| Abstract |
The R & D efforts in the past years led to remarkable achievements in direct uses of geothermal energy in Switzerland: areal density of borehole heat exchanger systems for decentral space heating is highest worldwide; novel solutions like combined heat extraction/storage, energy piles, tunnel water use are supported by governmental aid. While a white spot on the world geothermal map in the mid 1970ëes, today it occupies the prominent world rank three in direct use. The risk guarantee system for aquifer drilling >400m which terminated in 1998 led to some success (e.g. the first doublet system in Riehen/BS which is being extended into Germany) but also to a number of failures. The heat supply from geothermal sources is via electric heat pumps (HP). In 1998 the heat production for direct applications (mainly space and domestic water heating) was 618 GWh, the geothermal input (before the HP) amounted to a total of 410 GWh. Over 90 % of this is supplied by shallow systems (horizontal coils, borehole heat exchangers (BHE), and groundwater wells. Annual growth rate is 12 %. The BHEís nowadays reach 200 m depth; drilling and installation cost is around 40 $/m. Nearly 20ë000 BHE/HP systems operate to date, mainly for single family dwellings and smaller building complexes. With one BHE/HP system every two km2 Switzerland is the world leader. Several systems operate with BHE groups, deep BHEís and in combined heating/cooling use. A substantial R & D project (ÑDeep Heat Miningì) aims at the realisation, before the year 2007, of a co-generation facility producing heat and electricity from fractured crystalline basement. Substantial basic research is conducted in parallel to investigate, within framework of the European Hot Dry Rock Program (Soultz/F), coupled thermal, hydraulic, rock mechanics, and chemical processes in fractured media. Further international activities (e.g. participation in the IEA Geothermal Implementing Agreement) are summarized. The standard Country Update reporting tables show numbers for the year 1990; it is anticipated that the geothermal production will amount to about 680 GWh in the year 2000. |