I think that this question cannot be answered simply and briefly and I will rather try to explain why it cannot be answered. Perhaps it will then be clearer why the answer is fundamentally impossible.

When producing electricity, we have to consider many completely different criteria, and only then can we address the specific fuel.

The first criterion is the environmental impact — whether and how the electricity production will affect the environment. The second is the availability of fuel in the long term and again the impact of its extraction on the environment. Another factor is the availability of the energy produced in this way — do we have it available all day or only under certain conditions? The availability of energy is also linked to the speed of “turning on” the source — can we use the source immediately if needed, or will we have to wait? And if so, how long? Another significant factor is the area that the given type of power plant occupies per unit of energy produced. We must also take into account the economic aspect — the costs of building and operating the power plant itself. Last but not least, it is also important to consider the operational demands — both the number of people required to operate the source and the qualifications needed.

And all the aforementioned parameters must be put into context with the existing sources in the given region and the transmission system, so that the end customer can be assured that they will always be able to connect their devices to the electrical grid and the system will function.

I will provide a few examples to illustrate the reasons for constructing different types of power plants.

Nuclear power plants have the advantage of occupying the smallest area for the amount of energy produced and the fuel is relatively easy to transport (one 5 g uranium pellet replaces 800 kg of coal). That is why nuclear power plants are widespread in Japan. Apart from scheduled outages, the power plant operates 24/7. However, nuclear power plants are demanding in terms of construction and operation and we have not resolved the handling of spent fuel.

Coal-fired power plants have the advantage of fuel availability and cost, as well as relatively low construction and operation complexity. They also operate in a 24/7 mode and require a small area per unit of energy produced. However, they have ecological impacts on both the mining and production landscapes. The extraction of coal itself is responsible for the most deaths. Moreover, coal reserves are not inexhaustible.

Instead of burning coal, we can burn biomass (animal and plant waste); technologically, it is a bit more complicated, and due to its lower heating value, the power plant will take up more space. We always have biomass available, and burning it also helps us get rid of waste. But burning anything, in principle, generates gases that burden the environment.

We can also burn natural gas — the environmental impact is smaller than that of coal-fired power plants and gas power plants can be turned on quickly if needed. However, the availability of fuel is a complication (as was demonstrated during the heating crisis caused by the war in Ukraine).

The least demanding and environmentally friendly (aside from production) to operate are wind and photovoltaic power plants but the acquisition costs (per unit of energy produced) are relatively high. These sources occupy the largest area per unit of energy produced and they only function under favourable conditions.

Hydroelectric power plants have a significant advantage in that (again, aside from construction) they do not impact greenhouse gas production. However, they occupy a large area per unit of energy produced and can only operate for a limited time. But even so, they have a crucial place in the energy sector. They can be turned on very quickly and thus correct short-term fluctuations in network consumption.

I hope it is now clear that any comparison of sources of electrical energy is fundamentally impossible without defining specific requirements.

In conclusion, I must clarify that although I wrote about the production of electrical energy, we do not produce energy. We merely convert it from one form to another.