Alternative Fuel >> Earth's Mantle / Lava to Create Steam?

Question

I'm sure there is a logical reason for my question but here goes.

I know for nuclear power radioactive material is used to create steam which turn turbines and generate electricity. Unfortuantely U/Pu are non-renewable resources.

Underneath the earth's crust is the mantle. Why dont engineers simply drill to this level, stick in a pipe to have the lava rise to the crust level, then use the heat to boil water to create steam. So instead of using radioactive material one is using the limitless mantle heat to do the job.

Answer 1

The first two answers are spot on. Geo-thermal energy is the energy source of the future. In Australia the first "Hot Rocks" power station is coming on line. It uses the heat from granite between 4 and 5 kilometres below the surface to provide steam to turn the generators. Other stations in the US, New Zealand and a few others use hot water from below the surface to power generators, or provide heating to city buildings.

Answer 2

As has already been said using heat from the earth is called geothermal power and is already being used. It's based on the heating of rocks much further up in the crust and the natural increase in heat at depth (not all the way down to the mantle). I disagree that it should not be classed as renewable as heat from the radioactive decay of isotopes in the core will outlast the human race by a significant period of time.

More specific to your question, drilling all the way down to the mantle is not really practical. In order to do this engineers would need to drill a 40Km+ deep borehole. The deepest one at present is the Kola borehole in Russia which is only 12Km.

the problem is that it's generation potential varies quite a lot. To produce a significant amount of energy you need areas which have been heated to an unusual temperature for their depth. This works in Iceland especially well as it's right over the mid Atlantic ridge and there are pockets throughout the world but it can't be used everywhere.

Answer 3

The first answer is correct. I would add that if you do some research on Iceland you will find that their main source of power is Geothermal energy.

Answer 4

Geothermal power is produce due to the pressures under the earth's crust.  Due to the thickness of the crust of the the pressure generates great heat.  While know the heat is available, the movements of the earth makes most of man's material weak in the present of the heat generated.  As one goes low, the inner material becomes semi- fluid to pressure.  there are locations where the molten rock moves close to the earth surface.  While much is know, more is learn every year of the effect and affect of the movement of the earth's crust.

Answer 5

They already harness the heat from the Earth to produce energy. Its known as geothermal power. And although you would think that the heat from the center of the Earth is renewable, it is not. Our core remains molten because of the radioactive decay of elements. So in a way, it is like a nuclear reactor.