solar thermal the way to go for large-scale power generation?

[Crispy]

scratches aren't going to be that massive a problem, unless there's sandstorms I guess.

 

[david dissadent]

scratches aren't going to be that massive a problem, unless there's sandstorms I guess.

Alot of people are emphising the Sahara as a place to have this.

 

[WouldBe]

Alot of people are emphising the Sahara as a place to have this.

The other problem there is the drifting of the sands which could stop the collectors tracking the sun.

 

[david dissadent]

The other problem there is the drifting of the sands which could stop the collectors tracking the sun.

Dust plus machinery = fail.

 

[kerplunk]

Clean is probably more of a problem than scratch free.

never heard of a problem keeping windows clean either.


well 'cept my place maybe...





Google say they're in for 'undreds of millyuns

http://news.bbc.co.uk/1/hi/sci/tech/7115786.stm

 

[spacemonkey]

I'm visting this as part of my MSc course next year.

 

[david dissadent]

never heard of a problem keeping windows clean either.

They lie at an angle, and any amount of dust will affect performance. Dry enviroments can be very dusty. Its a consideration but probibly not enough to kill the idea.

 

[xenon]

On the PV front, Nanosolar are opening the worl'ds largest factory producing thin film panels, 2008.

http://www.celsias.com/2007/11/23/nanosolars-breakthrough-technology-solar-now-cheaper-than-coal/

They don't use silocon or glass. Cheaper, more efficient and easier to install is what they claim. There are quite a few skeptical comments about those claims though. Not least availability of the raw materials they use instead of silicon.

 

[free spirit]

They lie at an angle, and any amount of dust will affect performance. Dry enviroments can be very dusty. Its a consideration but probibly not enough to kill the idea.

I'd imagine someone going round with a squeegee, water and a drop of vinegar once a week should sort that out (though i reckon that job'd soon get a bit repetitive)

 

[stdPikachu]

Dust plus machinery = fail.

Stirlings are hermetically sealed though, no?

Obviously, tracking systems aren't and are more prone to failure, but given the example of the Sahara (almost equatorial) with the sun being ~overhead all day, the reflectors would really only need to track azimuth, no? Efficiency would drop slightly but it'd make them significantly cheaper to build and maintain.

 

[Crispy]

Stirlings are hermetically sealed though, no?

Obviously, tracking systems aren't and are more prone to failure, but given the example of the Sahara (almost equatorial) with the sun being ~overhead all day, the reflectors would really only need to track azimuth, no? Efficiency would drop slightly but it'd make them significantly cheaper to build and maintain.

I wonder if there's a passive sun alignment system that could be effectively maintenance free? Some sort of heat-adjusted counterweight arrangement?

 

[WouldBe]

never heard of a problem keeping windows clean either.

Windows tend to be vertical so unless they are wet dust won't totally cover them. However with this

if you get a sand storm you could find the mirrors covered in tonnes of sand and it will take more than a drop of vinegar and a squeegie to remove that lot.

 

[WouldBe]

I wonder if there's a passive sun alignment system that could be effectively maintenance free? Some sort of heat-adjusted counterweight arrangement?

I was thinking of sand drifting in the night and piling up against the rotating mirrors so that they wouldn't be able to move to track the sun.

 

[Crispy]

if you get a sand storm you could find the mirrors covered in tonnes of sand and it will take more than a drop of vinegar and a squeegie to remove that lot.

Must say I hadn't thought of that. THe upside with the solar tower design, however, is the massive reduction in complexity. Wind turbines have minimal moving parts, and there's no superheated steam or chunks of metal spinning at 1,000's of RPM.

 

[kyser_soze]

Just build a wall around the mirrors high enough to deflect most sand from building up over the mirrors?

Or go all Dune about it and create a wholly self sufficient desert station with windtraps, dew collectors etc etc

 

[Crispy]

Just build a wall around the mirrors high enough to deflect most sand from building up over the mirror

I don't think so

No, any facility in a sandy/windy place is going o require maintenance of some sort.

 

[kyser_soze]

We can dig oil out of Siberia now, I'm pretty sure someone can come up with a way of maintaining structures and moving parts in the desert...

 

[Crispy]

Yep. Not an insurmountable problem.

 

[kerplunk]

Stirlings are hermetically sealed though, no?

Obviously, tracking systems aren't and are more prone to failure, but given the example of the Sahara (almost equatorial) with the sun being ~overhead all day, the reflectors would really only need to track azimuth, no? Efficiency would drop slightly but it'd make them significantly cheaper to build and maintain.

But it strikes me the degree of mechanical parts to tilt the mirrors slowly through a single plain twice a day would be a fairly minor amount of low friction movement. I wouldn't have thought wear would be that much of a problem myself. Compare say to a well derrick that's nodding it's head up and down a thousand+ times a day - more cycles than the mirrors would get in a year.

 

[Crispy]

Exactly. You could go incredibly low tech. Maybe even dispense with bearings.

 

[Fuchs66]

Solar thermal is, in the right location, a useful power source but it isn't the only one and it isn't universally applicable, just one of a bag of options.

It does appeal to me though, takes me back to burning stuff with a magnifying glass as a kid

 

[kerplunk]

Exactly. You could go incredibly low tech. Maybe even dispense with bearings.

Could be a boom time for meccano

 

[stdPikachu]

Solar thermal is, in the right location, a useful power source but it isn't the only one and it isn't universally applicable, just one of a bag of options.

The great thing about solar is that it flourishes in the same environments that humans don't. Sahara is a bit of an edge case, but certainly places like Nevada (huge swathes of uninhabited desert) it's got massive potential, particularly given its proximity to California/Los Angeles and Las Vegas.

Pretty much all eco/renewable energy sources are highly location dependent - solar needs sun, tidal needs sea, wind needs... er... wind. The great thing about electricity is it can traverse vast distances with minimal energy losses.

As an aside, did anyone catch that episode of Grand Designs with the heating system that basically consisted on a load of pipes beneath the soil in the garden? Theory is that the ground will warm up during the day, warming the tubes and transferring it to the underfloor heating. Not sure how well it would work in practice but it did have the advantage of being cheap and simple and not involving the questionable eco-friendliness of photovoltaics.

 

[Crispy]

Google is investing '100s of millions' into green energy, including solar thermal (http://www.esolar.com/)

http://www.google.com/intl/en/press/pressrel/20071127_green.html

Ooh, useful graphic. Market for solar thermal power.

 

[two sheds]

I was thinking of sand drifting in the night and piling up against the rotating mirrors so that they wouldn't be able to move to track the sun.

The Ausra mirrors are turned upside down at night and during storms.

 

[xenon]

I thought piping electricity long distances was quite problematic. Needing very high voltages and transformers on route to compensate for drop off.

Are they're pheisable, economic methods available now for transfering electrical power across oceans?

 

[Crispy]

No, not really (feaseable). Solar's only good for primary power in sunny countries.

 

[Fuchs66]

No, not really (feaseable). Solar's only good for primary power in sunny countries.

but often it's the case that these are the countries that need a leg up as far as power is concerned without being tempted to go down the fossil fuel/nuclear route (if at all feasible)

 

[stdPikachu]

I thought piping electricity long distances was quite problematic. Needing very high voltages and transformers on route to compensate for drop off.

You do, but that's part and parcel for any part of a national (or even international) grid. Going to have a look-see to see what sort of power loss you can expect with a power line 2000 miles long (as a worst-case scenario). Step up and step down transformers, although a high initial expense, are ridiculously efficient (getting more efficient as size increases if I'm remembering my physics properly).

Quick consultation of wikipedia shows that the UK national grid loses about 2.5% of its peak output over the high voltage network, with the losses involved in "last mile" connections bringing the grand total up to about 8%.

Same article also references power losses involved in traversing latitudes, noting that S>N power is more efficient that N>S power - presumably this is due to increased resistance when flowing "against" the Earth's electromagnetic field?

An interesting snippet in another article points to HVDC (high voltage direct current) which has the benefit of not having to deal with AC phase changes over long distances, and then convert them to the local phase at the substation level. The only significant downside seems to be the high cost of the inverters needed at each end.

/me tries to find an eectrical engineer to bribe

 

[xenon]

Maybe feaseable.


Some proposals mentioned here for plans to distribute electricity over long distances.
http://www.trec-uk.org.uk/elec_eng/grid.htm

"Trans-Mediterranean Renewable Energy Cooperation (TREC)
propose an HVDC grid spanning the whole of Europe, the Middle East and North Africa (EUMENA) to take advantage of the enormous quantities of energy falling
as sunlight on hot deserts, and wind energy in those regions too (see also
TREC-UK)."