Low Carbon Power Generation
in Copenhagen
Geothermal power in Copenhagen
There are two geothermal power plants in Denmark. The first-opened
is at Thisted on the north west side of the Jutland peninsula. The second is in Copenhagen, on the harbour within sight of the city centre. Energy experts predict that Copenhagen could power half its
district heating from geothermal sources for centuries to come.
Both plants are are run by consortia that include
DONG Energy as the majority stakeholder. Thisted was built 1981-84 (enlarged in 2000). The
Amager plant in Copenhagen was begun in 2001 and its first geothermal energy was produced in November 2004. A third plant is planned for Sønderborg in 2012, with another in Copenhagen around 2015 and more anticipated on the Jutland peninsula.
The principle at work is to use the Earth's naturally percolated and heated water resources to either power turbines or run heating (or cooling) systems directly. Below a surprisingly shallow depth (a few metres), the temperature of the Earth is stable. But drilling deeply gets you into rising temperatures, since the Earth gets hotter as you get nearer to its core. Generally, it rises 20-30° C per km — more if you happen to be near a volcano.
Water trapped underground in aquifers heats up naturally and the hot fluid is extracted by drilling into porous rock. This fluid is used to heat the supply pipes in district heating schemes, or it is flash-heated into steam and used to power electricity generators such as those at the Amager plant (see box at right).
Geothermal energy is clean and sustainable, though some external power — usually about 10% — is used to transfer the heat from the boreholes to district heating supply pipes. Spent (cool) liquid from the process can be returned to the aquifer for reheating through a second borehole, maintaining the pressure underground.
Copenhagen's Amager plant is in the same locality as the city's largest
district heating network and
combined heat and power (CHP) plant, and produces 14MW from its two wells. It's adjacent to a major geological fault line (through which water percolates to the aquifers). The water from its wells is more saline and has a higher concentration of CO2 than the water from Thisted.
The planned new plant in Copenhagen will have up to six times the capacity of Amager and could cost around one billion Kroner. The major investment of any geothermal scheme is in the drilling of its very deep wells. Seismic surveys are used to identify suitable sites.
Geothermal energy is one element of
Heat Plan Denmark, an integrated study of heating methods that includes information about reductions in CO2 emissions since 1980. It also outlines ideas for achieving the aim of cost effective and (almost) carbon neutral heating in Denmark by 2030 .....
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Top links
Aarhus University, Faculty of Science http://science.au.dk
Information about Amager and Thisted (in news story)
Danish Energy Agency www.ens.dk
Energy statistics and info on different kinds of power generation, incl geothermal
DONG Energy www.dongenergy.com
Predominantly state-owned power generation company, part-owner Amager
Energy Map www.ens.dk
Details of energy- and climate-related technologies to reduce CO2 emissions, incl geothermal
Geothermal Energy Association www.geo-energy.org
American trade association for geothermal energy in the USA and worldwide
Heat Plan Denmark www.energymap.dk
Research and development study of the entire Danish heating sector
Hot|Cool Journal www.e-pages.dk
Article : Geothermal Energy - the Future Heating Source?