Extraction techniques hot dry rock

Sources of 'hot dry rock' (HDR) are much more abundant than are hydrothermal regions: temperatures of 200 cC are accessible under a significant proportion of the world's landmass. This has motivated considerable research in the USA and Europe on techniques to harness this heat for electricity power generation. One result has been the recognition that few basement rocks are completely dry, but there are many regions where utilisation of their geothermal heat requires 'enhanced geothermal systems', in which reinjection is necessary to maintain commercial production.

In the 1980s, the research group at Los Alamos Scientific Laboratory, USA pioneered methods of fracturing the rock with pressurised cold water around the end of the injection borehole (Figure 15.6). After the initial fracturing, water was pumped down the injection bore to percolate through the hot rock at depths of ~5 km and temperatures ~250 cC before returning through shallower return pipes. Using such methods, complex arrays of injection and return boreholes might, in principle, enable gigawatt supplies of heat to be obtained. However, the technical difficulties and large costs have meant that only a few pilot plants, including a European joint venture at Soultz in the upper Rhine Valley, have exploited HDR. Despite these efforts, by 2004 there was still no commercial power station based on HDR.

Natural Power

Natural Power

Mantle magna

Figure 15.5 Schematic diagram, not to scale, of hydrothermal power stations in a hyperthermal region, e.g. the Geysers geothermal field, California.

Mantle magna

Figure 15.5 Schematic diagram, not to scale, of hydrothermal power stations in a hyperthermal region, e.g. the Geysers geothermal field, California.

Los Alamos Hot Dry Rock
Figure 15.6 Schematic diagram of heat extraction from a hot dry rock system.
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Responses

  • eric smith
    How to make a diagram of hyperthermal energy?
    6 years ago

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