About Transmark-EDS
Geothermal Energy w Heat
Geothermal energy use the heat from the earth to heat houses, offices or greenhouses. Extracting the heat from the ground involves using the hot water that is stored in water-bearing layers in the subsoil, at depths at which the temperature is high enough to use either directly or indirectly (by means of a heat pump). These water-bearing layers are present in the subsoil in large areas of the Netherlands. Soil heat pumps and hot/cold storage are already widely used and a very normal phenomenon in the Netherlands. The same does not apply to deep geothermics. At depths of around 1.8 kilometres and more below the earth’s surface, the water-bearing layers in our region are hot enough to produce water at 70°C or more – sufficient to use for tap water supplies (without any risk of Legionella bacteria) and to heat homes or greenhouses. From depths of around 3 kilometres and more, the temperature is sufficient for the production of electricity as well. In fact, the earth’s temperature increases by around 3 degrees per hundred metres as a consequence of radiation from the earth's core.
Costs and economics
The consequence of this is that using geothermal energy is a capital-intensive option. Drilling wells is expensive (from around 1 million euros per kilometre) and a doublet easily costs 5 million euros. Such work is only economically viable if large quantities of hot water can be produced and sold. For a geothermic installation to be cost-effective it is, therefore, essential that there is also enough flow in the water-bearing layers to allow the required quantity of connate water to be produced. A quantity of 100 m3 per hour is often the minimum requirement. This again implies that the production of heat has to be substantial and preferably concentrated (from around 1500 homes or 3 hectares of greenhouses).
Why geothermics
Geothermal heat produces none or hardly any CO2 emissions and geothermics is also one of the more cost-effective sustainable energy options. Comparative studies have repeatedly shown that the costs of avoided CO2 are almost lower than alternatives - if the right conditions exist as regards geology and demand for heat. The increase in fossil fuel prices means geothermics is already competitive with natural gas in favourable circumstances. Important operational aspects are the high reliability and controllability of the heat supply which, in addition, is also entirely independent of external conditions. Once the wells have been drilled, the source does not take up much space at all and therefore does not create any nuisance for the environment.
Development phase
In the Netherlands, deep geothermal projects are still in its initial development phase. In recent years, wells have been drilled in Heerlen to a depth of 800 metres (the old mine shafts) and the first deep geothermic doublet was installed in Bleiswijk in the summer of 2007 (at the horticultural company A + G van den Bosch). This contrasts starkly with – for example – Germany where between 30 and 40 large-scale projects have been implemented in comparable geologic conditions and where the oldest installations have already been operating for decades.
Perspectives
Geothermics has the potential to meet a large proportion of the demand for heat in the Netherlands. It has been calculated that there is more geothermal heat in Dutch subsoil than gas, oil and coal. There are not that many energy sources which do not cause nuisance or CO2 emissions and which are also independent of external factors.
More information can be found at: Platform Geothermics.
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