“Working on renewable energy? Mind the heat!”

The German International Geothermal Office aims to enhance possibilities for geothermal energy and – by doing so – to help make extensive use of German experience in this field. Dr. Claus Heske is the director of this office. He sends a clear message to the world: “Do not forget the heat! Sustainable power production may seem interesting, but heat is going to be extremely important as well.”

“Geothermal energy is very successful in Germany and I see two important reasons for that.  The first one is the EEG energy law. This law makes it possible to find funding for (electric) power. Having this funding makes it a lot easier to build a solid business case. You can imagine drilling kilometres into the soil is expensive, and convincing banks to invest in a slowly growing revenue portion of heat, is difficult. The funding of power makes a detailed calculation possible, showing banks when they’ll get back their investment.”

“The second reason has to do with switching the aim of a plant. Geothermal energy can be used to  produce power, and to produce heat. Both require different plant setups. If you want to produce heat, you need a district heating grid that will use the heat, and building this is expensive and a little uncertain.  This uncertainty will not attract investors. However, when we start a plant with the aim to make power, which can be calculated, the business case is easier. Then – we can use the money from the power and bank loans for building a heat grid. And then, over time, when the district heat grid expands,  move to operations to produce primarily heat in winter and power in summer.”

And most heating grids require a different temperature as well, don’t they?

“They do. For power production, you will need temperatures of more than 90 degrees Centigrade. District heating will need ‘only’ 50 or 60.  So when you start with power production, the ‘waste’ heat still can be used for heating homes or workspaces.”

“In Germany, most geothermal plants are selling heat. They switched their aim from ‘power production’ to combined ‘heat and power production’. And they are earning money with that now.”

In this article, we are mostly discussing deep geothermal energy – where you pump up very high temperature liquid, then extract the heat and re-inject the liquid in the depth. Deep geothermal energy is used for providing residential areas or cities with heat and/or power.  A a contrast, shallow geothermal energy systems have a closed circuit and less deep drilling. This technique is for providing single buildings or small groups of houses with heating and/or cooling.

What makes geothermal energy so extremely sustainable?

“One can use your own power for the pumping. You do not need any CO2 for either heat or power. Of course, drilling three to five kilometres deep is difficult, but we have growing experience in that. And from every new attempt we learn. And there is no reason to fear that we will cool down the planet by our use of geothermal heat, ever. So it is completely renewable and CO2-free.”

How do you evaluate the current heating grids in the Netherlands?

“As far as I know the most dutch deep geothermal systems now have too low temperatures to produce  power. Heat for agriculture already is a good business plan. But if you want to win power and heat, you must drill deaper. Get higher temperatures, and win power. And use the ‘waste’ heat for heating purposes.”

“In the Netherlands, there are a lot of people living in short distances from one another. A lot of houses with very small distances between them make a local heating grid much cheaper.”

Your work is to connect German knowledge and experience with parties in other countries. How big is the opportunity for the Netherlands, in your opinion?

“As we saw before, it is one hundred per cent renewable. It can be used to win power, and for heating. Keep in mind we will all be forced to change our heating systems for a more sustainable technique. In Germany everybody is talking about sustainable power. Now they say: ‘we’ll need sustainable heat as well’. Geothermal energy can provide this heat. Day and night. When there is no sun, solar panels give no power. A similar story goes for wind. There are issues storing power. Heat can be stored. So my main message for all people in the Netherlands, working with renewable energy sources, is: ‘do not forget the heat!’”

So, then. Who should take the lead?

“In Germany, the geothermal heat production has been mostly started by municipalities. They have the clients, they can build the heating grid. They have the experienced staff. Of course, there is a lot of money concerned. But the point when investments are regained sometimes comes years before the point calculated before. And then one starts making money with it. In the South of Holland several doublets are already drilled for greenhouses (Poeldijk, De Lier, Kwintsheul, Pijnacker). This means the regional geological conditions are fairly well known by now. This information should be used to make the existing heating grids in The Hague and Rotterdam more sustainable and to enlarge them. Gas will be phased out, after all….”

Nationaal Warmte Congres

Meer weten van of over Dr. Claus Heske? Tijdens het Nationaal Warmte Congres gaat hij o.a. in op ‘Geothermie, hoe duurzaam wilt u het hebben’?

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