Heat as a key to the energy transition: from source to user

The interaction between heat sources, storage, conversion, distribution, and use determines the success of the heat transition. Heat networks are still too often developed as isolated local systems. One municipality may leave residual heat unused, while the neighbouring one invests in expensive new sources. This leads to missed opportunities and unnecessary costs.

TNO tackles this fragmentation with an integrated approach. We’ve developed the Design Toolkit, a work platform with open-source tools that help municipalities and heat companies make optimal decisions together. By smartly linking heat, cooling, and electricity systems, we create a robust energy system that flexibly responds to supply and demand throughout the seasons.

Read more about system integration.

Geothermal energy provides a constant flow of sustainable heat from deep underground. It can heat entire neighbourhoods, but drilling wells is expensive and comes with uncertainties – you never know exactly what lies beneath.

We reduce investment risks with smart tools and additional research. ThermoGIS maps the heat potential using data from thousands of existing wells. The SCAN programme fills in the gaps with new seismic data.

Real-time monitoring adds another layer of information. For example, the Digital Twin Gemini monitors the performance of operational installations and predicts when maintenance is needed. This makes geothermal energy more reliable and attractive for investors.

Discover the possibilities of geothermal energy.

The Netherlands is a global leader in open underground energy systems, with over 3,500 Open Bodemenergie Systems (OBES). These systems store heat and cold underground for later use and are essential to the heat transition. But new innovations are needed – such as increasing storage temperatures, better integration into the subsurface, and smarter handling of seasonal fluctuations.

TNO is tackling these challenges with concrete solutions, as Maarten explains: ‘For example, high-temperature OBES (HTO) currently reach around 90°C, but we’re already exploring temperatures up to 140°C. Or smarter subsurface integration, allowing more systems to coexist in the same underground space without interference.

And through power-to-heat, we link heat storage to the electricity grid, converting surplus wind and solar energy into heat and reducing grid congestion.’ Demonstration projects like SSUSG and Joule4Joule show how entire neighbourhoods can become self-sufficient.

Read more about heat storage.

Efficient drilling techniques are key to affordable geothermal energy and heat storage. At the Rijswijk Centre for Sustainable Geo-energy (RCSG), TNO tests new innovations under realistic conditions.

One example is the DEPLOI project, where we developed the ‘steel shot drilling’ technique with Dutch drilling specialist Canopus. By creating horizontal branches, the productivity of a well can be doubled or even tripled.

We’re also exploring how existing gas wells can be repurposed for geothermal use. These innovations make the subsurface more accessible for both heat extraction and storage, lowering the threshold for the entire heat transition.