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Germany well positioned to utilise geothermal energy for transition of heating sector

Maps with geothermal resources in Germany (left from 60°C, right from 100°C) (source: LIAG)
Alexander Richter 14 Jun 2018

In a position paper, the Leibniz-Institut für Angewandte Geophysik (LIAG), highlights the important role geothermal energy could play in the transition of Germany's heating sector until 2050. It describes it as irresponsible to neglect the potential for geothermal heating, both on economic and ecological grounds.

As part of a recent statement released by German’s Geothermal Association (BVG), a document has been highlighted that was released already in April 2018.

The position paper on the role of geothermal energy in the transformation of Germany’s heating sector by the Leibniz-Institut für Angewandte Geophysik in Hannover/ Germany (“Positionspapier – Die Rolle der tiefen Geothermie bei der Wärmewende”), describes how Germany could manage to derive 60% of its heating supply from renewable energy sources until 2050.

In Germany it is talked about “deep geothermal” (tiefe Geothermie) to differentiate from shallow geothermal applications (heat pumps).

Based on statistical data, the authors examined how high the proportion of deep geothermal energy could be for Germany’s heat consumption in the year 2050 and whether thereby the German climate targets in the heat sector are reachable.

For the scenario of “60% Renewable Heat” a number of detailed questions need  to be answered. The most important one is how the the total heat consumption will develop. In the next step, it must be clarified which expansion targets for the use of deep geothermal energy are realistic. In the third step, the future development of the other regenerative heat sources are estimated, in order to assess which technologies in addition to the deep geothermal energy require increased funding.

What role could deep geothermal energy play in 2050?

So far, deep geothermal energy is still relatively little used in Germany, while it offers great potential for expansion. Unlike other renewable energy sources, in the case of deep geothermal development, each project needs to be planned individually, because the geological conditions in the underground can be very different. That is why it is important to intensify research and exploration of thermal utilization of the deep subsurface resources and that development is accompanied by scientific work.

The differences in the heat output can be very large and that’s why one cannot exactly predict the outcome of geothermal projects, so the report. While the temperature of a geothermal reservoir is predictable, the achievable utilisation rate is often associated with great uncertainty.

The experience from many geothermal projects has shown that on average higher energy yields per doublet can be expected in southern Germany, than in northern Germany per doublet. However, it is important to note that the geothermal systems in northern Germany were developed several decades ago without modern directional drilling technology. So it could well be that future geothermal projects show slightly higher performance in northern Germany.

For the estimation of the future development of geothermal heat utilization, the authors describe an average installed geothermal power of all facilities for district heating and building heating with production rates of >10 l / s in northern and southern Germany.  An average geothermal heating plant has two deep wells with a total length of 5.1 km. Based on statistical average estimates, the authors estimate that about 2.4 GWh in northern Germany and about  7.4 GWh in southern Germany can be achieved per year and drilled kilometer can be achieved, assuming 3,000 full-time hours.

Decisive for the future development of deep geothermal energy is therefore also the period in which the existing geothermal resources and reserves can be tapped. This one will
significantly determined by the number of kilometers drilled per year. Here is worth a look into the past. In the 1950s, the number of deep wells drilled in West Germany in just a few years increased enormously each year as a result of crude oil and natural gas production.

Looking at what pace and effort deep drilling was conducted for exploration and production of hydrocarbons in Germany, it can be assumed that a multiplication of geothermal energy production over the next 30 years, provided that the right conditions are created is more than feasible. In 1959,  deep wells were drilled with a total length of about 790 km. If one were to achieve the same for geothermal projects today, there is a possibility that about 140 geothermal heating plants could be built each year. This would include already a deduction, estimating a 10% of unsuccessful drilling campaigns. Although geothermal wells are drilled with a diameter slightly larger than oil or gas wells, 60 years of progress in deep drilling technology were not taken into account in the analysis.

An increase in drilling activity for geothermal projects to the level of the hydrocarbon industry from 1959 in comparable time would mean an annual increase of 3.5 TWh, whereby the share for southern Germany would be about three times as high as that of northern Germany.  Within 30 years, about 104.5 TWh of heat from the deep geothermal resources would be available for heating each year, for hot water or as process heat.

A recent study from 2018 by the UBA (Umwelt Bundesamt/ Federal Environmental Agency) overlayed maps of geothermal resources with setlmenent maps and natural and water protected areas, as well as national parks deducted. Based on that, there would be sufficient geothermal resources for heating for buildings and district heating in Northern Germany of about 158 TWh and about 121 TWh per year in southern Germany availble for a sustainable heat supply, more than double of the described expansion scenario for 2050.

The report estimates a potential of geothermal heating providing up to 17% of the heating supply in Germany, based on fossile energy still representing 40% of heating supply in 2050 and biomass providing up to 22%.

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Pictures above: Maps with geothermal resources in Germany. Top – left from 40°C, right from 60°C, below – left from 60°C, right from 100°C (source: LIAG)

The report highlights additional advantages of geothermal energy use for the heating sector and its potential role as third largest heating source in the national heating mix. Therefore neglecting the potential of geothermal energy for heating would have severe economic and ecological consequences.

For the full details see the original document, available  here (in German, pdf)

Source: Leibniz-Institut für Angewandte Geophysik, Hannover