Direct heat utilization of geothermal energy

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Heat Pumps

Used for both heating and cooling

Heated capacity of 3 kW to 1,500 kW

27 countries

>1.300,000 units installed world-wide

Growing at the rate 20 to 30%/year

COP of 4 (75% savings in electricity)

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Heat Pumps (2)

Ground source and geothermal heat pumps (GSHP or GHP) – uses 5 to 30°C ground temperature

50 to 100% more efficient than air source, since uses constant temperature resource

Ground coupled

Horizontal in trenches 1 – 3 m deep

Vertical in 10 cm diameter 50 – 60 m deep drillholes

Others

Ground water

Using well water

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Industrial Applications

Oldest: Larderello, Italy – boric acid and borate compounds processed since 1790

New Zealand: pulp, paper and wood processing at Kawerau

Iceland: diatomaceous earth drying – Myvatn

USA: vegetable dehydration (onion) – Nevada gold extraction (heap leaching) - Nevada

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Industrial application examples

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More industrial application examples

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Food dehydration belt dryer

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Rice dryer – Macedonia

75oC resource – 35oC air – 10 t/h – 1,360 kWt

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NEW TRENDS

COMBINED HEAT AND POWER PLANTS

Low temperature resources used for binary power production and cascaded for direct use

Temperatures as low as 98oC are being used

Makes efficient use of the resources

Improves economics

See GHC Quarterly Bulletin 26/2 (June 05)

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COMBINED GEOTHERMAL HEAT AND POWER PROJECT NEUSTADT GLEWE, GERMANY

Wells drilled 1986 and 1989 – 2,300 m

Geothermal water at 98ºC – 1,700 l/s

Heat plant provides basic load for district heating network – 11 MW (thermal)

6 MW geothermal – 95% of energy

210 kWe binary power plant added meeting the electricity demands for 500 households

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