Insight and inspiration

Turning up the heat: how the FLEX reactor can decarbonise industry

Most people are aware of the role that fossil fuels play in electricity generation and in transport. They are also generally aware of the need to decarbonise these sectors of the economy, and the challenges involved in doing so. However, far fewer recognise that fossil fuel sources also provide another form of energy vital to modern society – namely, the high-temperature process heat used in industry.  

What’s more, the use of such heat, much of which typically requires temperatures greater than 300°C, takes place on a huge scale. For example, according to Ofgem, roughly half the energy consumed in the UK  amounting to 760 TWh per year – more than that used to produce electricity or for transport. Approximately 43% of this total is used for process heat applications. This covers a wide range of industries – including the manufacture of glass, steel, cement and aluminium, plus a myriad of chemicals and many other substances, without which our day-to-day lives simply wouldn’t function.

Fossil fuels currently supply almost all the process heat used by industry. So, there is a twin problem that needs to be addressed – firstly, finding a heat source that can replace fossil fuels at scale; and secondly finding a source that can produce this heat at least as cheaply as fossil fuels do. Unless the proposed solution competes on cost, there will be no incentive to decarbonise.

Let’s assess the low-carbon options. How might renewables fare in producing high-temperature heat? Using biomass or biogas involves combustion, which of course produces heat – but releases carbon to the atmosphere in the process. Although the logic of biomass means that this carbon is later reabsorbed, there must also be efforts to find even lower-carbon solutions.

While it’s true that geothermal and concentrated solar power (CSP) facilities primarily output heat, they face significant obstacles. Geothermal power faces constraints regarding where it can be used (for current technologies to be cost-effective, it’s limited to certain geological conditions). Similarly, CSP requires a large land footprint, making it inconvenient for industrialised areas (pumping heat over long distances is expensive and inefficient). Clearly, these can’t be used at scale without incurring large costs.

How about renewables such as wind, solar photovoltaic and hydro power? The problem here is that these primarily produce electricity rather than heat. While it’s perfectly possible to produce heat via electricity, the problem is that doing so involves converting electrical energy into heat, and there will always be losses in the conversion process that reduce efficiency and drive up costs.

How about using the electricity from renewables to produce hydrogen via electrolysis and then burning the gas to provide heat? This runs into the same problem – the laws of physics mean this process will never be as efficient than simply producing the heat directly.

To be clear, renewables are a vital tool in the fight against climate change. Their ever-faster rollout has outstripped predications from even a decade ago, and this is cause for genuine optimism. But this does not mean that we can rely upon them to solve all our low-carbon energy needs. Nevertheless, they give confidence that the sector should trust innovative and emerging technologies to fulfil their potential, and to become part of the solution in a relevant timeframe.

Thankfully, there IS a low-carbon solution to the problem of producing heat: advanced nuclear plants. Molten salt reactors or high-temperature gas reactors can reliably and efficiently produce low-cost process heat on a large scale. And this is where the FLEX reactor can help.

Most conventional water-cooled reactors today operate at high pressures and (relatively) low temperatures (around 300°C or so). But thanks to its use of molten salt as a coolant, the FLEX reactor operates at atmospheric pressure and outputs high-temperature heat at 750°C.

This sounds incredibly hot compared with, say, the maximum temperature of your kitchen oven, but in fact it’s comparable to or lower than many other common heat sources. For example, a wood fire burns at around 600°C or more, a candle flame at up to 1,400°C, and a kitchen gas hob at approximately 2,500°C. Additionally, engineers and scientists know how to safely manage and control these temperatures – after all, we at MoltexFLEX do it every day in our lab in Warrington.

Given that as much as two-thirds of all heat use in European industry is below 700°C, the FLEX reactor is ideally placed to supply heat for a huge range of different uses.

It’s not just the fact that we can create heat at useful temperatures. Unlike large, conventional nuclear power plants, each FLEX reactor is incredibly compact – a single unit creating 40 MW of thermal energy occupies an area roughly the size of a tennis court. They can be built and installed quickly at a wide variety of industrial sites, directly supplying heat for many different processes.

Finally – and crucially – FLEX reactors can generate this heat at a low cost. For direct industrial use, heat can be created at a levelised cost of approximately £10/MWh or even less. If low-carbon heat sources can’t compete with fossil fuels on an economic basis, it will be difficult for many different industries to decarbonise on a wide scale.

Moreover, the fact that FLEX reactors can produce heat so cost effectively is a boon for developing nations. While richer countries such as the UK might be able to pay a premium for clean energy, poorer nations cannot – making it imperative that low-carbon energy sources can compete on cost.

This ethos – the need to provide abundant low-carbon energy at a low cost – lies at the heart of the thinking behind MoltexFLEX technology.

To keep the rise in average global temperatures below 1.5°C , the world needs a range of solutions to a range of challenges – electricity, transport, domestic heating and process heat are just a few of these. While renewables, and conventional nuclear will play a role, small-scale and advanced nuclear technologies must be major contributors – and provide a much-needed solution to a frequently overlooked problem.

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