(Solar) Power to the Masses

D3 writes "This report on a solar power tower (pdf) looks extremely interesting. Maybe one day we can have international power lines where all the countries with lots of sunshine provide power to the rest of the world? How cool would that be?" The NY Times has a good article on solar power in Japan.

Comments

Google link / Mirror

[mjmalone]

Google link

PDF Mirror

Discover magazine had a good article

[bubblegoose]

Discover Magazine just did a story on something like this. Unfortunately the full story is only available in dead tree format. If you wait until next month the older article will be available. You can probably check it out at your Dentist's office like I did if you feel like getting a filling.

EnergyInovations is working on a small version. From the Discover article it discusses how they refined the stirling engine with the best tradeoffs of manufacturing costs to effiency. IIRC they are also making this small enough to make it fit on a roof top.

Geek fact of the day: A stirling engine is an external combustion engine that runs off the pressure created when one side of its engine gets very hot while the other side stays cool. The greater the temperature difference, the greater the pressure, the greater the energy generated.

Re:Discover magazine had a good article

[Lumpy]

Home power

is a better solution...

I have my cabin on the lake heated and powered without buying heatoil or electricity... and it's in northern michigan.

you can do it. and you can do it now. you just need to have a desire that outweighs the convience of simply paying a bill.

Re:Discover magazine had a good article

[gaijin99]

My ignorance is showing. Why does it take vastly less time for a wafer rejected for chip manufacture to recoup the energy spent on its production, compared to the 'typical' solar panel? 3 months versus three years? Wouldn't the rejected panel take just as much energy to produce, and probably be less efficient?

The reason is because the most expensive (in terms of energy) part of manufacturing anything based on a silicon wafer is growing the initial crystal.

The crystal must be perfect, a single bubble, crack, or deformity, makes the whole bloody thing worthless (as an aside: this is why some chip makers drool at the prospect of an orbital chip fabber, growing crystals is much easier in microgravity).

After you have your perfect crystal you turn it into wafers and "print" the microchip circutry on the wafer. The problem is that there is a fairly high chance of the printing process going wrong, which results in a rejected wafer. This is where the cheap solar panels come in. They buy the rejected wafers, scrub the failed chip off, and print the solar panel on the scrubbed wafer. Solar panels are more durable and less picky than chips, being printed on a scrubbed wafer doesn't bother them at all.

The resultant solar cell is just as good as one made on a fresh wafer. Since they didn't grow the wafer (and it would have been scrapped anyway) they count only the energy cost of scrubbing and printing the panel on the recycled wafer. I suppose if you want to get picky you could claim it costs the same as a normal panel, since energy was spent growing the crystal in the first palce, but I think its fair to discount that since the energy would have been wasted (bad wafer).

Transmission is weak link

[w42w42]

I don't know the percentages, but if you were to transfer power from say Mexico to Canada under this scenario, your energy losses would be huge.

Re:At last....

[Frymaster]

no! you mean ozone depletion:

global warming: increase in heat-retaining gasses reduce dissipation of energy from the plaent/atmosphere. since the input of energy from the sun remains constant, mean temperatures rise.

ozone depletion: stratospheric ozone (o3) blocks high-frequency solar radiation on its way to the earth's surface. less o3 means more high-frequency radiation.

since solar panels (photovoltaics) are more effective with high-frequency radiation, ozone depletion increases their output.

global warming just sucks

Re:South Pole

[stratjakt]

Answer:

Sure but it would suck.

The reason its so cold there is because what sunlight hits does so at an extreme angle.

Its hot at the equator because the sun is beaming straight down.

A square foot of ground in Mexico gets an order of magnitude more light energy hitting it than a square foot in antarctica.

Besides, it's pitch black 6 months of the year at either pole.

Australian solar tower sounds better

[macshune]

After reading the article, this plan to use sun-tracking mirrors to melt salt sounds a little more complicated than this Australian plan. Not only that, but the Australian plan scores more points in the coolness department as the project intends to build the world's tallest structure -- a tower 1 kilometer high. BTW, IANAA (I am not an australian)

Better: Local generation using combined solar/wind

[vkg]

Small is Profitable by Amory Lovins of the Rocky Mountain Institute is about the benefits of generating your electricity using small, modular power systems where you need them. It turns out that grid infrastructure is often well over 50% of the cost of providing power, and that if you simply install systems like microturbines or small-scale combined wind/solar installations (explained below), you can significantly outperform the grid in terms of end-user price and capital requirement.

That's not a big deal here, where we already have a grid, but it's a huge, huge deal in the third world.

The combined solar/wind thing works like this. Electricity demands have a thing called a "load shape" - basically demand graphed against time. It turns out that solar energy supplies match the load shape of things like air conditioners pretty well, but when the clouds come out, your solar supply goes to hell.

However, wind systems work best when there's a sudden change in temperature, causing new low or high pressure areas, so usually cloudy days have ample wind. If you combine local solar and wind systems in a single "local area grid" you get a hybrid system which produces power in almost exactly the same loadshape as your actual demand, reducing expensive overcapacity, and with excellent availability in all weather conditions.

Renewable energy requires a lot more smarts than "this is a huge factory which produces megawatts a day" - you don't see nearly the full benefit unless you actually take advantages of the full range of renewable solutions, using factors like their modularity, size, loadshape matching, low capital requirements, grid independence and many other subtle factors.

Small is Profitable is a hard read: about 400 pages of really densely argued financial and technical analysis, but it's pretty much the definitive work in the area. If you want to know more, it's the book to get.

A good site for home setups

[Mostly Monkey]

www.homepower.com is a great site That always offer their current magazine as a free PDF download. Most issues will show several complete setups including diagrams, results, and pictures of several different types of setups. Just in the past I've seen solar, hydroelectric, thermal water heating, and recipies for making bio-diesal from waste cooking oil.

Re:At last....

[Anonymous Coward]

> solar panels (photovoltaics) are more effective with high-frequency radiation

No, as a matter of fact, they are not. When the frequency is higher, the excess energy is wasted
as heat. Not only is it not used, but it heats the panels and makes them even less effective.
Work has been going on for some time on panels that can use the full spectrum, or at least a wider
swath of it.

A couple of corrections

[Once&FutureRocketman]

Just a couple of notes, from someone who is currently selling solar for a living in California:

- a "typical" residential system (2.4kW AC peak output) is going to run $9000-12000 after the state rebate
- there's also a 15% state tax credit
- the utility buyback of power is called "net metering" and they actually pay the retail price for the power (i.e. they credit you for power you produce at the same rate they charge you for what you use)

As to one of the original, unaswered questions: if you don't have batteries (and you don't need them if you are grid connected), the only maintenance required is hosing off the panels a couple of times a year. The panels are warranteed for 25 years, and generally good for much longer.