There is no single metric or trait that makes something ‘the best’ energy source. Rather a nuanced approach, one which reviews multiple metrics and evaluates how the various energy sources stack up across multiple categories, is most suitable. Five important factors to consider when comparing nuclear, wind, solar, and geothermal:

• Energy density
• Reliability
• Construction resources & impact
• Return on energy invested (EROI)
• Land use

Opinions will vary on which factors are most critical, and it is very possible changes in politics, economics, global trade, or technology will lead to improvements in one or more factors for certain energy sources. As things stand today, nuclear appears to be the ‘best’ clean energy source on the list. Winning out or tying for best in four out of five categories.

Note: Geothermal is not viable for electricity generation at scale, yet, so is left out of many of the comparisons. With advancements in the field it is possible geothermal becomes a large piece of our future energy mix, but this will take time and technological innovation.

Energy Density

To begin, we will rank each energy source’s energy density- the amount of energy that can be stored in a given volume or mass of the matter. Given this definition it makes sense that wind has the lowest energy density on this list. Solar and Geothermal come next, with a comparable energy density. Nuclear is by far the most dense energy source on this list- small amounts emit unbelievable amounts of energy.

Resources to Construct

For this topic, any resources used during construction or operation are fair game. Renewables have no input cost for their energy material, while nuclear plants require much simpler ingredients to construct than solar or wind. Table 1 shows that nuclear needs lots of concrete and steel, but not much else. On the other hand, solar and wind require even more of these things as well as aluminum, glass, and other. It is clearly more expensive to construct wind and solar than nuclear power plants. It is impossible to estimate the input cost of uranium to output 1TWh of electricity, which does cost money compared to the free fuel cost for wind and solar.

Materials requirements (excluding fuels) for electricity generation technologies: tonnes per TWh

Energy Return on Investment (EROI)

EROI attempts to measure how much energy a project will produce over its lifetime compared to the energy needed to build it. We need to first have an estimate of the cost to build a project, aka ‘Resources to Construct’. The other number we need is the total expected energy output of the system, which factors in any operational risks. Safe to say there are tons of bad EROI estimates out there- ones that don’t consider scenarios that aren’t the ideal one, or misrepresent costs. The best report I could find is by the WNA and aggregates multiple sources into a master table.

Assuming accuracy of the WNA reports, and that the cost of getting nuclear power plant fuel for 1TWh of production doesn’t offset the lower construction costs and higher energy output, nuclear is the winner.

Reliability

The biggest and most valid criticisms of solar and wind come down to reliability. These intermittent power sources are dependent on the sun shining and the wind blowing, something humans don’t control (yet). Nuclear and geothermal are both very reliable, the environment is highly controlled and fuel is omnipresent with proper planning. Either can be used for baseload energy, unlike solar and wind, though geothermal applications are currently limited.

Land Use

The opportunity cost of land use should not be overlooked when considering the best clean energy source. The motivation for clean energy is preserving the natural environment, thus the best clean energy would get the job done using the least amount of land. Nuclear wins this category by a mile, check out this graphic comparing wind, solar, and nuclear. Geothermal has a small footprint above ground, but covers a lot of real estate underground, which can occasionally have unintended consequences.

Conclusion

When considering the holistic picture, and acknowledging uncertainties, nuclear appears to be ‘the best’ clean energy source. The high energy density and reliability paired with low land use and resource costs are hard to beat. Solar and wind need something to provide a steady baseload, have more messy construction costs, and higher land use. This suggests these renewables might be best used case-by-case or to augment existing sources.

I like to think my bias for nuclear Power appeared after doing lots of research (this isn’t my first time considering the question), and not because I run a pro-nuclear power clothing brand. I decided to start this business after getting excited for the prospects of a nuclear renaissance to propel the clean energy transition. Share this article or consider shopping for a pro-nuclear shirt to support the movement.