of Southampton at the last census was 217 445, so the geothermal power
being delivered there is 0.13kWh/d per person in Southampton.
97The heat flow at the surface is 50 mW/m2. Massachusetts Institute of Technology
(2006) says 59 mW/m2 average, with a range, in the USA, from 25 mW
to 150 mW. Shepherd (2003) gives 63 mW/m2.
98“Generation of electrical power from hot dry rock was unlikely to be technically
or commercially viable in the UK”. Source: MacDonald et al. (1992). See
also Richards et al. (1994).
–The biggest estimate of the hot dry rock resource in the UK ... could conceivably
contribute 1.1 kWh per day per person of electricity for about 800 years.
Source: MacDonald et al. (1992).
–Other places in the world have more promising hot dry rocks. There’s a good
study (Massachusetts Institute of Technology, 2006) describing the USA’s
hot dry rock resource. Another more speculative approach, researched by
Sandia National Laboratories in the 1970s, is to drill all the way down to
magma at temperatures of 600–1300 °C, perhaps 15 km deep, and get power
there. The website www.magma-power.com reckons that the heat in pools of
magma under the US would cover US energy consumption for 500 or 5000
years, and that it could be extracted economically.
–Southampton Geothermal District Heating Scheme. www.southampton.gov.uk.