Can Nuclear Energy be considered green?

The debate whether nuclear energy can be considered a green energy has been ongoing for decades, and both sides – those who agree and those that don’t – seem to be entrenched in their positions. However, the topic of nuclear energy has re-surged once again. The reason for this is the current energy crisis taking place in the EU and the urgent need to find alternative energy sources and lower the European energy market’s dependency on Russian supplies.

Some believe that it could represent a valid solution to “carry” the EU towards a more sustainable and independent energetic future, while others see nuclear energy as a serious step backward in the effort of greening Europe’s energy supply. With that in mind, let us delve on this matter. 

Arguments against 

One of the most well known environmental NGOs and simultaneously one of the main actors against the use of nuclear energy, Greenpeace, summarises the reasons why it would not be “the way to a green and peaceful world” in six main points:  first, shifting to nuclear energy would not lower emissions enough; quoting  data from the World Nuclear Association and the OECD Nuclear Energy Agency, the organisation argues that even if the world doubled its nuclear power capacity, it would still only account for a 4% reduction of greenhouse gas emissions. Secondly, it advocates that facilities are too vulnerable against potential terrorist attacks, natural disasters and war. Third,  because they argue nuclear energy is too expensive: according to a report mentioned by the environmental NGO, the production of nuclear energy is more than twice as costly per megawatt-hour than solar or wind energy. Next, they believe that this alternative is  too slow: the time required to build a nuclear power plant (NPP) is too long for it to produce appreciable effects in reducing emissions. Furthermore, they assert that it produces great quantities of toxic waste for which there is no permanent solution. And lastly, the technology is not advancing as quickly as it promised: Greenpeace argues that reactors currently in operation are outdated, as well as affirming that there have not been significant scientific advances in recent years and that nuclear fusion only seems like a distant dream.

Arguments in favour 

According to its supporters, nuclear energy is clean and  produces pollution-free power and no greenhouse emissions. An article published by the Breakthrough Institute in Oakland, California, draws a connection between the five fastest-decarbonising countries and the fact that they all employ nuclear energy, leading many of its advocates to consider it as responsible for the fastest decarbonisation effort ever. After the construction costs for the NPP, which can be quite expensive, supporters assert that the production itself is cheap and does not have the price fluctuations that coal and gas have. It is considered as more reliable than other sources, including green ones such as wind and solar, because it does not depend on variable weather conditions to produce energy. Moreover, it requires less maintenance and longer time can pass before the power plant needs to refuel. For these reasons, a nuclear energy plant can function at maximum power 92% of the time during the year, according to data reported by the US Office of Nuclear Energy.

Despite the fact that nuclear waste is highly radioactive, 90% of the waste resulting from nuclear energy production can be recycled, and supporters affirm that it still is a more easily manageable problem than climate change. In addition to production waste, uranium, the fuel used in the reactor, can also be recycled. Supporters quote data showing that nuclear waste remains very much less harmful to our health than the toxic chemical waste produced by the coal and oil industry. The US Office of Nuclear Energy states that this type of energy would be even preferable to most renewable energy sources (RES), as they claim it has by far the highest production capacity and reliability. Lastly, among its supporters, there is a shared belief that technological progress will lead to the achievement of nuclear fusion, which would provide practically infinite energy.

What does the Science say?

As presented above, supporters and opponents have completely opposite views. But what’s interesting to highlight is that both sides take the very same elements and present them under incompatible lights (expensive vs cheap, little impact vs the best solution, and so on). So, understandably, there is some confusion about who is right, and the media treatment of the subject surely does not help to clear things out. As such, what does Science have to say about this?

Andrea Bersano, a research fellow at Politecnico di Torino, Italy, together with his colleagues confirms the fact that nuclear has very low emissions, considering the whole life cycle from the construction to the operation of the NPP. In fact, the “smoke” that comes out of the cooling towers is actually just water vapour resulting from the heating up of water within the reactor. Studies cited by the authors find that a larger consumption of nuclear energy would decrease the CO2 emissions in the world, while the link between RES and emission reduction does not seem to be as strong. In terms of CO2 emissions (kg of CO2 per GWh) caused in the whole life-cycle of various energy sources, nuclear energy emits 2.5 times less than wind, 9.3 times less than photovoltaic and 42 times less than coal. In terms of the amount of material necessary to build production facilities, nuclear ranks before RES again. Moreover, the energy density of nuclear power (that is, “the quantity of energy per unit volume stored in a given material or object, or present in a given space”) is vertiginously higher than that of fossil fuels thanks to nuclear reactions instead of chemical reactions. We’re talking over 88 thousand times higher than crude oil! For RES, the authors consider as energy density the amount of land space required: for equal amounts of energy produced, solar requires 20 to 50 km², wind farms 50-150km² and nuclear between 1 and 4km².  

Another argument brought forward by nuclear energy advocates is supported by scientific data: this type of energy is indeed more reliable, in fact nuclear energy is identified in the study by Bersano and colleagues as “the only carbon-free option to substitute fossil fuels as backup for renewables”, because it can produce continuously with no interruptions and no dependence on external factors. Some countries have adopted renewable sources as their main sources, but the paper highlights that these are often sparsely populated countries which benefit from particular natural advantages in the production of solar or wind energy, but that this solution could not be effectively applied to industrialised countries. 

When imagining a future scenario in which RES cover for the main load of energetic needs, the backup source is always natural gas, but the authors argue that nuclear would be a much more valid alternative. From the point of view of fuel availability and stability of the supply, nuclear energy proves itself as a much more preferable solution than fossil fuels in terms of estimated remaining years of consumption of uranium. Regarding safety, statistics show that nuclear energy is not only safe, but it “holds the lowest severe accident frequency and death-to-unit energy ratio in the energy field”, with the probability of dying from an accident in a nuclear power plant which is comparable to that of being hit by a meteorite. After all, nuclear energy is the only energy source to have a dedicated control body, the International Atomic Energy Agency (IAEA), a UN subsidiary intergovernmental organisation with over 160 member states, devoted, among other things, to the control of safety standards of nuclear plants all over the world. Politecnico researchers further explain that, despite the elevated cost of the construction of a NPP, it would drastically cut the expenditure for electricity imports and fossil fuels purchase, along with the reduction of indirect costs generated in the healthcare system by air pollution. To conclude its advantages, nuclear energy production generates big quantities of excess thermal energy as a by-product, which can be used to heat households in large cities.

On the other hand, the authors report that the production of nuclear energy is indeed quite costly, especially considering the capital costs of building a NPP, yet while nuclear is not competitive with fossil fuels, which have considerably the lowest overall costs (i.e. capital costs plus operating costs in $/kW), it is comparable with the cost of RES. 

Furthermore, another crucial issue in the debate around nuclear energy lies in the waste it produces as well as in its disposal process. Currently in Europe, nuclear waste is stored in temporary deposits, with the purpose of being put later into permanent ones, whose  construction seems to be continuously delayed. So far, Finland is the only EU member that is building a permanent repository, while France and Sweden have only determined the location for the future deposit, with the question of waste disposal remaining  open. 

However, highly radioactive waste from nuclear energy production amounts to just three cubic metres per year, assuming the fuel used is recycled, stored in shielded containers and placed in (temporary) controlled deposits. Additionally, it is important to underline that other sectors of most countries’ economies produce radioactive waste in much higher quantities than NPPs such as industry, research and healthcare, although the general public does not seem to be as concerned by the latter. In fact, the study observes that a big obstacle to nuclear energy is represented by the public non-acceptance and fear of this technology, understandably caused by the Chernobyl (1986) and Fukushima (2011) accidents.

What about the risk of another disaster?

Speaking of Chernobyl, how likely is it that a disaster like the one occurred in 1986 in Ukraine will happen again? The short answer is: not much. To understand this, we have to have a clear image of what happened in 1986. The accident, which caused 54 direct victims and an estimated 4000 deaths caused by prolonged exposure to radiation, happened at night, during a test at low-power, with the safety protocol voluntarily ignored and the emergency safety systems manually shut off. Most importantly, the Chernobyl NPP did not have a containment structure around the core: a concrete structure built around the reactor’s core to contain potential radioactive releases, which is now compulsory in all NPPs. In the years prior to the accident, there had been several reports of malfunctions, but the Soviet Security Agency (KGB) chose to ignore the warnings and swiped them under the carpet.

Regarding the Fukushima accident, what happened was once again extraordinary and hardly replicable. The Japanese power plant was flooded with seawater, and the generator that powered the cooling system was made non-operational by the flood, causing the fusion of three still-warm cores, with subsequent release of nuclear waste in the atmosphere, which fortunately caused no casualties. The flooding was caused by a fourteen-metre tsunami, which went over the nine-metre protection wall, and the tsunami was caused by the fourth strongest earthquake ever registered in history, which is not a common event.

Going back to Ukraine, but in present days, numerous concerns have rightly been raised around the Zaporizhzhya NPP, which is threatened by the ongoing war. A team of IAEA experts is currently on site, monitoring the situation despite the conflict, and they report that the situation is still risky, because of the frequent cuts in electricity supply to secure the reactors. In the latest reports available at the time of writing on the situation in Zaporizhzhya, the control body’s Director General, Rafael Grossi, affirmed that the Zaporizhzhya NPP is in shutdown mode and the risk is therefore lower, but it is is still necessary to make every effort to ensure that the safety functions are maintained. Mr. Grossi described the situation as “precarious, fragile and potentially dangerous”, but he also mentioned ongoing progress to establish a nuclear safety and security protection zone around the NPP.

However, even considering past accidents, nuclear disasters remain very rare. In fact, there has been only a very small number of incidents since the beginning of the use of this technology in the late 1950s, in any case lower than the many fatal, but often overlooked, accidents in other energy sources.

This article was first published in the issue 37 of the magazine