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corrado33 wrote:

greenspree wrote:What exactly makes solar not practical on a large scale?

You'd need miles and miles and miles of acres to produce the amount of power to make it practical. Land isn't getting any cheaper. At least that's my guess. Solar panels just aren't as efficient as we want them to be.

While PV isn't practical on a large scale yet, I think solar can be. I think the key is deserts. There are just ridiculous amounts of desert land on Earth that both have very little value and excellent solar coverage. You basically need miles and miles of mirrors with simple aiming machines attached to each. These direct the rays to a central collector (basically a big water tank). The water turns to steam and drives turbines -- which are pretty efficient since we use a similar setup in a lot of other power generating systems. A large system would have many collectors and mirror arrays.

It really wouldn't cost that much (in comparison to the billions we spend on wars and such) to build out a really large-scale system like this in the US. Once it's generating power, maintenance would be cheaper than almost any other type of power generation facility because it's a very simple system. The biggest maintenance cost is guys driving around replacing servos and cleaning mirrors.

The big issue is moving the energy from the power generating deserts to where the people are. We need some new long-distance low-loss power lines to make this work (using superconductors). Alternately we need to turn the generated electricity into something like hydrogen in order to ship it around.

Here's a picture of the one recently built in Spain:

I think the key is diversification and regionally specific energy solutions combined with efficiency and smart grid metering and storage.

Electric cars with on board batteries storing electrical energy at time when there is excess power (sunny days/windy days/etc...) and the grid drawing a bit of power off the batteries when there is low generation (at night/no wind/...)

Areas like the Bay of Fundy using tidal power, Nevada using solar, coastal areas offshore wind, mountainous areas hydro, some natural gas, some biogas in agricultural areas, combined heat/power plants to make the most of our fuels, limited nuclear (we still need isotopes for medical and scientific research anyways)

Energy efficiency so our heating and cooling costs are minimized, energy codes making sure we don't build inefficiently in the first place (no more uninsulated basements!!!) Better options for light rail and transit so we don't all need cars. Mandated lifespans for consumer goods (no more disposable society!!!!).

I am writing a book right now about the process of building our straw able home and a lot of my writing is going off on tangents about societal problems as a whole. Maybe I need to start another book....

MK500 wrote:

Is it me or do the Spaniards not know what they are doing. Those mirrors are pointing every which way and are definitely not focused on one spot.

The mirrors are a great idea and get rid of the problem with maintaining solar panels. The latest thing I have heard of them doing is storing the energy in liquid sand, rather than heated water. Supposedly it will retain the heat from the day for up to 12 hours. It is things such as this that are making solar more viable.

sjvsworldtour wrote:The mirrors are a great idea and get rid of the problem with maintaining solar panels. The latest thing I have heard of them doing is storing the energy in liquid sand, rather than heated water. Supposedly it will retain the heat from the day for up to 12 hours. It is things such as this that are making solar more viable.

Water already has a very high specific heat (for normal/safe substances). It's GREAT for storing heat. It takes a while to heat up and it stays warm for a very long time. It's value is about 74j/mol*K. The only one I can find for sodium silicate are 81 and 100, so I guess it's a bit better. Still, water is easier to deal with and safer. Water has one of the highest specific heat values for common substances.

corrado33 wrote:

MK500 wrote:

Is it me or do the Spaniards not know what they are doing. Those mirrors are pointing every which way and are definitely not focused on one spot.

LOL Wow, I picked a bad picture. It looks like half those mirrors were facing the wrong way. Maybe they were doing diagnostics or something when they shot that? I totally didn't notice until you said that. Maybe that array doubles as a "death ray" and they were taking out an enemy aircraft or something

MK500 wrote:LOL Wow, I picked a bad picture. It looks like half those mirrors were facing the wrong way. Maybe they were doing diagnostics or something when they shot that? I totally didn't notice until you said that. Maybe that array doubles as a "death ray" and they were taking out an enemy aircraft or something

Hahaha death ray. Play fallout 3 much? (Exact same scenario, same type of plant that was secretly a death ray by the miilitary)

I have seen a show on the Spanish solar plant. Sometimes the 'lens system' (not an actual lens but..) overheats and mirrors with maximum heat have to face away from the tower. It also allows to cool the frame so the mirror doesn't warp. This is indeed one of the best uses of solar energy.

Maybe they didn't want to fry the aircraft taking the picture!

But looking at the shadows, either early or late in the day and not a lot of use for those mirrors. Maybe they go flat when the wind gets too strong?

Water converts to gas quicker than sodium would, so I believe that is why sodium is what they are pursuing, not to mention it being cheap and having better heat storage properties.