Thursday, March 29, 2007

Save the Planet

Just an idea of what lies ahead if you think we can use huge fields of photovoltaic cells to cut consumption of fossil fuels. From a Reuters story:

SERPA, Portugal (Reuters) - One of the world's largest solar energy plants, covering the hills of a valley dotted with olive groves in southern Portugal, started delivering electricity to about 8,000 homes on Wednesday.

The solar panels, which are raised around 2 meters off the ground, cover an area of 60 hectares (150 acres) and produce 11 megawatts of electricity in one of Europe's sunniest spots -- Portugal's poor agricultural Alentejo region.
Those numbers look a little optimistic but even so: According to the DOE their electric generating capacity in 2002 was 10.4 gigawatts. So you'd need ten of these 11 megawatt solar plants to get up to a whopping 1% energy from solar. And that's in "one of Europe's sunniest spots".

Never mind that these numbers have been gussied up. Dividing those 11 megawatts between the 8000 homes, each household gets 1,300 watts. That will power one, fairly small, room air conditioner. Heck, the female types use that much to blow-dry their hair. Sure, I know that in Algortopia the women will all dry their hair by cracking the whip and making the buggy go faster, but still, we want our coffee makers to perk, right?

I'm not against renewables. Hydro power generates 20% of Portugal's electrical energy. (and in 2001, a wet year, it generated 30%) So look at the numbers: this is a state of the art project in one of the sunniest places anywhere, and it still is a half a drop in the bucket. Hydro and new-ku-lar have hugely more potential and they don't require armies of Portuguese with squeegees (an image featured in most of my nightmares) to keep the bird crap off a sea of panels.


Wally Ballou said...

Actaully 1300 Watts isn't out of line. That's average, not peak, use. It assumes you have a good battery system to store excess energyu and relaese it during peak demand.

Compare to the Gore house. 221000 kWh/year /6766 hours/year = avg use of 33,000 watts.

The average US house uses about 11000 kWH/Year, or an average constant use of only 1600 watts. Not too bad.

If the Spanish numbers are correct, that 150 Acres could supply about 6500 US homes. Assuming it's 50% as sunny in the US, call it 3250. That means each home needs about 2000 square feet of photocells. Again, not too terrible (except for current prices). It would be doable for people who want to be off the grid, especially if they live in desert locations. Someone who wants off the grid badly enough can probably reduce his consumption, too.

It could never be a primary source for urban users, but it can be a useful supplement for many, and take some right off the grid. It just shows that photovoltaic cells have gotten a hell of a lot more efficient. Let's hope they get a lot cheaper next.

Of course, the greens hate hydroelectric. There is currently a world-wide movement to destroy all dams. They will probably turn against solar, too (many now oppose wind generation). As soon as something becomes practical, they don't like it any more.

And just think of all the native flora and fauna shaded out of existence by these solar cells. A micro-catastrophe.


Wally Ballou said...

D'oh! better factor all those numbers by hours of light/day unless the sun shines 24/7. OK, so maybe it's not as practical. Still a useful supplement. And like all electronic tech, it will get more efficient and cheaper - eventually.

lumberjack said...

I was wondering about the day time - night time, problem. They don't say if it's 1300 watts average over a day, or average over the hours the sun is up. I'm guessing the latter.

Still, centralized power plants from solar is a pipe dream at this point. To even match the output of hydro, they'd have to tile country. There'd be no room for the cork trees, or bushes, or whatever it is that cork grows on.

markm said...

Much more sensibly, you tile the roofs of existing buildings with these. It's not going to work in Michigan or the British Isles, but if all the roofs in Arizona were covered, they'd have enough power left over for several other states - during the daytime that is. Batteries are a terrible way to store power for nighttime use (whether you're worried about cost and environmental impact), and the only other storage method that's really ready to deploy widely is hydroelectric pumped storage - which is another environmental disaster.

Build nuke plants. Make biodiesel out of the enviroweenies that turn out to protest.

OK, I didn't really mean that last part, but it is getting tempting...

MikeZ said...

I was in the bookstore reading a book the other day, a sort of "Whole Earth Catalog" for solar power.

One section calculates how much solar cell area we'd need to run the whole country. I didn't check their math, but they gave links to USDOE websites, so they're probably right.

They figure that a simple 100-mile square plot - say, in Nevada, where there's a lot of government land - would do the trick.

They didn't go into detail what New York was going to do when it was nighttime in Nevada.

The concept is interesting, but they go about it all wrong. The last thing we need is a centralized power source - PV or nuclear. The thing to do is smaller, distributed plants.