Solar Cell Achieves 40% Efficiency

Fysiks Wurks found on the U.S. Department of Energy website news of a breakthrough in solar energy efficiency. From the article: "...with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance." A page linked from Wikipedia's article on solar energy calculates the land area that would need to be covered by solar collectors at 8% efficiency to meet the world's energy needs (using 2003 figures). At 40% efficiency, it looks like a square 265 miles on a side in the American southwest would do it.

Comments

transport losses?

[toQDuj]

yes, a few hundred miles in the american southwest would do it (anyone objecting to using Texas?), but only if the entire world lived in the american southwest. As it is, energy losses due to transportation are quite significant and hinder an all-out world power source plan.

B.

Re:transport losses?

[jtorkbob]

Hydrogen conversion has its own inefficiency, so that's out.

That statistic is simply an illustration in any case. Obviously there are some other places in the world where such installations could be put; perhaps some less sunny ones would require more space to reach equivalent capacity.

In any case, I think that a 100% solar earth is unlikely:

* Much of the time it is night, and storing that much juice in batteries is impractical. Things like hydroelectric storage and thermal solar plants could help with this problem, but its a whole different research issue.
* In the event of, say, a major volcanic eruption or meteor impact, world power production would plummet. That could be the least of our worries.

Solar and wind are like the icing on the clean power cake. They are great for the role they serve, but you can't have them for dinner without getting a stomach ache.

Re:transport losses?

[jtorkbob]

I think the best use for this technology would be to put it on every roof in in America (and Europe and eventually the world), and use nuclear power as a method to buffer against periods of low sunlight.

I agree that local micro power is another good peice of the puzzle. My number one goal in life is to eventually live in a home with a net energy surplus. Of course, my penchant for running Linux on old hardware might turn into a barrier to this.

While the major volcano/meteor event you mentioned could deplete the nuclear buffer, it would do that (and worse) now.

Well, given a 'minor' event like Mt. Saint Helens, light blocking would only be a minor concern to the overall energy supply as we have it now. Obviously ash and debris in equipment, supply chain interruption and so on would be another issue entirely.

Hell, we could sell of the surplus nuclear energy to subsidize projects like the complete mechanization of food production, -- obviously using our nearly free energy. Or just lower taxes (though I would prefer the former)

Well, that's a different question, one I hadn't considered too deeply. Still, until we develop a 'perfect' single energy source a la Mr. Fusion, there will have to be a wide variety of energy sources in order to have a stable energy system. Nuclear/fossil systems require finite and largely imported fuel. Wind, solar and geothermal require specific geography. Hydroelectric fsks up the ecosystem. Each has its place in the ideal system, however limited.

Re:transport losses?

[Eivind]

Sure. That's actually another *advantage* of solar.

It's a lot more practical to scatter a large numer of smaller solar-plants around than it is to do the same with nuclear, oil or coal-powered plants.

If you do this, for example, by installing them on the roofs of homes you get 2 extra benefits:

• It makes the house less hot. If 40% of the sun is converted to electricity, then that's 40% which is *not* converted to heat. Decreases the demand for AC.
• It produces the most power precisely on the days when the demands on the grid is at its peak. (assuming warm/sunny areas) Which, is optimal if your goal is reducing the strain on the grid.

Re:transport losses?

[Eivind]

But that's just non-useful pedantry.

At a large enough distance, all things are the same. Which removes distinctions which in real life are useful.

For example, the phrase "renewable energy-source" actually has meaning. True, one can claim that *no* energy-source is renewable -- because entropy will always increase, and for example solar-power is nuclear, and infact the sun is going to run out of fuel at some point.

Or you could argue the oposite; that pretty much all energy-sources are renewable; oil coal and gas come from organic matter afterall, so given a long enough time, there's no reason why they shouldn't renew.

But this is just playing word-games. You've told nobody anything new with this. We're talking here and now and on human timescales.

Oil won't renew -- in the next 10, 100 or 1000 years. So for practical purposes it's non-renewable.

The sun won't run out of hydrogen the next 10, 100 or 1000 years, and furthermore it doesn't run out any faster if we install solar-cells. So for all practical purposes, the sun is a constant source of energy.

Re:transport losses?

[indifferent children]

Is energy really expensive enough to justify covering your house in solar cells?

Energy as we collect it now, has some non-obvious costs. What does pollution from burning fossil fuels cost us in terms of healthcare? What will sea-level rise cost us? (hint: NYC, LA, DC, Miami, New Orleans, Mobile, and others are very close to sea level, and those are just the US examples.) Would we really have spent $300B and 2,906 American lives (so far) in Iraq if we didn't need to "stabilize" the region that supplies most of our oil?

Part of every dollar that you pay in taxes, at the store, at the hospital, in fact pretty much everywhere, is an energy cost.

Re:transport losses?

[maxwell demon]

The problem with solar panels is PRICE. That is the nut that needs to be cracked. If a panel is only 10% efficient, but not much more expensive than a similar sized roofing slate, it suddenly becomes economical to re-roof the house the next time the roof needs attention. However, it's not even near that price. An 80 watt panel currently costs around GBP£250 which is fantastically expensive. There is no way I could even remotely afford solar roofing at those prices, however much I'd like it. The price per peak watt needs to be about a tenth of what it is now.
  According to the article, the new solar cells would cost about $3/watt. I don't really know the exchange rate between $ and £, but AFAIR it's about a factor of two. That would give £120 for an 80 watt panel. Still not 1/10th, but at least less than half the price.

Also note that in your calculation you also have to add the savings in electricity. That is, you don't have to have equal price to conventional roofing, but you have to have the equal proce of conventional roofing plus the saved payment of electricity in some reasonable amount of time. So if the money saved on your electricity bill in, say, the next three years makes up for the extra cost of solar cell roofing, it's still more profitable to do it. (Well, actually you'll also have to account for the interest you would have gotten for the money during that time, because the money you pay for electricity next year will still give interest this year, while the money you spent on the solar panel will not.)

Re:Cost is the issue

[Rinikusu]

Erm.. deserts are empty.. of what?

Lots of animals and wildlife flora/fauna live in the deserts. Many of which are endangered. Many of which provide valuable eco-service to the land around them. It might not be prudent to just blot out the sun with solar collectors and think everything's going to be okay.

I'd rather see these on rooftops, supplementing power sources in a more local fashion where their impact will be minimal.

God, geeks are so incredibly stupid

[Anonymous Coward]

1. Deserts are not empty. They have an ecosystem.

2. There is no reason at all to fill a desert with solar cells, and then transport the energy across to the other side of the planet. Solar cells are installed locally, like on your roof, or in your back yard, on every roof across the planet. Most of the electricity consumed would be as Direct Current right from your rooftop, with an inverter converting for those appliances you still insist on retaining that us AC.

3. For dense city sitatuions with high rises who's energy needs can not be met by rooftops, etc., electricity can be sent via conventional AC lines across the conventional power grid from say no more than 50 miles away. Not the other side of the world.

4. Those who produce an excess of electricity beyond their need, sell it into the grid.

Re:Cost is the issue

[bogjobber]

Looks like someone needs a refresher course in ecology. Deserts are very rich and diverse zones. Remember, a desert isn't just sand dunes. Just because it isn't green and not many people live there (the US West/Southwest) doesn't mean it's a barren wasteland. Also, the reason why the desert isn't farmland is because there is no water. The thing preventing Nevada from being a rich agricultural region is a rather large mountain range, not too much sun. Unless you can find a way of getting more water to the desert (like the Northwest) then it isn't going to produce squat.

Besides, other areas of the country still receive sunshine. I bet when you take into account the costs of maintaining the transmission infrastructure as well as the risks associated with a centralized power source most of the solar stations would be stationed near population centers instead of concentrated in one area.

Thermal is slow to start - but you can be prepared

[dbIII]

Actually - that's not true at all. Coal fired plants using pulverized coal can do so

It takes quite a few hours to build up steam from a cold start and it wears everything out quickly by thermal fatigue if you have a lot of restarts. What does happen is something called spinning reserve where coal is being burned and the turbines are spinning but the generators are not connected. The generators can be attached by a very large clutch and more pulverised coal can be fed in to bring things up quickly - I'm too out of touch to know how quickly now and worked in new plants of an old design. With hydro you just turn on the tap and things happen quickly - thermal needs time (which includes oil and nuclear too for people who forget that nuclear is stream power).

Anyway - the troll way above was doing the "one true energy" thing which you only get from idiots or salesfolk. Just becuase photovoltaics are not a drop in replacement for every base load power source on earth does not make them useless. In remote areas they have proven themselves for decades.

Re:PROGRESS WE BE SCREWED!

[Silverstrike]

Solar cells will come down in price too, of course, and presumably get more efficient.

Yea, if only they could manage that! We could have a spirited argument on Slashdot article about it!

vandals could easily damage your solar cells

Well, when they're making them more efficent (sometime in the future, obviously), they could also work on making them indestructible as well! Like my windows.

They'd also become less efficient over time and likely just need repair from general aging problems, and in the end you're probably losing more money than by using national power.

Yes! Obviously they'll go bad, because everything has a short lifespan....ya know, like my house's foundation. It's only got 6 months left!

Ok, ok, enough of that. Seriously though. Did you read the SUMMARY? Did it even occur that maybe you should look up the lifespan of a solar panel before MAKING UP statistics? (40+ years, according to a cursory Google Search for "solar panel lifespan"

Please stop, its just painful.

Re:Grandpa was a Buggy Whip Salesmen

[anvilmark]

Thank you for so graphically describing how a small % of people can come to own the vast majority of the world's wealth, the subject of another discussion.
Circumstance dealt him a series of "losing" hands, but he didn't bitch and moan and expect someone else to "make it right". He worked, very hard I'm betting, and became wealthy.

Based on what's I've read in that other discussion, he must have been a very wicked and greedy man.

I salute him.