Ask most people working in industrial energy about decarbonisation and the conversation usually goes one of two ways. Either it heads straight to hydrogen, which is promising but largely dependent on infrastructure that doesn't exist yet at scale. Or it goes to full electrification, which for many high temperature processes is genuinely not viable today. Both are important conversations. But they tend to crowd out a third option that is already working, already installed, and already delivering results in factories across the UK.
Waste heat recovery industrial applications are not new. The engineering is understood. The commercial case is real. And yet it remains one of the least deployed solutions in energy intensive manufacturing. This piece explains why that gap exists, and what sits on the other side of it.
Why Drying Gets Overlooked
Most of the public conversation about decarbonising heavy industry focuses on the most dramatic part of the process: the kiln, the furnace, the part where the product is actually fired or formed. These are hard problems, and they deserve attention.
But drying, the stage that happens before firing, is where a significant and often underestimated share of energy goes. In ceramics, brick and tile manufacturing, large volumes of moisture need to be driven off the product before it can go into the kiln. That requires heat, typically supplied by gas burners, and delivered continuously across large chambers or conveyor systems.
This stage doesn't get talked about much because it doesn't require the same temperatures as a kiln, and it doesn't carry the same technical complexity. But precisely because of that, it is the easiest part of the process to address. Industrial process waste heat recovery applied to drying requires no fundamental redesign of the product or the production method. It captures heat that already exists on site and puts it back to work.
Where the Heat Is Actually Going
In a typical brick or tile manufacturing plant, heat exhausted from drying chambers is vented into the atmosphere through stacks. Along with it goes water vapour, recovered from the product as it dries. Both are simply lost.
At Wienerberger's Warnham brick works, the site had seven large drying chambers, each exhausting warm, moisture-laden air to atmosphere. That warm air represented recoverable energy that the site was already paying to generate. The waste heat recovery system installed there captures that exhaust, condenses the moisture back into water, and feeds it through high temperature heat pumps to supply heat back into the drying chambers.
The result: a targeted 18% reduction in gas consumption per kWh per tonne of product, and 3,700 tonnes of CO2 cut per year. The site also recovers water that it feeds back into production, reducing what it draws from mains supply.
This is not a marginal improvement. It is a structural shift in how the site uses energy, built on capturing what was already there.
Research into batch kiln operations has produced an even starker number: estimates suggest that up to 90% of heat generated in some batch kiln processes is currently wasted. Even if only a fraction of that is recoverable in practice, the scale of the opportunity is considerable.
The Technology Already Exists
One of the most persistent misconceptions around industrial energy efficiency is that the solution to waste heat is still being developed. It isn't. Energy recovery from waste heat using heat pumps, heat exchangers and heat recovery towers is established technology. The engineering challenges are well understood, the components are commercially available, and the systems have been built and commissioned in working industrial environments.
High temperature heat pumps, specifically, have advanced to the point where they can deliver hot water at temperatures approaching 90 degrees Celsius. That is sufficient to replace gas burner heating in drying and curing applications without modifying the underlying process. For sites running off-grid on oil or LPG, the switch can be even more compelling, since electricity replaces a fuel that is both expensive and difficult to manage at scale.
Waste heat recovery systems of this kind are not experimental. They are industrial energy recovery systems with measurable outputs, trackable performance, and a clear maintenance profile. The risk profile looks nothing like a first-of-its-kind technology bet, because in most cases it isn't one.
The Commercial Benefits
The commercial case for waste heat recovery industrial applications runs across several lines at once, which is part of what makes it more robust than single-variable energy investments.
Energy cost reduction
Capturing and reusing heat that would otherwise be vented to atmosphere directly reduces gas consumption. For a site where energy is a material line on the cost base, that is a predictable, ongoing saving.
Carbon cost reduction
With the UK carbon levy currently around £50 per tonne of CO2, and forecast to rise, every tonne of carbon removed from the process has a quantifiable financial value. Industrial waste heat utilisation reduces combustion directly, which reduces carbon liability directly.
Predictability
Gas price volatility is a budget forecasting problem as much as it is a cost problem. A site that has reduced its gas dependency through heat decarbonisation solutions has also reduced its exposure to gas price swings. That has a value that doesn't always appear in simple payback calculations but matters considerably to a finance director looking at a three to five year cost model.
Water recovery
For sites where drying processes exhaust moisture, recovering that water can meaningfully reduce mains water consumption. At Warnham, recovered water is fed directly back into clay mixing. That is an operational saving that sits alongside the energy saving, not instead of it.
Why Adoption Is Still Slow
Given a working technology, a clear commercial case, and real-world proof, the obvious question is why more sites haven't moved. The honest answer is that it comes down to capital, not conviction.
Industrial process waste heat recovery projects require meaningful upfront investment. For many manufacturers, particularly SMEs, finding that capital while managing day-to-day production costs is genuinely difficult. Payback periods of three to five years are considered acceptable in some organisations and a barrier in others, depending on how the finance committee frames the risk.
For a while, the Industrial Energy Transformation Fund helped close that gap by providing capital support that shortened effective payback periods and made otherwise marginal projects viable. Several manufacturers had scoped and planned waste heat recovery projects on the assumption that funding would be available. When the fund closed without a follow-on round, a number of those projects were shelved, not because the engineering changed, but because the numbers no longer worked without support.
This is the central frustration in industrial energy efficiency right now. The gap is not technical. Carbon capture, hydrogen and other long-term pathways are still years from being deployable at scale for most manufacturers. Industrial energy recovery systems that use waste heat are ready today. Closing the investment gap, through output-based contract mechanisms, capital support, or reformed funding schemes, is what determines whether that readiness translates into actual deployment.
What Comes First
Hydrogen may be part of the long-term answer for some processes. Full electrification may follow for others, where grid capacity and process chemistry allow it. Carbon capture will have a role in certain industrial contexts where combustion emissions are unavoidable.
But none of those are available at scale right now, and all of them carry a higher risk profile than what is already proven. Industrial energy efficiency improvements through waste heat recovery, applied first to drying and then extended to other heat-intensive stages, offer a lower-risk, lower-cost starting point that delivers results during the years when everything else is still being figured out.
The heat is already there. The technology to capture it exists. The question for most sites is simply when the investment conditions make it possible to act.