Do we currently have the capacity to drill into the earth’s mantle?

Question

How far down does a hole need to go to reach a hot molten area? (I do realize it may depend on where you start digging.)

I have previously heard that it gets very hot in the lower levels of mines. Is this due to the fact that they are approaching the bottom of the crust and the magna areas? What is the outlook on using this heat energy and a renewable energy source?

Sorry this is really four questions in one.

Answer 1

No we cannot drill that deeply. Thickness of crust varies from ~ 9 km to ~ 35 km..

The geothermal gradient is ~ 25 degrees Celsius/km depth, which is why deep mines are warm (also how organic material is "cooked" into hydrocarbons or oil/gas).

There currently exist a means to tap the constancy of temperature in the shallow soils to produce heating and cooling for homes merely by circulating water in coils.

Drilling deep holes has many problems: 1) borehole deformation; 2) cost; 3) variability of materials encountered; 4) heat. And even if you could drill into the magma,rapid pressure release would problem have drastic negative consequences...

Answer 2

from this site....

http://hypertextbook.com/facts/2003/YefimCavalier.shtml

Several types of mines can be found around the world. Mines that might be considered the world's deepest are either open-pit or vertical shaft mines. Vertical shaft mines hold the record for being the deepest mines in the world. Most are located in South Africa due to its abundance of diamond and gold deposits. As of 2003 the deepest mine is the East Rand mine at 3585 meters, but as technology improves and the search for natural resources continues many mines are constantly being deepened. In the next few years, the Western Deep mine will reach 5 km.

Many problems arise when digging so deep into the Earth. The most obvious is the heat. For example, at 5 km the temperature reaches 70 degrees Celsius (158 F) and therefore massive cooling equipment is needed to allow workers to survive at such depths. Another problem is the weight of the rock. For example, at 3.5 km the pressure of rocks above you is 9,500 tones per meter squared, or about 920 times normal atmospheric pressure. When rock is removed through mining this pressure triples in the surrounding rock. This effect coupled with the cooling of the rock causes a phenomenon known as rock bursts, which accounts for many of the 250 deaths in South African mines every year.

Yefim Cavalier -- 2003


the problem as I see it , with drilling deeper than the crust is what happens when the magma senses an opening to vent out of?... you couldn't control that.........it is under pressure down there, isn't it?...

Answer 3

No. According to Wikipedia "The Kola Superdeep Borehole on the Kola peninsula of Russia reached 12.262 km (~7.62 mi) and is the deepest penetration of the Earth's solid surface. We have drilled down 1.7 km (~1 mi) into the seafloor. Because the continental crust is about 45 km thick on average, whereas oceanic crust is 6-7 km thick, we have penetrated only the upper 25% of both crusts."