RP:
power=generator
power_source=geothermal?
http://wiki.openstreetmap.org/wiki/Tag:power%3Dgenerator
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HB: this seems more like the resource extraction point, which is connected to a steam pipe, which travels to a generator building with a turbine/head exchanger inside. So not really accurate to use power=generator.
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tagging as bore to distinguish it from man_made=water_well.
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HB Aug 2012: checked for new dataset. tagging the same as previously uploaded V16 data for the Mainland, but there are about a dozen new ones to merge in so not calling it complete.