Pathways to Decarbonised Steam

Our emphasis may often seem to be focused on optimisation. Making steam systems as efficient as possible is still a fundamental part of our business, and will continue to be so. The reasons why this makes sense will not disappear when the use of fossil fuels does.

Whatever path an industry decides to follow along the road to decarbonisation, it will always be a critical first step to maximise efficiency. Improving how heat is generated, delivered, and consumed not only reduces energy costs now, but it also creates the foundation for the next parts of the journey. But the elimination of carbon-emitting fuels is the ultimate goal - decarbonisation.

The stakes are high, and the challenge is significant. Thermal energy is vital to so many industries, and with so many differing ways of using it, there is no one track to reach net zero goals. Heat is responsible for two-thirds of all energy demand in industry in the US, but only 10% of this comes from renewable sources. In the UK, it's a similar story; 70% of UK industrial energy demands are for heat.

Using electricity that's been generated by renewable sources, or nuclear power, known as 'beneficial electricity' is a frontrunner. There are various reasons for this. The first is that it is a tried-and-tested technology, with electric boilers able to convert electricity into heat with an efficiency of almost 100% with minimal radiation losses from boiler surfaces. Then there is the potentially attractive capital cost, with one study finding electric boilers almost 40% less than that of an equivalent natural gas-fired boiler.¹

Further positives come with no changes needed in end-use processes, just in the boiler room itself. There are options available to electrify other parts of industrial processes, but these often need changes to existing production processes and technologies.

The major barrier to seeing increased take-up of this option is that electricity is still comparatively more expensive than fossil fuels. Even when this lowers, as is likely as renewables increase their share of electricity generation, grids will need to be expanded to supply the surge in demand.

That is why it's expected that CO₂ emissions would increase, temporarily, whilst the power generation and distribution industry catch up with the switch.

If produced sustainably, biomass is a promising prospect for replacing fossil fuels in some industries, although carbon may still be emitted from its combustion, at lower levels than fossil fuels. In Denmark, for instance, one energy company has already fully decarbonised its heat production, including providing steam for industry, by using biomass instead of coal for combined heat and power units (CHPs).

Still in the early stages, and still relatively expensive, hydrogen is seen as a real possibility to replace fossil fuels in high-temperature processes, and will be able to generate steam, at any required temperature. There are still issues in having to capture some emissions during its production and use, and controlling the burners is not as simple.

This emerging cleantech arena is very promising, especially given the intermittent nature of some renewable energy sources. Being able to capture excess or low-cost renewable electricity by warming a storage medium to temperatures of up to 400 C is currently far higher than those achievable with heat pumps. Work is also being carried out on capturing steam itself for short-term periods, useful where it is not needed on a continuous process basis.

Some industries, due to the intensive nature of their operations, are likely to continue to need fossil fuels, at least in part. Sometimes this might be to bridge periods where production cannot be halted, but carbon-free or low-carbon alternatives are not available.

Steam did not arrive at its dominant position as an indispensable means of industrial heat overnight. Nor do we need to assume we can no longer take advantage of its many benefits. The new chapter for decarbonised steam is already unfolding. It is less about abandoning what has worked so well for decades, and more about reimagining it for the future.

With the right commitment and innovation, industries can continue to harness the power of steam, but in a way that aligns with the global commitment to a sustainable future. The prospects look promising, and with collective effort, a decarbonised future is not just a possibility, but an impending reality.