Why hasn't anybody tried geothermal resources for free power?

Question

I was recently watching the Discovery channel and if you go down some were em between 2 and 5 miles in the earth it start to get hot due to geothermal heat. In Russia they have drilled as far as 7 miles and there are salt mines in the U.S that have gone as far as 2 miles, they would be deepper but its to hot. Why not drill far enough down to insert or blow out a cavity to retain water and use the geothermal power to boil it and pip the steam back to a steam turbine giving us free power..

Answer 1

Geothermal energy is widely used for "free" power.

For geothermal energy to be efficient, the geothermal gradient ("Q") has to be high enough to make it economically feasible and there has to be an electrical load somewhere close by. Not every place on earth is suitable for that, and it is never free!

For example the Beowawe geothermal field in Lander County, Nevada has drill holes over 1,000 meters deep and it produces about 15 megawatts of clean electricity. Thats a value of over $10 million of renewable energy every year, just at one plant! There are plants in California that are much bigger. Geothermal power plants work by piping +100°C ground water under pressure to prevent boiling from deep wells to a turbine, and then allowing the hot water to boil or "flash" at the turbine. The steam is then condensed into water and piped back underground with injection wells to be re-heated.

Geothermal energy is also used in Italy, Iceland, Philippines, California, New Zealand, and many other places.

Ground source geothermal systems are also quite common in North American homes, and have a pay-back time of 7-10 years. Their real advantage is that they can produce cooling and heating for most homes. Again, they are not free, but it does reduce our dependency on other energy sources.

Here are some links for more info:

http://www1.eere.energy.gov/geothermal/

http://www.nevadageothermal.com/s/Home.a...

http://www.geoexchange.org/

http://www.unocal.com/geopower/index.htm...

http://www.smu.edu/geothermal/

http://www.caithnessenergy.com/geotherma...

http://www.sierrageopower.com/

To actually tap into the earth's molten mantle would require drill holes deeper than we have the technology for, and also heat resistant heat exchange equipment that we just don't have the materials for.

Answer 2

You use the term "Free power"
It is a common missconception that if the resources are available all we have to do is magically tap into them to get free power. In this life nothing is free, just as there are no perpetual machines

The problem is one of efficiencies, location, and cost.
lets start with the efficiency issue. All renewable power generation techniques have low efficiencies ranging from 3% to 21% Solar is now becomming one of the most efficient means with solar panels now reaching 30% efficiency.
This means that of all the energy that is reaching the solar panel only 30% is being converted to electricity!

It would cost to much to do what you plan and be able to recover the money spent in a timely manner. There are many losses of energy that you are not thinking of or are not aware of.
The resultant energy harnessed would, if you were lucky be 10% of the energy available.

Losses include loss of pressure from the long trip of the water up to the turbine, temperature loss, convertion loss at the turbine.
There is even transmition losses that occur when the electricity is sent over long distances.
Also don't forget that once you generate electricity it has to be used right then, there is no means of storing high voltage electricity.

Maintainance cost are also a factor. How much will it cost to replace the broken pipe that is 2 miles long?

Although many oil companies use the natural gas that is emitted from an oil field and use a turbine-generator, this is not something that has the power to be scaled up to power our homes.

Answer 3

It's not 2-5 miles for everyone. If it were alot of mines would have hit them (as you stated).

ALL of Iceland runs on it, and free heat to boot. Hot Water is sent through pipes into towns and cities where it's distributed at no cost (it runs down hill see, and there's no need for power to distribute it).

It's also hard to control in a controled manner (it makes sense, say it 10x's). Because the pressure is not constant keeping it constant when it's not can be some burden. In Iceland they grab from the runoff. In the states we call it Yellowstone and prevent anyone from ever using it for anything other than nice vacation photos.

Answer 4

As usual the bottom line is cost. "They" are working on wind power,solar power, water power [have this] and nuclear power [this one is scary.] Nothing in life is free with the exception of the intangible things - love, family,
friends while sometimes even these come with a price. So could you explain why you working on this project as a driller or pipe fitter not wanting to be paid for your work? Yours is a feasible idea, why not pitch it to someone who could do it?
The car manufactures make crossover cars yet the bottom line Joe Q. Citizen can't afford to buy them to save the ozone - go fig.

Answer 5

I heard about a large plant near San Diego. Iceland gets most of its power from geothermal. Most places aren't suitable but hopefully technology may expand the number of places where it is practical.

Answer 6

Geothermal energy is very popular in Iceland where it is readily available. The US has plenty of potential to develop it more and there are already some projects, mostly there just hasn't been a huge push to expand it, read this wiki article for more info: http://en.wikipedia.org/wiki/Geothermal_power#Disadvantages

Answer 7

it's done a lot in sweden and finland. but it's not for large consumption as far as I know. Only a few users can utilize it at one time. that makes it costly.

Answer 8

It is used, as mentioned.

And nothing is free.