Pathways to Decarbonised Steam
Towards a Positive Future
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.
Why steam has kept pole position
How steam came to be so prevalent in all kinds of industry is not in question. It is a matter of physics; or more precisely, thermodynamics. Steam’s capability to transfer heat energy to where it is needed is unmatched by anything else. The relative ease by which it can travel distances – even miles in a large plant – means it is a tremendously efficient medium too. Industries do not make decisions lightly; if they use steam, it is because no better alternative has yet been found.
In fact, it isn't actually steam that needs decarbonising. As we have long advocated, steam is natural technology performing at its best. The issue comes from how we generate it in the first place.
It's an important distinction, because often steam gets lumped together with the fossil fuels that have traditionally been used to raise it - gas, oil, and coal. We now know that these energy sources are harming our planet by elevating levels of greenhouse gases to a point where it's detrimental.
Steam does not; it is not an energy source, it is an energy transfer medium.
For the countless industries that need steam to operate at the levels of output and efficiency we have all come to enjoy, that is good news. We just need to move along the path to decarbonising steam's production.
Just like the wheel, steam doesn't need reinventing
Cast your mind back a few years, and think how many electric vehicles (EV) you saw on a daily basis. Very few, with the internal combustion engine, fuelled by petrol or diesel, completely dominant. Then, in 2003, Tesla appeared on the scene and tirelessly promoted the promise of electrically powered cars. Advances in battery technology, and ultimately more affordable models, increased take-up of the decarbonised options. Today, sales of EVs are rising exponentially, albeit from a very small base.
But one thing has not changed; they still rely on the wheel. The physics behind an axle combined with wheels hasn't changed much in over 6,000 years, but the means of powering it has. And, just as with the wheel, it is entirely possible to keep all the benefits that steam offers by changing the way it is produced.
Five key routes towards decarbonised steam
The versatile nature of steam's use in industry means every industry will need to choose its own route to decarbonisation. It might not even follow a linear A-Z route; there are more likely to be various measures that can be employed to reach that final goal.
But, if steam is still considered a vital part of that industry's operations, at some point finding a way to use it that does not result in carbon emissions (or significantly minimises them) is critical. Right now, there are five main contenders to meet this challenge.
Electrification
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.
Biomass
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).
Low-carbon hydrogen
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.
Thermal storage
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.
Carbon Capture and Storage (CCS)
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.
Sources
1Ali Hasanbeigi, Lynn A. Kirshbaum, Blaine Collison, and David Gardiner: Electrifying U.S. Industry: A Technology- and Process-Based Approach to Decarbonization, 2021.
Edward Rightor, Andrew Whitlock, and R. Neal Elliott: Beneficial Electrification in Industry, July 2020
Ricardo: Pathways to Industrial Heat Decarbonisation, November 2022.
M. Jibran S. Zuberi, Ali Hasanbeigi, William R. Morrow: Electrification of Boilers in U.S. Manufacturing, 2021.
Lisa Neusel, Simon Hirzel, Matthias Rehfeldt: Still alive, but different in the future? Decarbonisation of industrial steam boilers from a multi-dimensional perspective, 2022.