# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: george on 28/12/2006 17:14:39

Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: george on 28/12/2006 17:14:39
Since the Sahara is a very sunny place, is currently unused by anybody and probably doesn't have too many planning regulations, assuming we could exploit it, how much solar energy could it yield, and what would be the best way to collect this energy i.e. solar cells, Stirling engines, Venturi effect generators etc?

George
Title: Re: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Heliotrope on 28/12/2006 21:41:39
Assuming you could overcome the limitations of the shifting sand etc...

Sahara desert area = 9x10^6 km^2
Let's assume 50% of it is too difficult to put panels on.
Useable area = 4.5x10^6 km^2

...Actually forget the calculation. I found a reference :

Quote from: Wikipedia
In the Sahara desert, with less cloud cover and a better solar angle, one can obtain closer to 83 W/m². The unpopulated area of the Sahara desert is over 9 million km², which if covered with solar panels would provide 750 terawatts total. The Earth's current energy comsumption is around 13.5 TW at any given moment (including oil, gas, coal, nuclear, and hydroelectric power).

http://en.wikipedia.org/wiki/Photovoltaic_array#_note-0
Title: Re: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: realmswalker on 29/12/2006 06:11:56
Lets start an organization dedicated to covering the Sahara with solar panels!!!!!!!!
Title: Re: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Heliotrope on 29/12/2006 19:16:33
Good plan.
All we need to do it get permission from :

Algeria
Libya
Tunisia
Mauritania
Western Sahara
Mali
Niger
Sudan
Egypt
Morocco

You get them to agree and you're laughing.

Title: Re: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Heliotrope on 29/12/2006 19:17:28
Oh, and by the way...
Where will all the electricity be used when it's generated by all of these independent, sovereign nations ?
Are you assuming they will simply hand it over to the West ?

Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: pavlovs dog on 02/02/2007 23:07:15
Yes Heliotrope, if you wanted to make some sort of profit from the energy produced, but isn't the point of solar energy to produce "clean" energy - by clean i mean no carbon emissions and no physical resource from the earth?
Lets face it all ye tax payers. electricity is never going to be free. If the Sahara was producing all of the earths electrical needs(assuming we found an efficient way to clear all the dust off from the PV cells and found funding for it all) all of the sovereign nations, who are mostly struggling LEDC's, will have a source of money and possible jobs. It wouldn't make a difference if they owned it or not. They would sell the energy to the national grid to improve their economy and I'm sure that they want the earth to last long enough for their far future generations to live in.
nonetheless, using the whole of the Sahara for PV cells is quite drastic and would cause a number of ecological and ethical problems...

from Pavlov's dog himself! [;D]
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Soul Surfer on 03/02/2007 00:21:46
It is interesting to note that the major substance used for solar cells is silicon a major constiruent of the sand.  What is needed is to design a self powered locally operated process for manufacturing solar cells out of the local material that can also replicate itself from local materials and given a few years we have the problem toally sorted out!
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: neilep on 03/02/2007 02:42:57
How much energy, resources, would it take to manufacture and install enough Solar Panels to cover the Sahara ?
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Karen W. on 03/02/2007 03:05:26
I could not even imagine..
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: neilep on 03/02/2007 04:01:31
I am just wondering how long it would take before we get some dividend in the way of free energy after the time and energy and resources that it will cost to set the thing up in the first place .

There will have to be a vast infrastructure created to distribute the energy too...

Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Karen W. on 03/02/2007 04:04:50
That is a good question.. Haow would they keep the panels free from sand etc.. Seems like and impossible job... Would the units have to be sealed within some lkind of case so that pitting from the sand would not occur or would that have no effect on the solor panel?
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: paul.fr on 11/02/2007 23:51:16
I am just wondering how long it would take before we get some dividend in the way of free energy after the time and energy and resources that it will cost to set the thing up in the first place .

There will have to be a vast infrastructure created to distribute the energy too...

Quite a while, if ever. Sellafield was supposed to produce free or "too cheap to meter" electricity!
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: syhprum on 12/02/2007 11:56:37
I always thought that the primary purpose of Sellafield was to produce Plutonium for bombs and electricity production was a bit of a myth
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Batroost on 12/02/2007 23:25:58
Ok. A little confusion here...

Sellafield is a big place. Amongst other things it includes:

- the windscale piles which were plutonium producing (only)
- Calder Hall whose MAGNOX reactors produced both plutonium and electricity for fifty years
- The Windscale AGR - prototype advanced gas reactor (electricty producing)
- Lots of reprocessing, vitrification and waste handling plant including THORP (Thermal Oxide Reprocessing Plant) used to reprocess both AGR and light water fuel.

Incidentally, the line "too cheap to meter" was used about the 'civil' reactors at Calder Hall when they were officially opened in 1956.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: heusdens on 26/05/2007 16:21:17
Lets start an organization dedicated to covering the Sahara with solar panels!!!!!!!!

http://www.trecers.net/ (http://www.trecers.net/)
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: heusdens on 26/05/2007 16:27:37
That is a good question.. Haow would they keep the panels free from sand etc.. Seems like and impossible job... Would the units have to be sealed within some lkind of case so that pitting from the sand would not occur or would that have no effect on the solor panel?

Interesting question, but solvable in my opinion.
You would not just create electricity but also use these plants (preferably concentrated solar power plants) also to desalinate water.
The water can be used to grow plants.
You would just need to take an area and protect it with dunes,and irriate the dunes to grow plants on them , so the sand won't be blown away.

But realistically seen such plants won't be built in the middle of the Sahara, but somewhere near the coast.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: paul.fr on 29/05/2007 21:15:32
That is a good question.. Haow would they keep the panels free from sand etc.. Seems like and impossible job... Would the units have to be sealed within some lkind of case so that pitting from the sand would not occur or would that have no effect on the solor panel?

Interesting question, but solvable in my opinion.
You would not just create electricity but also use these plants (preferably concentrated solar power plants) also to desalinate water.
The water can be used to grow plants.
You would just need to take an area and protect it with dunes,and irriate the dunes to grow plants on them , so the sand won't be blown away.

But realistically seen such plants won't be built in the middle of the Sahara, but somewhere near the coast.

They can be sealed, but i forget how. Although this is not realy a problem, if you assume that to save energy and cost the units are made on site using local labour andmaterials it would be just as cheap to manufacture and replace the units when that is needed.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: another_someone on 29/05/2007 21:52:27
They can be sealed, but i forget how. Although this is not realy a problem, if you assume that to save energy and cost the units are made on site using local labour andmaterials it would be just as cheap to manufacture and replace the units when that is needed.

Sealing them will not be a problem, but the problem is, whether they are seeled or not, if they get covered in sand, then it will stop the sunlight getting to them.

Nor can they simply be made on site.  Making solar panels is like making any other silicon based electronic device, it needs ridiculously pure silicon made in ultra clean rooms.

One also has to look at the environmental impact of covering a significant proportion of the Sahara in black silicon panels.

One also has to look at all those countries that are currently providing oil, countries from Venezuela, to Nigeria, to Indonesia, to the Caucuses.  How will they react to having to buy energy from the Sahara region?  Ofcourse, many of them have almost as much sunlight as the Sahara region, but to utilise it, they would need to cut down lots of forest - but if they don't have the money to pay for Electricity from Morocco or Libya, what are they going to do?

Aside from coverring the Sahara in silicon panels, how are you going to get the electricity to the markets?  Are you going to cover the rest of the world in very very think aluminium transmission cables (for Scandinavia to get its electricity from the Sahara, it will have to traverse the whole of Europe; and for the Americas, that will mean a very very thick transatlantic cable that needs to be laid and maintained).  All o this cable will have resistance, which will cause power to be lost as heat, and as massive electromagnetic fields around the cables.  The other option is to convert the solar power into chemical energy (e.g. some sort of hydrocarbon), and then ship it as we presently ship oil.

Finally, even if the electricity is made in
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: paul.fr on 29/05/2007 22:09:22
Sealing them will not be a problem, but the problem is, whether they are seeled or not, if they get covered in sand, then it will stop the sunlight getting to them.

Nor can they simply be made on site.  Making solar panels is like making any other silicon based electronic device, it needs ridiculously pure silicon made in ultra clean rooms.

Why not? I simply state that they are made on site, that does not refer to some grotty shed in the desert. On site, in a factory based in the area, for practical reasons of repair and relacement as opposed to overseas and shipping them in.

Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: nebular on 22/09/2007 20:21:42
This is a wonderful idea, unfortunately not without many of the issues raised to overcome, political, withstandable technology produced in clean conditions, maintenance. Also delivering the electricty to continents around the globe.  Ideally it would be great to see North Africa and the Western Med using it as their energy sustainance, but for America Asia or Europe, it seems we will have to go for More windfarms and radicalisation in the prevention of the offsets we produce,.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 26/09/2007 15:47:07
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lightarrow on 26/09/2007 19:39:21
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... [;)]
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 26/09/2007 23:22:26
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Andrew K Fletcher on 27/09/2007 08:47:33
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/
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Pumblechook on 13/11/2008 20:19:36
It would be very expensive electricity before you even consider the cost of getting the power to where it is needed.

Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 13/11/2008 23:15:50
Quote
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Pumblechook on 14/11/2008 11:20:39
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%..
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 14/11/2008 11:35:27
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?
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Pumblechook on 14/11/2008 12:11:10
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 14/11/2008 13:10:08
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: dentstudent on 14/11/2008 13:14:55
No doubt this "stream" will be seen as a PM machine....sorry, I seem to have stooped to cynicism. Must be my age....
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: Pumblechook on 14/11/2008 17:15:36
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.
Title: How much solar energy could the Sahara desert produce if covered in solar cells?
Post by: lyner on 15/11/2008 22:47:36
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.