In Norway geothermal heating is most common as geothermal wells in bedrock. Such geothermal wells exploit heat from the bedrock and groundwater using a heat pump system. The short distance to the bedrock in many parts of the country make it easy to extract such heating or cooling.

The challenge is that more than 25 per cent of built-up areas in Norway have 30 metres or more of deposits above the bedrock. Such a great distance to the bedrock entails high costs when establishing geothermal heating systems with geothermal wells in bedrock. The distance can also pose challenges for operation of the facility.

“We recognise that there is a need for research on stable and reliable energy sources in urban areas. In parts of Trondheim and Oslo there are areas with a lot of deposits, such as clay and silt, that can make it difficult and costly to reach the bedrock to extract the energy in the normal manner. With new technology, we are going to change this,” says project manager Sondre Gjengedal with NGI.

“Energy piles” a part of the structure of new buildings

In the project ‘Sustainable energy from deposits (SEFD),’ Malvik municipality will test and adapt a new solution for storage and extraction of energy using pile constructions in deposits. The solution is called ‘energy piles.’

“In SEFD we will test how ordinary pile constructions can be designed for such purposes. The tests will be carried out as a pilot project at the Saksvik treatment plant in Malvik,” Gjengedal says.

The project is funded by the Trøndelag Regional Research Fund (RFF) and is a partnership between Malvik municipality and the Saksvik treatment plant, and the project partners NGI, Fundamentering AS, Noranergy AS and Winns AS.

“In time, the goal is to implement energy piles as a part of the foundation solution for new builds where pile foundations are required due to thick deposits. By integrating energy solutions in the piles, we may be able to drastically reduce the installation costs for energy systems, and that would be yet another step in the right direction towards a smart and sustainable building,” says project supervisor Tom André Havnes with Malvik municipality.

Challenging Nordic climate

Energy piles in deposits have to an increasing extent been used in southern Europe in the last decade. The most common method of implementing this is to integrate a loop of collector pipes in concrete piles.

“Unfortunately, our ever-changing Norwegian climate poses certain challenges in terms of the possible energy utilisation for such energy piles in this country. It’s important that the system works optimally when we combine the piles with the foundation solutions,” says Wilhelm Huus-Hansen with Noranergy AS.

The tests being carried out in this project will also entail that the energy piles will be adapted to the Nordic climate and Norwegian building practices.

“We hope and believe that a new and adapted design will increase the possibility for energy utilisation, energy storage and efficiency. At the same time we must ensure that the energy piles ensure stable foundations,” Gjengedal says.

Increased growth of sustainable and energy efficient buildings

For Trøndelag, increased use of geothermal heating will be a local initiative for development towards a more sustainable society. At the same time, this will be a step in the right direction towards contributing to achieving the UN and EU goals for sustainable and energy-efficient buildings.

“Malvik municipality has several projects in the pipeline that may be suitable for energy piles, so we are hoping for good results,” Havnes says.

To develop expertise with regard to the optimal design and use of energy piles, pilot projects are needed, such as the SEFD project.

“The goal is that the construction industry can use energy piles in areas with thick deposits, both domestically and internationally. This will lead to more sustainable cities and local communities,” Gjengedal concludes.

The Norwegian Geotechnical Institute (NGI) is a leading international centre for research and consulting within the geosciences. NGI develops optimum solutions for society, and offers expertise on the behaviour of soil, rock and snow and their interaction with the natural and built environment. NGI works within the markets Offshore energy; Building, construction and transportation; Natural hazards, and Environmental Engineering. NGI is a private foundation with office and laboratory in Oslo, branch office in Trondheim, and daughter companies in Houston, Texas, USA, and Perth, Western Australia. NGI was established in 1953.