We sat down with Helle Ehrenreich, CEO of Micro Thermal Energy, to hear how she and the team plan to bring renewable baseload energy closer to the point of demand.
1. What is Micro Thermal Energy building? What problem does it solve, and how does the system work?
We’re developing ‘micro’ geothermal power installations that make geothermal energy lower cost and more accessible.
Conventional geothermal only works where high temperatures sit close to the surface, which rules out most of the world. We’re focused on making it work in the places it currently can’t. It’ll be around 200kW per unit, generated and used locally, with no grid connection or major infrastructure needed for distribution. Our solution is small and modular and installed in the size of a large shipping container. We predict the total footprint in production to be around the size of a tennis court, much smaller than the footprint of solar or wind for the equivalent power.
The compact size means we can get close to the site that will use the energy, whether that’s a medium-sized factory, a hospital, or a university.
We’re also excited about the idea of building micro thermal installations across Europe to boost EV charging infrastructure for trucks and vans that need dense charging infrastructure. And reaching the parts of the world that don’t have access to (continuous) electricity is a great ambition of ours.
2. What is Thermawynd®?
It’s a plug-and-play modular 200kW system that fits into a shipping container and delivers electricity round the clock. It features a new, innovative type of heat exchanger that we’ve developed and filed a patent for.
How it works: we circulate cold supercritical CO2 down a deep hole that we’ve drilled, where it gets heated up and circulated back to surface by our heat exchanger. At the surface the flow is expanded through a turbine connected to a generator to create electricity.
The heat exchanger is currently at TRL 3, while the rest of the system sits between TRL 5 to 7. CarbonFix’s funding is going to enable us to do a proof of concept so we can move the heat exchanger up to TRL 5.
Our system is closed-loop which is a huge advantage environmentally. We completely case our wells so there’s no contact with the surface or the earth.
Current geothermal power systems drill down to 5-7 kilometers to achieve temperatures of around 300C. By targeting just half of that depth – about 2500m – we can make a big dent in the Capex needed. We are also investigating the option of extending the asset life of existing oil & gas wells in order to both reduce capex and minimise CO2 footprint.
“Thermawynd” is a play on words reflecting that we are generating a wind effect caused by thermal energy. The spelling of wind with a ‘y’ links back to when we turned a corner; it’s the name of the first person in a large corporation who saw something in what we were trying to achieve.
3. What’s your origin story? How did Micro Thermal Energy come about?
During COVID, the three of us (Helle, Simon Bakshi, Neil Wands) would have G&T Zoom nights. We talked about everything, but mostly about energy, because we all have a background in the oil and gas industry.
We kept coming back to the same question: what can actually deliver clean power continuously? Nuclear is the usual answer, and none of us found that satisfying for various reasons. Geothermal is the other one – heat that’s always there. The more we looked at it, the more we couldn’t understand why nobody was trying to make it more accessible.
One night we decided we were going to do something about it. Fueled with optimism and trust in our capabilities, we concluded: If anyone can do this, we can! That same week we decided to start a company that would enable widely accessible geothermal. If we hadn’t done it so quickly, I wonder if we’d have done it at all.
It was a hard journey in the beginning to find interested parties and gain traction, especially because we didn’t have a prototype. We turned a corner when we caught the interest of the managing director of a manufacturing plant in Wales, and on the back of an Innovate UK grant, we kicked-off.
4. Which parts of the system have been validated, and which assumptions still needs to be proven?
We are taking a two-stage approach. We have designed a proof-of-concept to validate the performance of the heat exchanger against our modelled design parameters. This includes the manufacture of a prototype heat exchanger and will enable us to measure how the heat exchanger will perform compared to what we’ve modeled. We need to see if the simulations and assumptions made with our modeling actually stack up in an operational environment.
The next step is to perform an installation in a pilot well to evaluate the total process from downhole heat transfer to electricity generation. This project will also include a prototype turbine manufacture. The purpose is to test the whole system in a depleted gas well of a few thousand metres. We will be kicking this project off mid-2027 with a targeted execution in early 2028.
5. What are you most proud of so far?
I’m most proud of how we have worked together as a team and stuck it out. We are quite resilient and work really well together with complimenting skillsets and personalities. I am also proud of the rewards and grants that we have achieved. Innovate UK awarded us the Women in Innovation award in 2025 and we also received the Badge of Honour from Women Tech EU. This year we were selected for the prestigious TechX Accelerator programme run by the Net Zero Technology Centre in Aberdeen. This is also where we will be running the POC test. Finally, a big shout out to some fantastic people at Cranfield and Warwick Universities, with whom we have collaborated closely.
6. What are the hardest obstacles?
There are so many stakeholders, and it’s incredibly complex. As with all innovations, we have many proof points to achieve and technical challenges to tackle, but we remain dedicated to demonstrating that geothermal energy can be the next renewable source of power to scale.
Apart from developing and proving our own tech, one priority is to find a good drilling partner as this will enable better commercial metrics. We can support their innovation towards drilling optimization, and they can support us by sharing risk or cost through novel contract partnerships. To do this we need to develop a trusting and collaborative environment across the industry.
Planning permissions is a challenge that gets a lot of attention, but there are many legislators who want clean electricity that is free of the grid constraints, so we think there is an incentive to overcome this, particularly if they see increasing investments backing geothermal.
If we can get a few success stories at a community level, hopefully the rest will come.
