Tim Panton (@steely_glint) asks: “Will nuclear energy replace fossil fuels? If so, will it be fission or fusion?”This is one of those questions that is hard to answer accurately without sounding like you are trying to fudge it. Because the answers are ‘yes, but only some’ and ‘both, but not at the same time’. And also, ‘it depends what application you’re talking about’, and ‘over what time frame?’

One of many

The first challenge in answering this question comes back to one of the five major trends I track that I see popping up in every domain I examine: choice. We live in an age of low-friction innovation, where building novel solutions to problems is easier than it ever has been. That does not mean it is easy, but it does mean that the turnover of new technologies is faster, and that the variety of technological solutions is wider.The adoption of these technologies is also easier and cheaper. With lower barriers to entry, people can afford to experiment more. And with lower innovation and production costs, suppliers can afford to support smaller niches.The result is that there is rarely one answer to any problem. It is impossible to say that nuclear will replace fossil fuels because LOTS of things will replace fossil fuels. Indeed, they already are. Check out this chart from the IEA’s 2019 World Energy Outlook report: https://www.iea.org/data-and-statistics/charts/installed-power-generation-capacity-by-source-in-the-stated-policies-scenario-2000-2040This is specifically for the power generation market – electricity, in other words. What it shows is that coal consumption has flattened, and oil is down, while gas continues to grow. Meanwhile, solar and wind are on incredible growth trajectories. Hydro and other renewables are also growing. In the IEA’s projections, nuclear is fairly flat. This is all over a 20-year time frame with projected global energy consumption continuing to rise.

Fission flat

These projections seem plausible to me. We might hope to see a faster decline in gas and coal offset by even more dramatic shifts to solar and battery storage. This is possible with large infrastructure investment in those countries with highly centralised grids. Given the noises about economic stimulus investment in the UK and elsewhere, we might just see some of this. But it is hard to see the nuclear picture being anything other than (largely) flat.This is not because there will not be new nuclear. But lots of reactors in places like the UK and France are ageing and well beyond their original design life. So even large-scale development will only hit replacement levels. There is some hope for smaller scale nuclear systems that might fit well into a more distributed grid infrastructure as a back up to primarily renewable generation, or that could be clustered to replace coal or ageing nuclear plants. Certainly, lots of investors, including governments, think this idea has strong prospects. But it is hard to see it growing at a rate that makes it a serious candidate for replacing the majority of fossil fuel consumption, even just for energy generation.

Commercial fusion?

Meanwhile, fusion research continues to make slow progress. It is hard to see it hitting commercialisation at any real scale in the 20-year IEA time frame. Even if the model is proven, it is unlikely anyone in the west would be able to build out a reactor within another decade. China is a different matter and there, practical fusion power might be a valuable alternative to the country’s enormous reliance on coal. But still, it is hard to see it making a serious impact in the next twenty years.

Renewables

Meanwhile, solar, wind, hydro and tidal power advance apace. As does the storage technology to offset their intermittent feed. Done at very large scale, these projects require very large investment – the sort that takes years to assemble or that has to be underwritten by governments. But done at smaller scale, they can be rolled out relatively quickly and cheaply. This feels like the best bet for a lot of fossil fuel replacement.Roughly two thirds of grid energy consumption in the UK is in residential and commercial venues, where small scale renewables and storage might present an opportunity to shift away from grid power for at least a proportion of usage. The shift to electric vehicles means that these sources might also power a lot of our transport. Only in large scale industry like steel manufacturing does small scale renewables and storage feel less practical – though I would be delighted to be proven wrong on this. Perhaps here is the opportunity for small scale nuclear? Single or clustered plants could be used to provide consistent, clean(er) energy to major consumers and the surround areas.

Looking beyond

In the longer term, fission feels like a dead technology. It is cleaner than coal but still leaves a lot of radioactive mess behind that we don’t have a good solution for. I do believe we will one day crack the fusion challenge, allowing us to generate a lot of energy in a small space. But remember: however sophisticated the heat source, nuclear fusion would still be used to make steam to spin a turbine. This is the same way we have been generating power for 140 years or so. Even the Romans were using steam to make stuff spin. It feels a little old fashioned. The sci-fi nerd in me wants something solid-state, more like Iron Man’s arc reactor. But sadly no-one outside of the fictional universe knows how that might work.So, will nuclear energy replace fossil fuels? Yes, but only some.