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Energy from the earth: geothermal district heat

I’ve seen several news stories on geothermal technology district heating schemes in the last few weeks. Last month, a new geothermal plant was opened to supply heat from deep underground to an Audi factory in Gyor, Hungary, plus to 2,500 local homes and other industrial customers. At 55 MWth this is a sizeable plant.

Then, just last week Mitsubishi Heavy Industries’ Turboden subsidiary announced completion of its latest, ORC turbogenerator installation ” at a 100 MWth geothermal district heating plant in Turkey. The 3 MWth turbogenerator will be used to produce electrical power from the low enthalpy geothermal source. Turboden says that its geothermal fleet amounts to nine plants located in Turkey, Europe and Japan, with a total generating capacity of 31 MWe.

Last the UK’s Eden project, has recently announced plans to add a rather smaller, 3″4 MW, geothermal heat and power project to its environmental demonstration complex in Cornwall.

So, is geothermal district heating more common than I thought? In the UK I had only ever come across the Southampton DH scheme ” this has been operating for 20 years or more and includes a geothermal component alongside gas-fuelled generation. However, currently there are plans to develop new schemes in Manchester and Newcastle ” as well as in several European countries.

A report issued last year by the GeoDH project reports that there are already more than 200 geothermal district heating systems in Europe, with much of the capacity located in Hungary, Poland, Slovakia, Slovenia, the Czech Republic, and Romania. Several countries of Western Europe have targets to expand their use of the technology, with Germany, France and Italy the most ambitious, says GeoDH. And the Netherlands, Ireland and Denmark are all looking to develop their first systems.

France ” where the Greater Paris region already boasts several geothermal systems ” is indeed one of the more ambitious countries. French utility Engie is said to be developing around 50 MW of new geothermal projects there, to bring the company’s total geothermal capacity to 100 MW.

Geothermal energy may never be a major source of heat for district heating systems but, where the resource is available and reachable, it makes good sense to exploit it.