Heating our planet

42 million megajoules, that is the amount of energy the inside of our planet is conducting to the earth surface every second. If we could only capture a fourth of that energy it will be enough to cover the energy expenses of the entire world population. Despite this enormous potential, people are still unfamiliar with the concept of geothermal energy.

It is clear that we have to make the transition from a world that is based on fossil fuel to one that is based on renewables. In this new world geothermal energy could play a key role because it has some advantages compared to others sources of renewable energy. One of the biggest disadvantages of renewables is that they use a lot of surface area to produce the amount of energy that is needed. Geothermal energy also needs a lot of space but the area it occupies is in the subsurface. Another advantage of geothermal energy is that it’s not dependent on the weather. It will keep producing energy despite there is no sun and no wind. This makes it a baseload power source, which can be the backbone of the new energy mix.

Of course geothermal energy is not as favorable in in the Netherlands as it is in countries like Iceland where the steam is blowing out of the geysers. But our country still got a lot of potential. The geothermal gradient in the Netherlands is above average. For every kilometer that is drilled the temperature of the subsurface will rise with more than 30° Celsius. We also know a great deal of the subsurface because most of our geology is mapped in the search for oil and gas. We know like no other which layers have a high porosity and permeability and what the optimal spots are for geothermal wells.

We know for example that in Leiden on a substantial depth (1,5-4km). There are highly permeable sandstone layer dating back to the Triassic period (250 million – 200 million years ago). Those aquifers have such a large flow rate that lots of energy can be brought to the surface in the form of hot water. In the nearby city of Delft they already drilled four wells to a depth of 2,5 kilometer where the results are very promising (Delfts Aardwarmte Project).

The city of Leiden will also benefit greatly from the use of geothermal heat. The municipality is already making the transition to district heating. In the beginning this system will be heated by surplus heat from oil refineries and power plants of the Rotterdam harbor. But eventually this can be replaced by 100% renewable geothermal heat and Leiden will be no longer dependent on fossil fuels. Right now the city of Leiden uses 1.7 PJ (1015 joules) for domestic heating. This can already be replaced by 12 relatively shallow wells (2 km depth) of 5 MW or even less wells with a larger depth and a higher capacity.

With a fully functional district heating system powered by geothermal energy, Leiden could be the first city in the Netherlands, which is completely independent from fossil fuels for heating. Then we can proudly say: ‘Leiden gaat goed!’

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4 thoughts on “Heating our planet”

  1. Geothermal energy is a useful way of energy generation. There is a little potential around the city Leiden. According to the Quickscan Duurzaamheid gemeente Leiden, the extraction temperature is low, 60 degrees. This temperature is only useable for the heating of houses. However, the heating network of Leiden is district heating which isn’t suitable for this low-temperature regime. In this case, geothermal energy generation would be far from useable. In 2020 there is a plan to extract this heat from the Europort and use it for the heating network of Leiden which is (in my eyes) also sustainable. How could the energy which is gained from geothermal energy be used? Why do you think it is more sustainable?

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    1. Thank you Noortje for your comment. First of all the extraction temperature completely depends on the depth that is drilled. The geothermal efficient in Leiden is a bit below average (28 degrees instead of 30 degrees per kilometer) so in theory for the same temperature you only have to drill a few hundred meters deeper. In theory the potential of a geothermal well depends much more of the flow in the aquifer where the heat is extracted.

      The heat of the Europort is kind of sustainable because it is wasted in the see otherwise but it is still coming from fossil fuel based processes like refineries and coal fired power plants. If we want to abandon fossil fuels in the future we better can not be depending on them for the heating of our cities. However it is a great start which eventually can slowly be replaced by geothermal heat which also has some great potential in the Rotterdam area. It will also really help that the infrastructure is already there.

      For now low temperature heating can not be widely applied in Leiden. But for the future this would be the norm. This kind of heating is way more sustainable than high temperature heating and with the right kind of inhouse heating (floor heating and wall heating) it will be sufficient to keep your house warm. Also with a small heat pump this temperature can be raised easily another 20 degrees with a sustainable heat pump if you really want this high temperatures.

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  2. As the plans for a heat system between Leiden and Rotterdam are already being executed, I wonder how much this system will have to be adapted to run on geothermal heat. As the source of warmth currently lays in Rotterdam, will it have a negative impact on the system if the source is somewhere else along that chain? And why don’t we simply warm Rotterdam with this system? Why go all the way to Leiden?

    That being said, this would be a great way to become independable from certain fossil fueled multinationals.

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    1. First of all I would like to thank you for your comment. The plans for the heat system between the Rotterdam harbor and Leiden are not being executed yet. They did sign some kind of contract that they have the ambition to do it but unfortunately it still isn’t definite.

      The system itself would not have to adapt much because the surplus heat and the geothermal heat both have the same carrier of heat, hot water. Over time geothermal heat could replace the surplus heat from the harbour so the city would not be that dependent on fossil fuel based surplus heat.

      The reason they go all the way to Leiden is because Leiden is really in need for a new source of heat because the current heat source (a gas fired power plant) is closing down in 2020. Otherwise they have to abandon there current district heating. Also the influence of Heineken has played a huge part and almost the entire costs for the pipeline (approximately 100 million euro) between Rotterdam and Leiden is completely payed by Nuon, Heineken and warmtebedrijf Rotterdam.

      I hope this answered your questions!

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