Industrial waste heat to clean power with storage
The interview
Enerin CEO, Arne Høeg, and KTH Royal Institute of Technology Assistant Professor, Silvia Trevisan, spoke about the European funded SUSHEAT project in a recent interview filmed for Sweden’s largest media platform for climate action “We Don’t Have Time”.
The broadcast was streamed on the sidelines of the 10th International Energy Agency (IEA) Conference on Energy Efficiency held in Brussels, 12-13 June, 2025. Strategic Communications Consultant, Nick Nuttall, hosted the event that was co-organised by We Don’t Have Time and SUSHEAT.
SUSHEAT is validating a heat upgrade system for industrial processes with Enerin’s heat pump at the core of the project, although the project is not just about the heat pump, as Silvia Trevisan explains below.
The session focused on how the SUSHEAT system could transform waste‑heat recovery and process efficiency across multiple sectors by harnessing “Waste Industrial Heat into Wealth: New Innovations, Big Opportunities”.
The Enerin CEO and the KTH Assistant Professor were joined by the European Heat Pump Association Director General, Paul Kenny, and European Commission Directorate-General for Energy—Just Transition, Consumers, Energy Efficiency and Innovation, Rosalinde van der Vlies.
Watch the interview HERE.
Follow Arne Høeg on We Don’t Have Time—mechanical engineer and entrepreneur with 10 patents and designs in the market—including industrial heat pumps, water turbines and subsea drones.
How our world is fuelled
According to Silvia Trevisan, writing for a related EU project I-UPS, a quarter of global energy demand is consumed for industrial heat purposes, with nearly 90% fuelled by non-renewables, generating 40% of global CO2 emissions.
Fossil fuels are used to produce high-temperature heat, and cooling, for the manufacturing of food, drink, chemicals, and many more things. Typically, factories need heat in the form of steam or high-temperature water, and for other uses, such as thermal frying oil, for chips and fries.
Recycling industrial heat to fight fossil dependence
In the interview, Arne Høeg emphasized the often‑ignored potential of re-using industrial waste heat. “Almost all industrial heat is wasted—lost through chimneys, into rivers, and into other streams…that heat is not going really into the product. It’s used in the process and then it’s wasted.”
Contrary to common belief, low-grade process heat can be reclaimed for regeneration using industrial heat pumps. Heat pump systems can both cool and generate high-temperature heat. Co-generating cooling and heat reduces energy consumption, water use, and chemical treatment in cooling tower operations.
Why isn’t waste heat reused more?
In the interview, Arne Høeg talked about Enerin’s heat pump installation at one of Norway’s biggest sustainable fish food producers dedicated to using the whole fish—Pelagia—which is a use-case on SUSHEAT.
He explained that factory processes operate in batches which require different heat temperatures for different stages of the process. “What we see is when you process the leftovers, from what we want to eat from the fish, is that the available waste heat is changing all the time”. For example, on the factory floor, a tank may need to be rinsed, then the fish remains are boiled into a sludge, which is later dried into feed.
“One minute the heat requirement is at 90 degrees, and the next time it’s at 40 degrees from the process, and maybe tomorrow, it may be cold Arctic seawater as the heat source,” he said.
Enerin’s HoegTemp heat pump is built to handle these variations. It can draw heat from low-grade process heat, ambient air, fancoils, wastewater, seawater, or river water—sources that fluctuate in temperature seasonally and daily. It also adapts to the changing steam pressures required by factories, from low to very high, with resilience to real-time temperature and pressure oscillations.
“So what we see is that in the real-life operation of the heat pump is that the heat pump adapts. It is very robust to those fluctuations and that it can adapt to whatever temperatures they need (the factories) and whatever source temperature they have.”
While many industrial heat pumps struggle with low or unstable waste heat due to thermodynamic and efficiency limits, HoegTemp is designed for this complexity. At Pelagia, a SUSHEAT project use case, Enerin’s system handles heat inputs from 15–90°C and delivers steam at 130–180°C, with operating pressures between 2 and 8 barg.
Conventional systems typically need a stable, high-grade heat source. When input temperatures drop—say, lukewarm water or factory air—the temperature lift needed to reach usable industrial heat (often above 150 °C) becomes too large or uneconomical. Enerin’s adaptable design addresses this gap, unlocking energy that would otherwise go to waste.
The essence
Enerin’s reverse Stirling heat pumps can lift temperatures from as low as -30 °C to steam or hot water up to 250 °C in a single step, achieving Carnot efficiencies (energy efficiencies) sometimes exceeding 60%.
Høeg highlighted sectors like pharmaceuticals, where processes often require sustained heat between 180–250 °C for drying processes and for chemical reactions in the pharmaceutical industry. In his previous industrial heat pump R&D, totalling over 30,000 operational hours, with the additional 12,000 clocked at Enerin, Høeg had experience with delivering both iced water and heat to a dairy plant.
By allowing Enerin’s heat pumps to co-generate cooling by taking in heat sources at the lowest temperature level—rather than recovering the condenser heat from the existing chiller—improves the overall system efficiency and enables our heat pumps to take advantage of the freed-up grid capacity from idle chillers and cooling towers.
Cost and complexity
The challenges, however, lie in cost and complexity, Høeg said in the interview. Traditional high-temperature heat pumps must be customized to each facility, driving up engineering costs and time. “That has led to heat pumps being quite expensive because they have to be designed to each individual customer,” he noted. “Big projects, very costly.”
But the modular and scalable HoegTemp and the SUSHEAT heat upgrade system could produce reliable energy systems at a better price for industry. These technologies aim to reduce reliance on fossil fuels presently supplying a substantial part of the industrial heat energy mix.
SUSHEAT pushes the boundaries of industrial heating
Silvia Trevisan said that while the heat pump is the centre, the core of SUSHEAT, there are a number of other things around it.
“We have a novel thermal energy storage—you can think of it like a battery, but for heat,” she said. Using phase change materials, the system stores and releases heat through melting and freezing. “So we have good control on the temperature and we can deliver (the energy), and this goes back to the requirements of industry”. Flexibility is key. SUSHEAT aims to electrify industry—when electricity is cheap and renewable sources are abundant.
The team is also exploring how solar thermal fits in: when it outperforms heat pumps, when it complements them, and how the two can work together, coupled. With increasing system complexity, AI-powered smart controls will tie everything together. “And these are all the additional things that we are bringing together on SUSHEAT, basically, to help the heat pump,” Trevisan said.
By 2026, the full system will be validated at KTH, showcasing how heat pumps, smart storage, solar, and AI can combine to drive decarbonization and energy-efficient solutions for industry. SUSHEAT can create new markets and opportunities by capturing, storing and using renewables in an intelligent way.