Direct heat utilization of geothermal energy

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Aquaculture

50% increase in growth rate

Catfish, shrimp, tilapia, eels, tropical fish

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Agribusiness Applications (2)

Must consider heavy metals, fluorides, chlorides, arsenic and boron in fluid

Can produce CO2 for greenhouses to improve growth

Iceland, New Zealand

Wairakei, New Zealand

Malaysian prawns

30 tonnes per year

Selling for US$37 to 60/kg

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Tianjin, China

Peking Duck

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59oC geo.

14 kg/h 4 t/yr dried

Tomato drying - Greece

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Greenhouse in Greece

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Aquaculture examples

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Aquaculture – Example Wairakei, New Zealand – freshwater prawns

19 ponds – 0.2 to .35 ha – 1.0 to 1.2 m deep

24oC – effluent from power plant

Produces 30 tonnes/yr

Harvested after 9 months at 30 to 40/kg

Sold for US$37/kg wholesale and US$60/kg retail

90% sold to restaurant on the property

25,000 tourists/yr

Future expansion to 40 ha and will produce 400 tonnes/yr – income of US$ 6.7 million

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Refrigeration

Lithium bromide system (most common – uses water as the refrigerant)

Supplies chilled water for space and process cooling – above the freezing point

The higher temperature, the more efficient (can use geothermal fluids below 100oC – however, >115oC better for 100% efficiency)

Ammonia absorption used for refrigeration below freezing normally large capacity and require geothermal temperatures above 120oC

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Oregon Institute of Technology – chiller

89oC producing 7oC chilled water @ 38 l/s

1 MWt installed – 500 kW net

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