An Introduction to a ‘Hotter’ Topic

As we tentatively progress on several fronts towards a greener future, it is imperative that we continually reassess the prioritisation of our efforts. Returning to sectors previously dismissed as ‘hard to abate’ armed with new, innovative solutions can present large opportunities for CO2 emission reductions. Whilst current global events have highlighted the cost of domestic heating and the subsequent challenges of decarbonising our homes as a ‘hot’ topic, it is time we revisited domestic heating’s bigger, uglier sibling: industrial process heat (IPH).  

Solely judging from the temperatures required, IPH is a much hotter topic – and that is before the associated CO2 emissions are considered. Just under a quarter of global greenhouse emissions are generated from energy use in industry.  Despite this, the discussions of how to decarbonise these emissions continually flies under the radar. This issue is starkly demonstrated by comparing the share of funding this sector has received thus far versus the share of emissions released. CLT analysis reveals that less than 1% of the $104.3 billion invested in climate tech by venture capital since 2020 has been deployed into innovative decarbonisation solutions for IPH. 

There are several reasons for this disproportionate lack of funding. Firstly, IPH is not concentrated neatly in a single box. Emissions are produced from a vast variety of processes through a multitude of different technologies in a broad swathe of sectors. To find comprehensive data that spans across all that IPH heat entails is difficult (as noted in the CCC’s recent report), even when you can devote several weeks of your working time to doing so. Without conscious effort to counter this, IPH emissions are easily overlooked. 

This relates to a second issue; the lack of transparency from many of the emitters in this space. Whilst carbon reporting is steadily becoming a staple requirement, lack of openness concerning process specifics and technologies creates a difficult environment from which to externally generate targeted solutions. This only adds to the myth that these emissions are ‘hard to abate’ – a state of affairs industry leaders are not actively seeking to dispel. 

In of itself, this might not be too much of an issue if rapid change were likely to come from within. However, the nature of many of the industries involved is that of a slow-moving beast. Up until now, the low prices and high temperatures provided by fossil fuels have been more than sufficient, and despite the existential threat posed by global warming, why change? With large, expensive, fossil fuel guzzling assets at risk of becoming stranded in a decarbonised world, many industry players will not jump until the very last second before they are pushed. 

To combat the inability of industry to move at the pace required to instigate meaningful change, we must turn to innovative disruptors for solutions.  

The Complexities of Industrial Process Heat 

Unsurprisingly, there is no ‘one size fits all’ solution. There are a multitude of complexities to consider when assessing the decarbonisation options for any particular process. For example, the quantity of heating required, the duty cycle of the process or hygiene regulations for the final product. Then there’s complications introduced by the heating technology such as heating output, fuel availability and ease of integration. Finally, the specifics of the industrial site itself are also worthy of consideration: waste heat availability, geographical location and physical space constraints to name a small few. It is an easy world to become lost in the detail of.  

Therefore, to better understand the space in which these innovators are operating, and importantly how far-reaching their solution may be, some attempt must be made to simplify the complexities involved. While it is tempting to remain siloed by sectors by first developing technologies to decarbonise processes in the cement industry, then paper and pulp and so forth, a much more productive view is to consider the heat grades required by processes across all industries. This cuts across the sector divide and leaves three broad categories for solutions to target: low grade heat (often defined in the range of 0C to 150C or 200C, comprising 44% of energy requirement), medium grade heat (200C to 400C, comprising 6% of energy requirements) and high grade heat (anything higher than 400C, comprising the remaining 50% of energy requirements and some of the harder emissions to reduce). 

It is, of course, too simplistic to say that a solution that operates in the low grade temperature range can cater for the heat requirements of all processes in that temperature range, but it is a useful starting point for cross comparisons.  

How to Decarbonise Industrial Process Heat 

There are six broad themes into which decarbonisation solutions for IPH fall: 

1. Electrification: direct electrification technology (electric arc furnaces, infrared, direct resistance heating etc.) and heat pumps 
2. Alternative fuels: biomass and hydrogen 
3. Renewable heat sources: solar thermal and geothermal 
4. Energy efficiency: machine learning assisted tools (such as Clean Growth Fund’s CarbonRe), resource efficiency and grid integration technologies 
5. Waste recovery: waste heat utilisation, circular feedstock and CCUS (such as Clean Growth Fund’s Nuada) 
6. Thermal storage 

To deep dive into all of these solutions would require a full novel instead of a brief blog post, and so instead I will today focus on heat pumps, solar thermal and thermal storage. 

Heat Pumps 

These are not your eco-friendly neighbour’s heat pumps. Whilst operating on broadly the same principle, the addition of innovations such as improvements in the compressor and the combination of multiple cycles have greatly increased their capabilities. Industrial sized heat pumps can push output temperatures of up to 200C, such as one of Clean Growth Fund’s latest investments, Futraheat, though most currently deployed systems target 120C and below. For the lowest of temperature requirements, ambient air is an ample heat source, but for more useful temperatures the utilisation of waste heat is required. 

Heat pumps hold a few advantages that make them an easy go to decarbonisation solution at lower heat grades. They are a small footprint, relatively low capex, low opex technology with a remarkable ability to upcycle heat with only a small input of external energy, boasting efficiency values of between 300-400% (for every unit of electricity provided, 3-4 units of heat are transferred). As electricity prices remain high, this efficiency is how heat pumps will make a competitive entrance onto the scene.  

Solar Thermal 

While it is true that the sunny pastures of the UK might not lend themselves to being suited for solar thermal installations, they are an excellent option for locations with less temperamental weather. That is not to say that solar thermal solutions are totally unviable in the UK – they just likely won’t reach the same output temperatures as elsewhere and will certainly rely on supporting technology such as thermal storage to be effective. Proven and already deployed solar thermal solutions can reach temperatures around 400C, making them ideally suited to catering for medium grade heat and below. Innovative solutions based on concentrated solar power technologies can reach temperatures of over 1000C but have yet to be deployed outside of pilot plants.  

The obvious upside to solar thermal technology is the very low opex required – there are few moving parts necessitating regular maintenance beyond a gentle cleaning, and the sun is a free energy source. However, this comes with the drawback of a (very) large footprint and a difficultly in extracting heat at night or under dense cloud cover, restricting reliable use to industrial sites with favourable environmental conditions or processes that can cope with an intermittent heat supply. 

Thermal Storage 

Thermal storage will be a crucial tool in the box, enabling many of the other decarbonisation solutions to reliably cater for industry’s vivacious appetite for heat. Storage solutions find themselves well placed to be deployed in several scenarios: as a ‘point of heat generation’ source through direct electrification, as a supplemental technology to intermittent renewables such as solar thermal, or as a component of a waste heat utilisation cycle. Many innovators are focusing on modular designs, with most aiming to provide for high grade heat requirements and below. Thermal losses from these systems are already in the low single figures of percentages over a day. 

The ability of thermal storage to smooth the energy output from renewable sources, both electrical and thermal, enables advantage to be taken of the fluctuations in electricity prices, resulting in more cost-competitive decarbonisation solutions. The flexibility offered by the modular designs allows for a phased capex, with the ramping up of capacity as required. The lack of moving parts requires little maintenance, and so opex costs are mostly associated with the choice of energy source. 

The Landscape of Innovators  

Armed with a greater understanding of these technologies, it is time to take a look at the innovators hoping to disrupt the current status quo of carbon intensive industry. Each company has been grouped by the category of their solution, and approximately sorted by the highest stated temperature output of their technology. 

Who have we missed in these spaces? Who are the most exciting innovators working to decarbonise industrial process heat using other technologies? Let us know! 

This article was written by Michael Cullinane, Analyst with Carbon Limiting Technologies