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EM. Have you actually read my 6.21am post, or are you just ignorant of thermodynamics as Brent supposes?

Jul 23, 2017 at 8:39 PM | Unregistered CommenterSupertroll

I thought there would be hotspots.

Redruth sits on the 0.12W/m^2 hotspot second from the right in Cornwall.

That would supply 1.3MW from 10,833, sq metres and a harvesting circle 3.7km in diameter.

Jul 23, 2017 at 8:20 PM | Unregistered CommenterEntropic man


The megawatt(MW) is the unit of power output of a power station.

The megawatt hour(MWh) is the unit of energy produced.

Thus a 1.3MW power station in continuous operation will produce 1.3MWh in each hour. In one day it will produce 31.2MWh and in one year will produce 11388MWh.

Jul 23, 2017 at 8:00 PM | Unregistered CommenterEntropic man


Yes, I cocked up that calculation. I was rushing to get the post finished before I left for work and had no time to check the numbers.

This is the full calculation, hopefully correct.

The proposed Redruth geophysical power station is rated at 1.3MW by various sources.

You quote the rate of heat flow in Cornwall granite as 0.06W/m^2.

To calculate the area of granite required to maintain the output from Redruth divide the rated power by the heat flow.

That is 1.3 million/0.06 = 21,666,666 square metres.

To calculate the radius of a circle of that area use √(area/π).

That is √(21,666,666/π) = 2626 metres.

That is a radius of 2.6km or a diameter of 5.2km.


Jul 23, 2017 at 7:14 PM | Unregistered CommenterEntropic man

@Entropic man, Jul 22, 2017 at 10:36 PM

At the average heat flow of 0.06W/m^2 Redruth would be harvesting the heat from a circle 16km in diameter.

201 square km is an improbably large area to frack for a peak 1.3MW output. Is it 1.3MW per hr, day, week, year?

Bonkers uneconomic scheme to appease your CO2 monster. EM, where did the CO2 in fossil fuels come from?

Jul 23, 2017 at 6:54 PM | Registered CommenterPcar

How entertaining to see lefty greenshirt Entropic Man display his utter ignorance of thermodynamics. His use of the word "just" is a classic. Know-nothing penpushers like him can solve any world problem by simplifying ad absurdum and putting the word "just" in front of the remedy. A channel tunnel? World hunger? The climate? War? We just need to....

The word "we" also needs explaining. To a lefty "we" means "other people's tax dollars".

Jul 23, 2017 at 2:02 PM | Unregistered CommenterBrent Hargreaves

If you know the size of the likely harvesting circle for Redruth we can calculate the heat flow.

Jul 23, 2017 at 9:36 AM | Entropic man

You just need a load of Cornish tin miners to dig a pair of interconnected spiral tunnels, reminiscent of the double alpha helix sructure of DNA.

Jul 23, 2017 at 10:49 AM | Unregistered Commentergolf charlie

Entropic Man. As I thought, totally unrealistic. Are all of your calculations so devoid of sense?

Jul 23, 2017 at 10:49 AM | Unregistered CommenterSupertroll


No need to look it up.

Just divide the rating of the power station by the heat flow in the rock.

1.3 million/0.06 = 21.7 million square metres. That is the area of a 16km diameter circle.

If you know the size of the likely harvesting circle for Redruth we can calculate the heat flow.

Jul 23, 2017 at 9:36 AM | Unregistered CommenterEntropic man

They've been trying the hot rocks thing in Cornwall for forty years. It started because they had the drilling expertise there as the tin mines weren't all closed. Now that the expertise is gone, why do you think the technology will suddenly transform?

The problem is that the energy extracted is not very dense so the flow must be high to get worthwhile returns. The flow declines as the rocks move after fracking. So the energy returns drop.
Forty years worth of testing has shown this to be the case. Geothermal needs to be used where the heat is already near the surface.
Try it in Bath and it might work. Though it would probably destroy the hot baths and that would be worse economically. They are a good tourist attraction.

Look, Cornwall has lots of cooling water and radioactive granite. Just put a nuclear power station there. If there is a small leak there wouldn't be anyway to detect it compared to the background radiation.
Put it in an old china clay pit and it won't even be visible. Sellafield has tourism tours so there are other potential benefits too.

Jul 23, 2017 at 9:13 AM | Registered CommenterM Courtney

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