Solar Panels

bernardgreen said:
And people who insist that PV wind turbines are the only acceptable means to generate should be the first people to be switched off at night when there is no wind.
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Tesla powerwalls are an interesting development for storing the generated energy. Expensive at present even though Tesla have indicated that they won't overly capitalize on the technology. Rightly or wrongly, Tories cutting the FIT subsidy have murdered this as a domestic innovation for the forseeable future. Commercial might still be a runner though.

https://www.tesla.com/en_GB/powerwall

Back to the OP,

Here's another way to make money out of solar energy. 6% dividend pa on 'Foresight Solar Fund' shares. Tempting?

http://www.solarpowerportal.co.uk/n...o_raise_30_million_to_power_acquisition_drive
 
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Does anybody have reliable information on the payback period, in terms of carbon, for wind turbines? I've seen plausible estimates of one year, 22 years, and pretty much everything in between. Challenging the manufacturers of turbines, they say they can't offer a precise figure because they don't know (and perhaps are unwilling to find out) how much energy and material is needed to install and connect their products, whereas the only wind farm operating company who replied to me couldn't provide a figure because - can you see what's coming - they don't know how much energy/material is used in manufacturing the turbines.
A fairly rigorous study by an engineer I'm acquainted with suggests that a medium-sized wind turbine installed fairly near the grid has to operate for 7 years before it has saved carbon emeissions equivalent to the energy used in its construction, installation and connection. The significance of that is that if the number of turbines built/installed/connected doubles during that period, there has actually been an increase in carbon emissions!
 
stillp said:
A fairly rigorous study by an engineer I'm acquainted with suggests that a medium-sized wind turbine installed fairly near the grid has to operate for 7 years before it has saved carbon emeissions equivalent to the energy used in its construction, installation and connection. The significance of that is that if the number of turbines built/installed/connected doubles during that period, there has actually been an increase in carbon emissions!
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Given that there will inevitably be an up-front carbon cost, it is equally inevitable that there will be an initial increase in overall carbon emissions during a period during which the number of newly manufactured and installed of turbines is an appreciable proportion of the total in service. The benefits come later, when the majority (at least, a substantial proportion) of the in-service tubines have got beyond their (carbon) break-even age.

That phenomenon is obviously not peculiar to wind turbines. Exactly the same would be true of, say, a large-scale campaign to improve the energy efficiency of all buildings in the country (insulation, double/triple glazing etc. etc.). Again, there would be an appreciable carbon cost during the early days/years, util the benefits started taking over.

The real concern with things like wind turbines (of finite life expectancy) probably relates to the relationship between the (carbon) 'break even period' and the expected in-service life expectancy of the turbines. If the life expectancy were not much greater than than break-even period, then the anticipated medium-/long-term benefits might never come (at all or appreciably), since the manufacturing and installation (carbon) costs would recur almost as fast as the previous manufacturing/installations (carbon) costs had 'broken even'.

Kind Regards, John
 
Yes, another issue is the drop-off in performance as they age. Again estimates vary but one pro-wind group in Scotland has estimated that the efficiency will halve after 7 - 10 years.
 
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The other one you get from windmill supporters is the "when we've done, there'll be nothing at all left but a green field" argument - usually following up with how long nuclear takes to clean up. Having seen the size of the foundations for a windmill tower, I very very strongly suspect that the claim is complete and utter bull - and there's a massive lump of reinforced concrete left behind.
I've not had the opportunity to try it yet, but it might be interesting to ask windmill people if their towers include radioactive waste :whistle: Reason for asking is that from some of the engineering talks I've been to - there's a lot of steel comes out of decommissioning nuclear plants, a lot of it has never been near the reactor but it's still classed as "nuclear waste". At least some of that has been recycled into windmill towers. I suspect that might get some of them frothing a bit :evil:
 
SimonH2 said:
At least some of that
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Do you mean it goes into the metal recycling heap?

Aren't you concerned about the "nuclear waste" recycled into your fridge, car and food cans?

How many nuclear engineers does it take to change a lightbulb?
 
stillp said:
Yes, another issue is the drop-off in performance as they age. Again estimates vary but one pro-wind group in Scotland has estimated that the efficiency will halve after 7 - 10 years.
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If that's true, it obviously makes the sums somewhat worse.

However, I confess that I'm very surprised. What aspect of the turbines deteriorates that much in such a relatively short time, and can it not be avoided/minimised by maintenance? Does the same happen to the turbines in gas-, coal- and nuclear-fuelled electricity generation?

Kind Regards, John
 
JohnD said:
Would be interesting to see the source data
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Indeed so. As I implied, so long as one keeps it appropriately lubricated and keep the blades clean etc., I don't see why the efficiency of a wind turbine should deteriorate (markedly) with time any more than its counterparts in gas/coal/nuclear power stations.

Kind Regards, John
 
I believe that gearbox wear and loss of field strength from the magnets account for most of the reduction in efficiency. Note that it is efficiency, not output power, so a need for increased maintenance would reduce the efficiency.
JohnW2 said:
I don't see why the efficiency of a wind turbine should deteriorate (markedly) with time any more than its counterparts in gas/coal/nuclear power stations.
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The generators in conventional generation have constant power inputs and are therefore much less complex.
 
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