40% Efficiency Solar Cells Developed

gtada writes "A story published at Physorg.com discusses recently published research into the fabrication of solar cells that surpass the 40% efficiency milestone. Such devices would be the high water-mark to date, and hint at the possibility of even more effective technology. 'In the design, multijunction cells divide the broad solar spectrum into three smaller sections by using three subcell band gaps. Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.'"

Comments

Is efficiency the problem?

[timeOday]

There is really no shortage of sunlight anyways. If only solar cells could be made cheaply. I suppose this will be great for satellites though.

Re:Is efficiency the problem?

[provigilman]

There's no shortage sunlight, true...but there's a shortage on space. Our energy needs to continue to grow more and more every year, theoretically it could get to the point where we have to cover large amounts of the planet's surface with solar collectors. The more efficient each individual collector is, the fewer we need and the less space they'll take up.

Re:Is efficiency the problem?

[SnowZero]

While space will eventually be a problem, I think cost is still the limiting factor right now. How many houses can afford to cover their entire south-facing roof with panels right now? If you see panels on a house, its usually only covering a fraction of the available area, which implies the limit is cost.

Right now, we've got ~40% efficiency panels which are very expensive, and 1-2% panels which are cheap to make. I think the real breakthrough will be when we can make 20% efficiency panels that are inexpensive enough to cover a roof. So, in the long run, you are right that space will be the overriding factor, but right now it's cost-per-watt that is the biggest problem.

Re:Is efficiency the problem?

[Anonymous Coward]

One of the difficulties that may prevent this as that some of the materials required for these systems have undergone quite considerable asset inflation - rare earths, copper, etc. This is partly because reserves of these elements are dwindling, partly because the machinery to mine them relies on machinery powered by oil derivaties which are more expensive, and partly because high global liquidity and low interest rates has led to a possible asset bubble in a number of assets. If cost drops to that of a car in 2008 then increased demand will then cause those raw materials to increase a lot in price, in which case the cost will then go up meaning a price of more than a car in 2009.

This is one of the big challenges facing us - a combination of some raw materials being in short supply (and thus high cost) at the same time, coupled with asset inflation due to other reasons. In some instances the high price will bring in investment to create new mines to create new supply, but this will take a decade or more (assuming new supply is possible). The problems at hand of energy security and of reducing climate change is one that needs to be invested in heavily on a more urgent timescale. If demand drives above supplies of the raw materials and the cost of the raw materials becomes 'real' (i.e. the element due to global liquidity asset price inflation vanishes) and this feeds into general inflation, then interest rates might be stubbornly high which makes long term investment in these technologies more expensive.

In other words the time to have really pushed forward on implementing many of these technologies would have been a decade ago, even with less mature technologies, as the economic conditions were more benign between then and now than they are likely to be between now and 2017. The technologies are still needed, but things will be tougher. The lowest hanging fruit need to be identified and identified quickly.

no

[wizardforce]

Suppose I just dump a bunch of Algae in a pond, then scoop off the top flotsam once a week, dry it in the sun, and then burn it? Would this be more or less than 40% efficient?

not even remotely. plants are efficient at converting photons to an immediate energy source but the vast majority is used to keep the existing tissues alive and functioning. esimates I have seen for the efficiency of converting light, CO2 and water into biomass ranges from less than 1% to 5% depending on the species.

Re:Cut to the Solar Chase: Nuclear Reactions.

[QuoteMstr]

Nuclear power production produces a lot less waste than coal mining alone does, and that's not even counting the radioactive dust that coal power plants spew into the air.

The Russians cut stupid corners in nuclear power. Not only did they use a graphite-moderated reactor at Chernobyl, but according to your linked article, they didn't glassify (or recycle) their nuclear waste. Furthermore, I doubt those rods have a high enough concentration of plutonium to actually explode. The article was a little light on the technical details.

Also, waste is not "just so dangerous." By the very definition of half-life, the most intense radioactive waste is the stuff that breaks down the fastest. That's why we keep it in cooling ponds for a few years before doing something else with it. After the high-radioactive components have decayed, what's left has a very long half-life, which means that it has a low level of radioactivity.

Besides, if at that level of radioactivty, you feel the need to manage waste for 10,000 years, how about managing our copper and gold mine tailings, which are killing our rivers? Or how about managing our toxic chemical waste, repairing underground gasoline tanks, cleaning up rivers that are so toxic that we can't eat fish out of them, and so on? What makes low-level nuclear waste more important than these more pressing problems?

And as for accidents -- all industries have accidents. A chemical plant caught fire a few years ago and poisoned hundreds. But look at it this way: we only have two choices for energy for the next hundred years: coal or nuclear. Even if we do have a nuclear accident or two (which is highly unlikely, given the paranoia surrounding regulation of nuclear facilities), nuclear power would hurt and kill fewer people than coal will.

Also, France uses nuclear power for 90% of its electrical needs. When's the last time you heard of a problem at a French power plant?

Re:Studebaker Nuclear Reactors

[thisissilly]

Solar, at 40% efficiency would still require covering something like 8% of the land surface area of Earth to meet current-day demands.

You might want to re-check your calculations. Total world energy usage is ~15 TW. Light at surface averages ~342 W/m.

Land surface is 148,939,100 km

(1.5*10^13 TW / [0.4 *342 W/m]) / 148939100000000 m = ~ 0.07%. Let's double it for extra capacity (and because half the planet is in night), and we're still under 0.15% of the land surface area. Your 8% estimate is large by a factor of 50 or so.

Of course, putting the whole thing in space might make more sense. If you really want pie-in-the-sky thinking, covering the moon with 10% efficient solar cells would provide about 86 times the power the world uses now. Getting it all back to Earth would be the tricky part.

Though I also agree we should be using better nuclear reactors.