panel on Climate Change outlined in its main report. This is because the new figures relate not only to the current situation, but also to how the world is changing in terms of technology development and reduced indirect emissions.

It is fairly straightforward to conclude that the safest energy sources are also the ones with the lowest emissions – and quite disturbing to observe that they account for only 13% of the global energy consumption. And while few people doubt renewable energy's excellence in terms of safety and emissions, many have erroneous views about nuclear power, which is far safer and more climate-friendly than hydropower and biomass, and on par with both solar and wind.