"The race against climate change is both a marathon and a sprint," declares a new report from the US National Academies of Science. While we need to start decarbonizing immediately with the tech we have now—the sprint—the process will go on for decades, during which technology that's still in development could potentially play a critical role.

The technology at issue in the report is a new generation of nuclear reactors based on different technology; they're smaller and easier to build, and they could potentially use different coolants. The next generation of designs is working to avoid the delays and cost overruns that are crippling attempts to build additional reactors both here and overseas. But their performance in the real world will remain an unknown until next decade at the earliest, placing them squarely in the "marathon" portion of the race.

The new report focuses on what the US should do to ensure that the new generation of designs has a chance to be evaluated on its merits.

The next generation

Most of the next generation of nuclear power designs fall into the category of what are termed small modular reactors (SMRs). These designs have two emphases: They are modular and could potentially be mass-produced, and they focus on inherent safety. Combined, these factors will theoretically allow for rapid and cheap production of reactors and a far lower footprint for the supporting power plant where the reactors are installed.

Many of them generate power by boiling water. But some use more unusual coolants, such as gas, molten salt, or liquid sodium. Every one of them, however, shares a critical feature: They haven't been built. All the expectations we might have about their costs, electricity production, and so forth are estimates. The only approved small modular design will first be incorporated into a power plant at the end of the decade—if everything goes well. Some other companies plan to be ready to go into production sooner, but their designs aren't yet approved.

While these designs are unlikely to compete on cost with renewables, they have a number of potential uses once the low-hanging fruit of decarbonization has been picked. These include helping with managing the intermittency of renewables, providing heat for hard-to-decarbonize industrial processes, and even desalination or the production of hydrogen (either for direct use or for the production of synthetic fuels).

The report acknowledges that the potential utility of next-generation designs is completely up in the air, noting that it will depend on "the evolution of energy policy, comparative economics with other energy technologies, the challenge of building plants on budget and on schedule, future energy demand and the structure of the grid, societal preferences, and the prospect of using nuclear energy for purposes beyond electricity generation."

But the report's authors write that there's value in maintaining next-generation nuclear as an option since we don't know how any of those factors will evolve over the coming decades.

For everything to work out, there's an equally long list of things that will need to be accomplished. These include "completing demonstrations of new reactor technologies, verifying new business cases (e.g., non-electric applications), showing improved cost metrics that are competitive with other low-carbon power generation technologies, improving construction and project management compared to current LWR builds, obtaining timely regulatory approval, gaining societal acceptance in host communities, and responding to security and safeguard obligations," the report says.

The focus of the report is on how we can create a favorable environment for those things to happen.