I've been recently reading and learning about geothermal powerplants and one thing on wikipedia (which might be wrong, but usually isn't) bugs me alot. It says:
Direct geothermal heating systems contain pumps and compressors, which may consume energy from a polluting source. This parasitic load is normally a fraction of the heat output, so it is always less polluting than electric heating. However, if the electricity is produced by burning fossil fuels, then the net emissions of geothermal heating may be comparable to directly burning the fuel for heat. For example, a geothermal heat pump powered by electricity from a combined cycle natural gas plant would produce about as much pollution as a natural gas condensing furnace of the same size. Therefore, the environmental value of direct geothermal heating applications is highly dependent on the emissions intensity of the neighboring electric grid.
Why would a geothermal power plant EVER use any other energy than the one it produces. If it's a power plant generating energy than it's output energy must be higher than input energy. That means, that it could always use it's own electricity + leave some to provide. Assuming environmental concern exists, why would you ever import an energy from a CO2 emitting source to power a power plant, instead of using a fraction of the one you produce? "is highly dependent on the emissions intensity of the neighboring electric grid" - that makes no sense. Why should the power plant executive even consider importing energy from a neighbouring grid when they can ALWAYS have their own (probably without an fee, since it's their own). Assuming the power plant managers care about CO2 emmissions, but if they didn't, then it wouldn't make sense to have one instead of a coal plant (simpler and more cost-effective).