Well most ppl thing this is a clean energy, but i'm skeptical about it. What we are doing here is that we are using the heat from the depth of the earth to cool our water for powerplants. If we build thousands of those to use this energy, wouldn't we be cooling our planet? cause otherwise those geothermal sources would be locked by thousands of tons of materials, but we are using fast cooling methods, u may say that its a small percentage and won't affect it! but thats what we used to say about polluting the earth and sea and oceans.....and a lof of other matters.