Great potential for large-scale heat storage in Denmark

25 July 2018

The Danish subsoil holds large amounts of hot water, and the water reservoirs can both provide heating for the Danish citizens and store energy from wind turbines, when wind production is high.

During the summer, excess heat is pumped into a water reservoir. During the winter, the heat is pumped up again, typically to be used in a district heating system. Once utilised and cooled down, the water is then pumped back into the water reservoir, where it is again heated throughout the summer. This process can be continued year after year.

In combination with the heat pumps, it is expected that the geothermal heat production can provide heat for around 500,000 Danish households.

Commercial interest in geothermal energy

“Almost half of the energy consumption in district heating today comes from coal and natural gas. Those types of energy have a clear expiration date, but it is important that the new green energy solutions that replace them simultaneously support the development of an intelligent energy system, where it is e.g. possible to save the fluctuating energy production we receive from wind and sun. In this case, geothermal energy and heat pumps have a special role to play’’, said Lars Van Hauen, Chief Innovation Officer in E.On.

He points out that E.On in Malmø, Sweden, is about to implement one of the world’s largest heat pump projects of 40 MW, and that the energy company will research the opportunities for a large-scale geothermal heat storage in Denmark.

The Danish Minister of Energy, Utilities and Climate, Lars Christian Lilleholt, is pleased with this interest to invest and would like to see a bigger commercial use of geothermal energy.

‘’One of the most important questions in the green transition is, how we can store the surplus sustainable energy in the smartest way in order to use it when it is needed’’, said the Minister.

Energy storage with minimal heat loss

In cooperation with several Danish universities, the geothermal operating company, GEOOP, has contributed to different research projects within geothermal energy. According to Lars Andersen, Executive Director in GEOOP, the geothermal water reservoirs can be used for energy storage. Consequently, they become the next important step towards a stable and green energy system.

‘’As opposed to other types of energy storage, the heat loss in these heat-storages are minimum. In the long term, the heat loss during a season will be 15 percent, which can contribute to keeping the heat prices low’’, said Lars Andersen.

Even though Danish companies have great experience in drilling for oil in the Northern Sea, geothermal drilling on land demands other drill tools and skills. Innovation Fund Denmark’s research project Geotherm, which GEOOP participates in, aims to increase knowledge about the possibilities of the underground and make it easier for commercial companies to utilise underground heating

Together with Iceland Drilling Company and a number of experts within geology, reservoirs and drilling, the energy company E.On have teamed up with GEOOP to uncover the business potential of geothermal energy in a number of Danish cities.

Source: Energy Supply (in Danish)