Potential electricity production from water passed through Magma.

[Iou]

Dear Physicists

I am well aware that this question does not have all the necessary information on order to get an exact answer, but what I am hoping to find is some educated guesses backed by some math.

Lets imagine a 50 MT Pot filled with magma that is 700 C hot. Let’s imagine a thin pipe wrapped around this pot (Spiraling up to the very top). And let’s imagine a usual coal powered plant and how it works.

The question is how much electricity can be produced from the steam that occurs from the process of the water boiling whilst passing around the hot pot. (After the water boils, it creates steam which spins a tubing which is connected to a generator ect.)

Your help would be highly appreciated.

Thank you in advance and best regards

 

[physwizard]

Where are you going to get the magma from? What are you going to do with it after it cools down and solidifies? How much electricity produced will depend on knowing how much 'magma' do you have available, How much of water is available to be heated, how much of steam pressure the boiler can withstand, size of boiler, etc.

 

[Iou]

Where are you going to get the magma from? What are you going to do with it after it cools down and solidifies? How much electricity produced will depend on knowing how much 'magma' do you have available, How much of water is available to be heated, how much of steam pressure the boiler can withstand, size of boiler, etc.

Dear physwizard, thank you for your reply

This is a theoretical scenario. 50 MT of Magma in a pot. It will be disposed of after it solidifies; the amount of water available is unlimited. Not sure about the pressure.
Here is a link to a picture:

http://www.hk-phy.org/energy/power/elect_is/images/powerplant_still_eng.gif
This should help understand the scenario I am talking about.

In my case however, instead of the pipe passing thorough a room which has boiling coal in it, it will be wrapped around a huge metal pot filled up to the top and containing molten magma.
A coal powered plant produces about 1800 Kw/h from 1 MT of coal. How much Kw/h could be prodused from 50 MT of 700 C magma held in a pot, creating steam out of the water which passes through a pipe wrapped around it. Pipe can be any thickness.

Would like to get a rough idea

Thank you and best regards.

 

[physwizard]

Hi, theoretically, the heat released by the magma during cooling will be given by: Heat released = mass * specific heat * (700 C - (Temperature to which the magma is cooled)). If you allow it to cool so much that it solidifies then you will have to add the latent heat to this, this would be = mass * Latent heat of fusion. This would only be the heat released during cooling. Only a fraction of this would be converted to electricity. So you would have to multiply this with the efficiency that you expect your power plant to have to get the amount of energy converted to electricity. I guess thermal power plants typically have efficiencies of roughly 40%.

 

[Jobrag]

In essence we already do this google geothermal energy.

 

[Grombely]

Iou,
The heat transfer through magma is quite poor- even more so when solid as it would be at 700 C . The heat carrying capacity for water is also very high, where as magma's would be low. Your system would need a lot of piping or slow water flow to work.