Meet the founders making clean energy work for everyone - Climate Tech Time
Last month, we opened the doors on the 34th edition of Climate Tech Time in the beautiful space at the Conduit. With such a stellar lineup, we knew we were in for a treat.
This evening brought together three speakers working at very different ends of the energy transition – yet the same theme ran through all of them. No one is building from scratch. No one is asking anyone to take a financial hit for the planet. And all three have found a place where doing the right thing and the profitable thing turn out to be the same.
Rob Hallifax of Windfall Energy opened with a provocation that yes, clean energy is wonderful. But what does it look like for the half of the UK that rents? Buffy Price of CarbonRe followed with a story that began at Amnesty International and ended inside a cement kiln in Czechia. And Lizzi Gold of RheEnergise closed with a question the industry had somehow overlooked for decades: what if the oldest form of energy storage just needed a denser fluid?
As Buffy put it so beautifully, here was a room of people who were pragmatic, passionate, and willing to dig deep.
Read on for the full roundup.
Getting a hardware startup off the ground
Rob Hallifax, co-founder and Chief Product Officer at Windfall Energy, kicked off the night by asking the audience to picture a clean energy home. Solar panels, an EV in the driveway, a heat pump outside – it sounds wonderful, except almost completely unrealistic for the 50% of people in the UK who either rent their homes or live in flats or small homes.
As energy bills rise, their options for saving money are limited. Rob wanted to do something about it.
He and his co-founder ruled out an AI SaaS product and decided on hardware. Their idea: a small battery that charges up with cheap, clean off-peak energy and gives it back during peak times. They knew hardware was hard and expensive, but they also knew that whether you’re building software or hardware, the core challenge is the same. You have to find people to care about your product and get the word out.
So, they broke the problem into small, testable chunks.
They started with a crude proof of concept, testing whether a small battery could genuinely save money by arbitraging between off-peak and peak energy. It worked, but it was a “bit techy” – and they knew that most people don’t buy technology for technology’s sake. So, they moved to a wooden box, spray-painted it black, put a plug in the back, and took it to a trade show.
This magical box quickly captured the attention of the press and energy companies. At this point, they’d spend around £1,000 all-in.
Next came form-factor testing – filling cardboard models in different shapes and sizes with bricks to simulate weight and test whether the product could stay under the 30kg courier shipping limit. They installed five off-the-shelf batteries in homes to understand the customer experience, and all the while, they progressed the visual design from 2D sketches to 3D renders to a physical model.
They travelled to China – introduced to suppliers through an advisor who runs a battery company and, separately, through a Scottish trade mission – to find manufacturing partners.
The night before this talk, they held a launch event for their first pre-order campaign. As they signed their first orders, the very same energy company representatives that had once wandered over to a black box on a trade show stand were in the room.
For Rob, the sharpest challenge with hardware is that mistakes are expensive in a way software isn’t. A £10 domain for a side project you’ll never finish is one thing; a £10,000 patent you never use is quite another. Hardware demands you get things right before you spend – which is exactly why testing in stages, and knowing what not to build yourself, makes all the difference.
Connect with Rob on LinkedIn to follow his journey, or check out Windfall Energy for more info on a plug-and-play battery designed to save money when solar panels or heat pumps are inaccessible.
“Building anything is hard, but if you’re thinking about building a hardware startup, it might not be as hard as you think.”
– Rob, Co-Founder of Windfall Energy
Reducing gigatons of emissions from cement
Buffy Price, co-founder of CarbonRe, followed. CarbonRe is an industrial AI company on a mission to reduce gigatons of emissions from energy-intensive industries, starting with the cement industry. Unlike Rob, Buffy and her team chose the B2B software route after she had what she called “an existential crisis”.
Her background, and that of her co-founder, Sharif, was at Amnesty International, where they used computer vision and language extraction to monitor human rights abuses, environmental damage, and hate speech. They were writing reports and sharing these with the UN and governments – monitoring fires, but not “putting any out”.
Through a connection, they met Dr Dennis Sommerbell, a fellow at the Institute of Manufacturing in Cambridge with a PhD in sustainability in cement. Buffy knew nothing about cement, but learned fast. It is the second most-used material on Earth after water, and it accounts for around 8% of global greenhouse gas emissions – more than shipping and aviation combined. Without changing the fundamental production process or requiring significant capital expenditure, there was an optimisation pathway to meaningfully reduce the fuel burned in cement production.
In the middle of the pandemic, with her company bought out, Buffy and Sharif went to Cambridge and decided to start a company.
CarbonRe focuses on the kiln, where limestone and other ingredients are heated to around 900 degrees (releasing around 60% of cement’s total CO2 through a chemical reaction), then moved into vast rotating kilns that burn enormous amounts of fuel to produce clinker, the main ingredient in concrete. Increasingly, producers are burning alternative fuels, which is good for emissions but drives variability into an already complex system.
CarbonRe has built a digital twin that sits on top of existing control systems, taking hundreds of sensor inputs from temperature to fuel mix and gas analysis, to build a minute-by-minute real-time model of what’s happening inside the kiln. Instead of reacting to problems, operators can anticipate what’s coming, develop strategies to burn more alternative fuels, and reduce fuel consumption more effectively.
They are now live in ten plants across India, Czechia, Brazil, Europe, and Turkey. At their case study plant, Mokra, a Heidelberg Materials site, they have saved 6,000 tonnes of carbon and nearly £700,000 in fuel costs in a single year. To put that into scale, with roughly 100 people in the room, each with an average London carbon footprint of 12 tonnes, you would need five times that number to equal the emissions saved by one small plant.
Connect with Buffy on LinkedIn to follow her journey or visit CarbonRe to learn more about how industrial AI is cutting emissions.
“Even with a 10% market penetration and an average of about 10,000 tonnes saved per plant per year, that’s 3.6 million tonnes of carbon not going into our atmosphere.”
– Buffy, Co-Founder of CarbonRe
First of its kind ‘high-density” hydro system
Lizzi Gold, Business Development Manager at RheEnergise, closed the evening with her path into the world of energy storage.
Lizzi originally studied chemistry at the University of Bristol, then spent time teaching English in Querétaro, Mexico, before feeling the pull back toward technology and science. In 2021, she joined RheEnergise as its first full-time employee and watched as the company grew from no office space to around 30 people across two offices in London and Montreal.
RheEnergise’s four founders met at a conference about energy storage in 2019. They saw the enormous need for storage – tens of terawatt-hours projected by 2040 – and were puzzled by the same thing: why was everyone so focused on batteries as the only solution?
Pumped hydro has been around for over a century and is the lowest-cost energy storage solution on the market, balancing the grid by absorbing power during oversupply from solar and wind and dispatching it back when demand spikes or renewable generation drops.
So, what if you could take that existing technology and make it better by an order of magnitude?
Typically, the problem with conventional pumped hydro lies in the sites themselves. Projects like Electric Mountain in North Wales, where vast infrastructure is hidden inside a mountain and capable of powering a city like Bristol for twenty-four hours, are extraordinary, but nothing like them has been built in the UK for 30 years. The “good sites” have already been used.
So, what if you could install this on small hills, closer to industrial demand, renewable generation, or constrained parts of the grid?
RheEnergise developed R19, a mineral-rich fluid more than 2.5 times denser than water, which means projects can be 2.5 times smaller and installed on slopes less than half as high as conventional pumped hydro requires. That opens up over 6,000 viable sites in the UK alone and over a million globally: an order of magnitude more than conventional pumped hydro can access.
They call this High Density Hydro. It retains all the benefits of conventional pumped hydro while shedding many complications, such as salmon ladders, environmental risks, and water abstraction permits, and their projects have received planning permission in as little as eight weeks.
And it’s already working. In January, RheEnergise’s demonstrator plant at Cornwood, near Plymouth – built on a spoil heap from a former mine site and funded by over £8 million from the UK government’s Long Duration Energy Storage competition – began generating electricity. The Guardian covered it as a first of its kind: a hillside battery proving that one of the oldest forms of energy storage can be deployed on even gentle slopes, underground, in places traditional hydropower could never reach. The plant generates 500 kilowatts, enough to power 400 homes continuously for a year, and has consistently met that target since switching on.
“What if we could take this existing technology and make it better by an order of magnitude?”
– Lizzi, Business Development Manager at RheEnergise
Follow Lizzi on LinkedIn to follow her journey or visit RheEnergise to learn more about High Density Hydro and the role it could play in the future energy system.
Across all three, the threads that connected Rob, Buffy, and Lizzi across magical black boxes, cement decarbonisation, and hillside batteries were that none of them is building from scratch. Rob is using mature battery components, Buffy is optimising an already complex system, and Lizzi is reinventing technology that is over a hundred years old.
Plus, whether it’s a renter with no access to renewable energy, a cement plant operator in India or Brazil, or a spoil heap in Devon, the opportunity is often hiding in plain sight.
Our next Climate Tech Time is on Wednesday, 22 April. Sign up for our newsletter for updates on all London climate events happening in the month, and follow us here for more updates.
