WATER HORIZON: on-demand renewable heating and cooling

Every day, Europe’s energy-intensive industries lose vast amounts of energy as waste heat. For example, industrial processes that require cooling often release large amounts of heat into the atmosphere. What if this energy could be captured, stored and reused? This was the starting point for Water Horizon, a French startup that has grown from a small team with a prototype, to a full-scale industrial solution.

A battery for on-the-go thermal energy   

Water Horizon has developed an innovative thermal battery that recovers waste heat and transforms it into on-demand, low-carbon heating and cooling. The project is the first to implement this technology at scale. Unlike conventional solutions, which reuse recovered heat only on-site, Water Horizon’s approach allows thermal energy to be stored, transported and released at different locations and times. For example, Water Horizon’s battery collects waste heat in an incinerator and delivers it to a sport centre, heating a swimming pool and cooling an ice-skating ring.  

Waste heat sources charge the battery, which can then be transported where energy is needed. Thanks to its modular design, users can access exactly the amount of heating or cooling they need, precisely when and where they need it. Through its cooling-as-a-service model, customers avoid installing expensive equipment and pay only for the cooling energy they consume, which does not emit any carbon emissions. 

Overcoming challenges 

When the project began in 2022, the technology had only been validated through a 10-kilowatt prototype. Scaling it up a hundredfold within a short timeframe presented both technical and organisational challenges. 

Three years later and with a €2.5 million grant from the Innovation Fund, the project has reached entry into operation and has been using two batteries since September 2025. This milestone marks the first full-scale deployment of the technology and a key step towards market uptake, helping build trust with current and future clients.

Cutting emissions and creating jobs 

Water Horizon’s high efficiency, low-carbon solution promises to replace traditional emission-intensive heating and cooling systems, directly contributing to Europe’s decarbonisation goals. It also promotes circularity and local value creation by reclaiming waste heat and redistributing it locally with efficiency and low-carbon intensity.  

The climate impact of the technology is significant. Each operating thermal battery avoids around 1, 400 tonnes of CO₂ emissions per year. The project is also delivering economic benefits. Since its launch, the Water Horizon’s team has grown from 7 to 36 employees, with further recruitment planned as activities scale up. 

A scalable solution for Europe’s energy-intensive industries 

As Europe accelerates its transition towards climate neutrality, reducing emissions from heating and cooling remains a challenge. This project will remain focused on scaling up energy recovery and distribution while expanding its presence.   

Looking ahead, Water Horizon also plans to build its own battery assembly plant, strengthening European industrial capacity and independence, while also contributing to the EU’s long-term decarbonisation and energy efficiency goals. 

Learn more about the Innovation Fund. 

Article published on 25 February 2026