Brain spasm...

Up a ladder this afternoon, hanging insulation on the new barn when a couple of random brain cells fired up....

If PV arrays capture energy from the Sun which would otherwise be re-radiated back to the sky, from a global warming POV have we actually improved matters? Any electrical energy produced will still mostly end up as heat in the atmosphere.

The other thought relates to the American propellor trolley discussed back in February. ISTR the proponents insisting that testing the device on a conveyor is the same as testing on a surface with real wind. Umm. Surely the system frictional losses will be supplied by the conveyor motor and hence ignored in the calculations?

regards

Reply to
Tim Lamb
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Yes, because the alternative is burning (say) coal, which releases CO2 which acts like 'loft insulation' in the atmosphere. That reduces the radiation of heat back into space, and re-radiates some back to earth.

And you aren't using PV arrays to replace a mirror. So some proportion of the solar input captured would be absorbed anyway. The PV arrays just use a small amount of it to do useful work before it's converted to heat.

Once burnt, the CO2 from coal/gas/etc stays in the atmosphere a lot longer and so has a more potent effect than the tiny change in albedo from fitting a PV panel (consider if every house on the planet fitted a PV panel: what proportion of surface area would that affect?). Though I haven't done the numbers on this.

Theo

Reply to
Theo Markettos

IANA(physicist) but think the equation is quite complicated. Some or all of the infrared incoming heat could be reflected away at the same wavelength as you say, particularly for shiny metal (or white paint ?), The rest is absorbed and (i) some heats the panel which then radiates secondary infrared at a different wavelength, (ii) some gets carried away as in a water-based system or (iii) is converted to electricity in PV cells.

Check out its temperature with an IR thermometer when it has got hot in the sun. One way to reduce global warming is to paint all house roofs white.

rusty

Reply to
therustyone

Sadly PV is no alternative to anything, without storage we haven't got and probably never will have.

Its a hugely expensive fuel saving device that might on a good year knock 5-10% off your fuel bill and thats as far as any intermittent renewable can go.

Intermittent Renewable energy is half of a solution with the other half missing.

It is in fact almost completely useless.

Reply to
The Natural Philosopher

Hmm.. Half the agricultural barn roofs in the country were about to be plastered with arrays until the new Gov. saw sense:-)

BG have kindly supplied me with a prediction of gas use for the next year. There has been a dramatic reduction in energy used. I must tease out the figures so we can discuss how much is due to additional loft insulation and how much due to the new log burner.

regards

Reply to
Tim Lamb

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember harry saying something like:

You bad man. Keep it up.

Reply to
Grimly Curmudgeon

You turn them into coffee tables and sell them to american tourists

Reply to
geoff

Wait 100 years and they will be 'period features' on your all nuclear heat pumped home.

"Oh! Can we have one with plastic tiles and windows and solar panels, it's so CUTE".

Reply to
The Natural Philosopher

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