In order to achieve its climate targets, Germany needs to convert its heat supply as well as its electricity supply to CO₂-free energy sources. Many homeowners are therefore looking for alternatives to fossil gas or oil heating. The tapping of near-surface geothermal energy is technically proven, but often not yet the first choice when installing a new heating system. To simplify the use of geothermal energy for heating, hot water and air conditioning, researchers at Fraunhofer IEE are working with other partners in the UrbanGroundHeat project to develop handbooks, planning methods and implementation standards. In the process, model calculations are used to map the previous experience of industry, research, legal experts and utilities.

"The heat transition is a core element on the path to a climate-neutral Germany. So far, CO₂-free heating technologies have mainly been used in new buildings. Yet the potential is huge: up to 75 percent of our country's space heating and hot water requirements could be met by geothermal heat pumps. However, in order to supply the existing buildings in our cities with heat from geothermal energy, a number of challenges must be overcome," says project manager Dietrich Schmidt, Fraunhofer IEE, explaining the objectives of UrbanGroundHeat.

UrbanGroundHeat is funded by the German Federal Ministry of Economics and Climate Protection with about 2 million euros. Around 700,000 euros are additionally contributed by partners from the industry. Industrial partners are Stadtwerke SH, Trianel, GASAG Solution Plus, Stadtwerke Solingen and GGEW Bergstraße. The work of the research organizations ISFH, Stiftung Umweltenergierecht and the Fraunhofer Institutes IEG and IEE is also supported by Stadtwerke Münster and Ahlen. Organizations and political institutions are also involved in the research.

The project started on January 1, 2023, and will run for three years. The work complements Fraunhofer IEE's EQ-City neighborhood assessment tool by adding the aspect of geothermal coverage of heat demand. More specifically, UrbanGroundHeat is investigating the technical use of geothermal brine-to-water heat pumps and heat pumps in conjunction with well systems, wastewater and waste heat utilization through local heating systems for use in existing urban neighborhoods, taking into account geological and regulatory constraints. The case studies are analyzed with the help of simulation calculations, which form the foundation for the development of concepts for a conversion of the heat supply.  

Kick-off meeting of the project partners in Kassel in mid-February 2023

The kick-off meeting of all project partners took place in Kassel in mid-February 2023. The plan of the researchers now envisages building models that map the technical, regulatory and economic requirements for a geothermal heat supply in urban neighborhoods. Planning tools and handbooks will be used to facilitate extensive conversion from current fossil-fuel heat supplies.

Over the next three years, the scientists will work on various sub-goals. The first step involves recording and mapping existing neighborhoods in the assessment tools. This includes the building structure, geothermal possibilities, storage options and regulatory constraints. In the second step, concepts and feasibility studies are developed for two sample neighborhoods.

The neighborhood projects under consideration are located in Solingen in North Rhine-Westphalia and Bensheim an der Bergstrasse in Hesse. "The settlements we are looking at with UrbanGroundHeat are typical of urban areas: a large proportion of Germans currently live in multi-story apartments and small one- or two-family houses. We want to use geothermal energy to provide these people with an alternative to fossil fuels for heating and hot water as well as for air conditioning in summer," says Schmidt.

In a third step, these findings will be generalized. The scientists' goal is to offer local communities and energy suppliers the results in the form of checklists and a toolbox for the development of further projects. In addition, the research team will accompany the implementation: The experiences of users and stakeholders will be recorded and evaluated in workshops.

National and international networking to promote geothermal energy

To avoid acting only on a small scale, a systematic analysis of the example properties, the establishment of a monitoring group and the connection to global activities of the International Energy Agency (IEA) will bring near-surface geothermal energy more into the public focus. Schmidt: "Close cooperation between research and industry means that the experience gained from UrbanGroundHeat will be available to a very wide range of users. In addition, results are transferable to many urban neighborhoods in Germany. This gives energy providers and communities a valid assessment of which geothermal projects can be developed with priority in their service area."