The Nuclear Research and Consultancy Group (NRG) has begun what it says is the first thorium molten salt experiment in 45-years, testing a new design for a thorium reactor that could bring a new wave of nuclear power to bear in the emerging smart grid ecosystem. Should thorium salt prove viable, it could bring a whole lot of uncertainty into the mix, regarding a utility’s smart grid and renewables strategy, in an energy market that is on the verge of being heavily disrupted.
The race is on to bring the first thorium molten salt reactor (TMSR) online, and while NRG is focused on thorium molten salt as a fuel and the heat transfer medium, there are other approaches being explored by other national projects – hence the 45-year claim appearing a little confusing when you consider the Chinese, Indian, and Indonesian projects underway, which are not quite full-scale reactors yet.
In the announcement, NRG says that the reactors are significantly safer than today’s conventional nuclear reactors, and eliminate the issue of long-lasting nuclear waste – generating a fraction of the waste of a conventional reactor. The smaller reactors can also be deployed closer to the cities that will demand the most of their output, and because they can (theoretically) be refueled without downtime, they should be able to run for years at a time.
On paper, these thorium salt reactors could immensely confuse the long-term view for utilities, who have been getting to grips with emerging smart grid and renewable approaches. For storage and renewable developers and manufacturers, plentiful nuclear power would almost reverse the demands that are driving the growth of their offerings – as a traditional grid could essentially just swap-out if fossil fuel power plants and replace them with thorium reactors, answering most of the problems that these distributed smart grid systems promise to solve.
The current trend in smart grid technologies, fueled by cheaper and better battery storage, is the introduction of distributed generation capacity – typically photovoltaic solar panels, often mounted on the roofs of houses, but also in utility solar or wind deployments. Battery storage has helped to solve the problem of intermittent generation outputs from these renewable resources – something that was a huge barrier to adoption in the past.
The goal with these distributed resources was largely to tackle environmental concerns and regulation – with the tradeoff being their increased cost. However, the cost of these renewables has plummeted in recent years, often making the more cost effective than traditional generation resources.
Across the industry, coal plants have been mothballed, with renewables on one side driving cost-pressures, and cheaper natural gas on the other. Gas plants remain popular, but a number of conventional nuclear projects have been scrapped due to per-kWh cost of electricity falling below their minimum viable threshold. Westinghouse’s South Carolina plant collapse went far enough to lay parent-company Toshiba low.
So it looked like nuclear and gas would continue to be the non-renewable sources of choice over the next few decades, with renewables getting cheaper and cheaper and eventually cutting out gas and making new nuclear plant construction into an even more difficult question.
In that potential future, the high-voltage distribution networks would also come into question – given that they would be needed less and less to transport electricity around a national grid, as renewables allow electricity to be created and stored much closer to the point of consumption, and at much lower voltages that are generated by the conventional power plants.
So while some non-renewable assets would persist in that transition, and continue to require the high-voltage links to move their output to a city that might need them, it looked like renewables and storage would seriously squeeze the demand for new distribution networks.
While it is more efficient to transport electricity at those high voltages, the cost of stepping up 220V DC solar to the 400,000V AC current used by those power lines, and then the cost of stepping it down to a voltage usable in a home seemed to make it a pointless exercise.
So the long-term scenario seems that it will incorporate mostly renewable electricity generation, both at home-scale and at grid-scale, with battery storage addressing the ebbs and flow of both the supply and demand for electricity. Generation and storage would be located much closer to the point of consumption, and the need for a national high-voltage transmission grid would decline, leading to a likely decline in coverage.
Where possible, efficient non-renewable sources would be used to help provide the base-load demand for a grid, and for many countries that would constitute nuclear power – specifically the uranium-based fission plants are used today.
Nuclear fusion has been a pipe-dream for some time, but promises an effectively limitless supply of electricity – as long as researchers find a way to sustain the fusion reaction that generates the heat to drive the steam turbines that create electricity. However, we are still a long way from such a success.
With something like fusion, a high-voltage distribution grid would still be required, to transport the electricity to its point of consumption. However, the need for storage would be greatly diminished. If fusion reactors become viable, grid efficiency becomes a rather small concern – with cost becoming the main concern, as well as the operational safety of the plant, as nobody wants another Chernobyl.
Nuclear is therefore stuck in a lurch – it is being increasingly sidelined by renewable energy and battery storage, and fission still has problems in cost and the matter of safely processing nuclear waste. Environmental concerns from this pollution and radiation risk are not going anywhere fast, especially after the Fukushima incident.
However, the thorium-based reactors are a potential answer to the biggest problems with the current uranium-based nuclear reactors. There is a lot of hype surrounding the new approach, but thorium could be hugely disruptive. Thorium has garnered a lot of interest from Chinese research labs, and India has been an advocate, as it looks to bring electricity to its growing population. Indonesia is also pursuing a reactor.
The uranium fuel used by today’s reactors is a finite resource, that also poses a geopolitical risk as it can be turned into material for nuclear weapons – something that Iran is all too aware of, as its nuclear program has always drawn the ire of the global community, particularly the US and Israel.
As such, any country pursuing a new nuclear program is under immense scrutiny from the international community, and in a day and age where renewables and storage sound more appealing in emerging markets, it seems that nuclear is confined to markets in which it has already been deployed.
But thorium reactors don’t draw that same scrutiny, because thorium can’t be effectively weaponized. It is also a lot less risky to handle and process than uranium, and it is a more plentiful resource. But perhaps the best feature is that the nuclear reaction is not self-sustaining, which means that it can’t suffer a Chernobyl-style meltdown – as the only uranium needed is to start the reaction, after which only thorium is required.
Because physics is weird, thorium becomes uranium-233 when it is undergoing this reaction, being pelted with neutrons. Uranium-233 is a lot less dangerous than the uranium-235 used in conventional nuclear reactors.
The reaction, which uses molten salt as both a fuel and a coolant to control the reaction, generates the heat that turns water into steam, which then drives the electricity-generating turbines. Using molten salt isn’t a new idea – the US’s Oak Ridge National Laboratory was running thorium-based molten salt reactors in the sixties and seventies.
But the new NRG approach, part of a series of experiments called SALIENT (Salt Irradiation Experiment), is focused on creating a large-scale reaction that remains self-regulating. Most importantly, the fail-safe design (where the reaction just dies out, instead of spiraling out of control) is a huge benefit – as is the weaponization difficulty.