[lyner]

If you just PAINTED the Sahara (etc) silver / white, you would significantly  reduce the  amount of received solar energy and reduce the problem of global warming. That's about as low tech as you can get and it might counteract the effect of the depletion of the nice white, reflecting polar ice caps.

[lightarrow]

If you just PAINTED the Sahara (etc) silver / white, you would significantly  reduce the  amount of received solar energy and reduce the problem of global warming. That's about as low tech as you can get and it might counteract the effect of the depletion of the nice white, reflecting polar ice caps.

But in this way you would kill us all because of the amount of solvent dispersed in air... []

[lyner]

If you used spray paint, perhaps. Good old whitewash uses water as a solvent.
(There's always ONE isn't there?)
Actually, my suggestion is more or less serious. Global warming can be tackled in many ways - not mutually exclusive.
This would be very low tech and anyone can help. White roofs on all our houses would reflect a good few hundred watts and would help reduce radiated heat loss in winter.
Now where's my ladder?

[Andrew K Fletcher]

Let's start a group aimed at covering the Sahara desert in tropical rainforest.
Using waste water from Europe in Returning Oil Tankers that curently transport seawater as balast half way round the world for nothing.

http://andrewkfletchers.blogspot.com/

[Pumblechook]

It would be very expensive electricity before you even consider the cost of getting the power to where it is needed.

[lyner]

consider the cost of getting the power to where it is needed.

Are you implying that you may as well generate it in the same way but more locally? That would make sense. There is just not a problem of availability of Solar Radiation in many other parts of the world; you don't need blazing sunshine.

[Pumblechook]

I think figures from real installations show a capacity factor (average to peak power) of 10% in Britain. The best in the World is 15% I think so only 50% better. The costs of getting power from the Sahara to Europe would be enormous and losses would be high so that 15% will be down quite a bit.  It would be more expensive than local generation maybe. Land would be cheap in the Sahara..that would be its main advantage. 

It is no good just quoting peak power.  You need an energy yield figure for a whole year. 

You would never get sufficient land to have a decent sized array in Britain.  You would have to have lots of small ones. 

A one sq metre panel will produce maybe 15 Watts average (if that) over a full year (150W peak).

That is 130  kWh over a year.  Our usage is 4500 kWh per year.   You would need 4500/130 panels = 35
 panels.  35 Sq metres just for one house.   

Taking inverter loss.. Battery charger loss.. Loss in the charging process you would have to increase it to 50 panels at least.  50 Sq metres per household.  I think people have worked that you would need an area the size of London to supply the UK 100%.. 

[lyner]

The UK is one of the worst examples to quote in an objection based on use of area. Our population is so dense. Look at France - the situation is very different and 50Sq m per household isn't so daft.

If you were to produce a lot of energy locally from solar power, it would be worthwhile having dual voltage systems. High voltages are  used partly because of distribution losses so all inherently low voltage equipment (with transformers etc) could be fed with low voltage.
Heating needn't use solar electricity. Only the occasional High Power Motor would, in fact, need 'mains' voltage.

Reading through the past posts, I despair what fanciful, non-technical Politicians would make of the arguments and what conclusion they WILL come from. It's just too hard for the poor sods.
Whereas we can all grasp the problem perfectly well?

[Pumblechook]

I think firms offer solar PV systems for £10,000+ and you can save 'up to' 1/3 of your leccy bill..  That would be £200 in our case...  So payback time is 50 years..  As batteries need replacing from time to time and the panels would be in poor state in 50 years.. Payback time is never really.

There are so loony websites.  A bloke has two PV panels on the roof of his van..reckons it saves a hell of a lot in fuel.  I worked out it would take weeks if not months to charge a high capacity battery. 

[lyner]

The economics are a bit biased at the moment. We're in the equivalent of the 'Hard back book' phase at the moment.
If things (except energy) get cheaper like computers have done, then we can expect a very different payback calculation before too long.

BTW, I heard a R4 programme the other day in which a woman who lived on a hillside in Wales had a very modest little stream running through her land. This supplied ALL her yearly power needs for a normal household with a small Hydro Generator. She had a very good deal with the Electricity supplier, I understood.
Diversity has to be the best approach, I feel.

[dentstudent]

No doubt this "stream" will be seen as a PM machine....sorry, I seem to have stooped to cynicism. Must be my age....

[Pumblechook]

Press, TV, radio tend to take many things at face value with anything scientific or technical  and don't look at any figures or owt.   

[lyner]

0.45kW would only require a flow of 15l per second to fall by 3m.
That would almost provide Pumblechook's  4MWHrs over the year.
We're talking about less than one horsepower, actually.

Quite a 'modest stream' would be needed - definitely not a river. It could only happen in Wales / Scotland  etc. but it's not ridiculous.