ECOVAT Seasonal Thermal Energy Storage & Provider for Grid flexibility

Photos used with permission from Ecovat

Netherlands, Belgium, Czech Republic, Germany, Spain, Sweden


Replacing fossil fuel with renewable energy sources in the energy production sector is challenging as renewable sources are highly dependent on both seasonal and day-to-day changes in weather. This increases the difficulty of making renewable energy a competitive option compared to fossil fuel on a large scale.


The ECOVAT energy system constitutes a decentralized energy supply chain covering production to consumption. Producing and storing thermal energy from either wind power or solar thermal sources allows for a flexible energy system that is adaptable based on local weather conditions and reduces the need for back-up solutions. By decreasing the dependence on electricity to meet the heat demand, the peak electricity demand will be lowered, resulting in reduced grid generation requirements. The system has a lower building and maintenance cost compared to existing options while being highly efficient with less than 10% heat loss over a six-month period.


The Ecovat demonstrator built in Uden, the Netherlands in 2014 – 2016 was a great success which enabled Ecovat to reach the market introduction phase. In 2019, Ecovat expects that with public investment, the first seasonal storage tank will be placed in the ground in Arnhem. This system will provide 500 households with sustainable energy throughout the year.


Ecovat enables 100% renewable energy for heating and cooling. Additionally, Ecovat ensures predictable costs for heating and cooling. Financial savings, at a national system level, were calculated by Berenschot as an annual reduction. The cost saving with Ecovat is between € 97,000 and € 167,000 per year through the elimination of peaker plants and reinforcement costs. For the Netherlands, the system has a potential annual cost reduction between € 380 billon and € 650 billion per year. To realize this potential, there is a need for greater project financing and funding for investments and upscaling.

Useful links

Ecovat website

Case study