Ariz. Team Seeks Fossil-Fuel Cost Parity, Using Solar Energy Concentrators 245
autospa writes "A University of Arizona engineering team led by Roger Angel has designed a new type of solar concentrator that uses half the area of solar (PV) cells used by other optical devices and delivers a light output/concentration that is over 1000 times more concentrated before it even hits the cells. This comes as a result of a broader goal to make solar energy cost competitive with fossil fuels (target = 1$/W) without the 'need for government subsidization.'"
Solar cells is a bad idea for concentrators (Score:5, Interesting)
If you are using concentrators for solar power you really ought to consider a thermal cycle like a brayton turbine or a sterling engine, rather than solar cells. Thermal cycles tend to have higher conversion efficiencies, the equipment is more reliable, and their power output is more easily converted to grid voltage ( AC as opposed to DC ). Solar cells also tend to see reduced lifetimes when used with very concentrated light. The advantage with cells is pretty much that they don't need concentrators to work, since they don't rely on a high temperature. They can also be used in places where space/weight is an issue, such as on sailboats, rooftops or sattelites. Thus if you are already using a bulky concentrator to get the light intensity up, you may as well use a sterling engine.
Re:Solar cells is a bad idea for concentrators (Score:5, Interesting)
If you are doing a thermal cycle with concentrators, you need a *big* system. Small thermal engines aren't much more efficient than garden variety solar cells. (And presumably, concentrated solar would use high-tech cells that rival the efficiency of big heat engines anyway.) That means that you have to use a complex "power tower" arrangement with a field of precision synchronized mirrors pointed at one huge collector. You also need a big cold sink for thermal cycles; most power plants use a bunch of water for that, which is hard to come by in the desert.
The solar cell approach would also have the advantage of mechanical simplicity, and the ability to add capacity in small self-contained increments.
Re:What does $1/W mean? (Score:3, Interesting)
I pay about $0.10/kWh. (1000 W per Hour)
What it probably means is they're scammers. Capital costs for coal and nuke run from $1.50 to $3.00 per watt installed. They're claiming $1 per watt. The problem is no matter how unconventional the heat source, no matter how magically free, the employee lunchroom costs $ per plant, the parking lot paving costs $ per plant, the pipes from the magic heat source to the turbines costs $ per watt, the turbine itself costs $ per watt, the water pumps and filters cost $ per watt...
PERHAPS they mean the capital cost of their magic heat source alone costs about $1 per watt. The problem is some recent historical nukes (not in the backwards USA, but civilized countries like France, etc) have come in at $1.50 per watt total plant cost delivered. So, on one side, their costs probably will decline as they are new vs the very mature nuke industry. On the other hand, can you build an entire thermal electric plant for well under 50 cents per watt? Then again, can a new tech be nearly as reliable as ancient technology nuke plant?
Re:subsidization? (Score:0, Interesting)
without the “need for government subsidization.”
ALL sources of energy receive subsidy. some examples : Oil (how much did all those wars cost?), coal(damage to public health=hidden subsidy), nuclear(research since the forties)
It doesn't matter.
A couple of months ago in Scientific American, they interviewed a venture capitalist - I can't remember his name. Anyway, he had this very interesting point: we can't have subsidies on alternative energy. Why? Because the countries where it's imperative that they adopt such clean tech do not have subsidies nor can they afford them. So, if the energy cannot be cost competitive without subsidies then it isn't worth it.
Subsidize in the beginning until it does become profitable? If that were the case, then MAYBE. But the thing is, many of these technologies cannot scale or if they can, they do not become more cost effective.
We in the West are pretty clean for the most part - it's getting India, China and other developing countries to clean up and they don't have the money to subsidize any technology.
Any green tech that can compete with fossil even with their tax subsidies will win hands down. I think it is possible - probable.
Re:Still the same problem as with all solar (Score:5, Interesting)
If electricity is cheap in the daytime and scarce/expensive at night, the market will figure it out.
Maybe that means people have incentive to charge their cars at work. Maybe it means entrepreneurs buy excess electricity on the spot market during the daytime, use it to pump water uphill, and use the potential energy of that water to generate more expensive electricity at night. (Is that process lossy? Sure! But the market will only reward it if it provides a net benefit, so it's all good. Same for battery / ultracapacitor / other technologies -- if they're a good fit for the problem, someone will make money using them; if not, they won't).
Re:okay, makes sense now, thanks (Score:5, Interesting)
Direct current is almost impossible to transmit across any meaningful length of electric cable.
Humorously, you have it exactly wrong. The longer the cable, the (relatively) cheaper the cost of HVDC conversion gear vs the rest of the project.
The power delivered by a AC line is based on the RMS voltage. However you have to insulate to peak, which is somewhat more. Insulation is a pretty major design constraint, as arcs to the ground or towers is kind of a waste of power...
As a very rough guess on a medium length line you can push about 1/4 to 1/3 more power for the same cost if you switch to DC.
The power levels I'm talking about are a couple GWs, distances of dozens of miles, costs vaguely around gigadollars. Capital costs of about a buck a watt per 50 miles, lets say. You can see the motivation of placing plants nearby cities, rather than in the middle of nowhere.
You can do long distance AC, and they used to, it just costs a heck of a lot more.