Geothermal energy - from potential plays to successful growth

In the last decade and a half the Netherlands has seen a significant increase in the application of geothermal energy production. The most prolific geothermal reservoirs are Lower Cretaceous-Upper Jurassic fluvial sandstones of the Delft Sandstone Member in the West Netherlands Basin and the Permian predominantly eolian and fluvial Slochteren Formation in the northern half of the country. Runners-up are reservoirs of the Triassic terrestrial Main Buntsandstein Subgroup and the Lower Cretaceous marine Vlieland Sandstone Formation. The Carboniferous Limestone Group was the target reservoir for two geothermal systems in the Roer Valley Graben. The heat produced is primarily used in the horticultural sector, which has played a pivotal role in the initiation and first development of geothermal energy in the Netherlands. Developing geothermal energy is a complex multi-issue exercise that involves numerous surface and subsurface uncertainties. The matching of heat supply to demand is just one of the surface uncertainties. Main uncertainties from the subsurface geological point of view are reservoir quality and potential for seismicity, while main points of attention from an operational point of view are well integrity, productivity and injectivity maintenance and scaling. Geothermal development has been aided by various financial and other supportive governmental measures. The sector is maturing by integrating experience, (well) design standards, seismicity protocols, innovations and lessons learnt in multistakeholder networks. These include operators, service industry, national and local governments, academia and research/knowledge-institutes and -centres. The initial focus on the horticultural sector has widened to include district heating and light industry applications. Additionally, the single system operator model has evolved into a portfolio operator model. The aim of all this is to achieve the ambitious target of supplying a large part of the Dutch heat demand with geothermal heat by 2050.