Large-scale simply means that one particular solution is used in very many places. In Denmark, heat grids are used throughout the country and in many residential areas and villages. Small-scale means little use of a particular solution. In the Netherlands, for example, here are about 17 active geothermal systems, mostly in greenhouse farming but sometimes in combination with homes to which waste heat is sold.
GGN is committed to large-scale application of geothermal heat in residential areas. The best way to do this is to limit the number of houses per heat source. The advantage is that the geothermal heat is actually used locally. Therefore, the amount of heat required from one geothermal source is limited but optimal.
The heat demand in a neighborhood is not as concentrated as that for, say, greenhouse farming. The heat demand is spread out, over a residential area. So a solution from greenhouse farming is not ideal for application in residential neighborhoods. It’s inefficient because of heat loss and a challenge when it comes to security of supply.
Denmark is already further along with the use of heat networks. The use of publicly accessible lenders who accept a 45-year amortization period and involvement of residents (with participation) is also much more established there. In Indonesia and Iceland, the use of geothermal heat is the most normal thing in the world, partly because the subsoil, due to active volcanoes, is very warm there and steam can already be extracted from relatively shallow wells to generate electricity. The steam from the earth also comes “naturally” to the earth’s surface.
Not in the Netherlands, here hot water has to be pumped up and is widely used in greenhouse farming. This has to do with the type of geothermal energy developed in the Netherlands so far.
In the Netherlands we are talking about so-called low-enthalpy heat, popularly called hot-water and not steam. Steam is called high-enthalpy heat. Steam from underground can very well be used to generate electricity as is done in a power plant.
Conventional heating with a central heating system fired by natural gas as the heat source operates at a temperature difference of 20°C. Water is heated with natural gas to 60°C with which, through the radiation from radiators, a room is heated. The return temperature is typically 40°C and therefore a supply temperature of 65°C from a heat network would be more than sufficient. This is called a middle-temperature heat network in the Netherlands. So existing homes are extremely suitable for geothermal heat of 65°C (which corresponds to a depth of 1,800m below ground level). A mid-temperature heat grid is many times cheaper than for hot water or waste heat. Saving on the cost price for consumers is thus easy to achieve.
There actually needs to be a better balance between consumer desire and “outside” supply. Currently, people still too often reason from the supplier side.
The Energy Act (2025) now gives district residents many options that are legally anchored and in which rights/obligations are guaranteed. There is now a choice to consider heat from ‘outside’ and heat ‘in-house’. So a choice between what a provider calculates for you and what residents collectively calculate themselves. This is also the choice between large-scale (local) versus small-scale from afar.
