In a traditional geothermal system, hot formation water in aquifers (so-called ‘reservoirs’) is used to extract heat from the subsurface (direct applications). The hot water is pumped up through a production well, passes over a heat exchanger and is commonly injected back into the original reservoir via an injection well. The table above provides an overview of all possible direct geothermal applications in function of the available temperature level. Geothermal energy can be used in all domains: residential, public, industry, agriculture and horticulture.
Shallow geothermal systems that invoke a heat pump are often suitable when heating individual buildings. A heat pump can also be used to meet the cooling demand for such buildings.
VITO has developed various technologies in the field of shallow (low temperature) geothermal applications. In order to implement these research results as effectively as possible, the spin-off Terra Energy established in 2009.
Geothermal energy can also be used to produce electricity or higher-grade heat. The former can be done using steam-driven turbines if the temperature and volume of produced water are high enough (T > 180 °C). However, it is also possible to generate electricity at lower temperatures (90 to 180 °C) by implementing an organic liquid or mixture of liquids in a secondary circuit, which generates sufficient vapour pressure at lower temperatures. VITO is currently performing research on the optimisation of this technology.