Ariz. Team Seeks Fossil-Fuel Cost Parity, Using Solar Energy Concentrators

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.'"

Comments

Which government subsidization?

[timeOday]

It's hard to count all the ways our oil economy is supported and subsidized by the government. And we haven't even started cleaning up the mess yet.

subsidization?

[polar red]

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)

Solar cells is a bad idea for concentrators

[BlueParrot]

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

[Waffle Iron]

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?

[tmosley]

A watt is a unit of power, a watt hour is a unit of work. The goal is $1/W which means that a 1000 W system, which produces ~8KWh per day (more further south), only costs $1000, and would pay for itself in about three years, making it economically viable for most people.

Re:Still the same problem as with all solar

[Aighearach]

If only somebody would invent some sort of device that could store electricity for later use.

Then I could finally ditch the diesel generator I have to drag around to keep my mp3 player running!

Re:Bullshit.

[Desler]

Yeah, those subsidies clearly don't exist. That's why at one point Obama claimed he was going to cut $36.5 billion in them.

Re:Bullshit.

[Desler]

And yet despite claims that they wouldn't miss them, they continue to lobby and fight against their removal.

Re:Still the same problem as with all solar

[jmorris42]

Look into the efficiency of a battery sometime. Unless you buy really expensive ones you lose about half of the energy putting it into and getting it back out. More losses if you are putting in AC and needing AC back out. And the really good (from an efficiency pov) lithium-ion batteries don't suffer many charge discharge cycles before hitting the 50% capacity point generally considered as replacement time. We currently have zero methods to store electricity that are cheap enough and effective enough for use on the grid. All electricity is generated as needed, with vast arrays of 'peaking power' generation capacity that largely sits idle. Believe me, if there were a good way to store electricity the industry would be using it already.

Worse, while electricity can be sent large distances, it is best to generate close to the point of use because of the line losses. So even if we were willing (and shot enough enviromentalists) to cover our deserts with solar arrays we would lose most of the power heating the lines getting it to where the customers are. Same for wind, it mostly occurs in areas where there aren't many people... or more accurately windmills near populated areas attracts more environmentalists.

Re:Still the same problem as with all solar

[cduffy]

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

[vlm]

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.

Re: the clean West

[presidenteloco]

"We in the West are pretty clean for the most part - it's getting India, China and other developing countries to clean up..."

What the hell are you smoking? Or more aptly, what planet are you living on?

A person living in China is responsible for 17% as much greenhouse-gas emissions as is a person living in the United States.
A person living in India is responsible for 8% as much greenhouse-gas emissions as a person living in the United States.

http://en.wikipedia.org/wiki/List_of_countries_by_greenhouse_gas_emissions_per_capita

and that's not even accounting for the fact that much of the most polluting parts of the Chinese and Indian economies are devoted to supplying the West with goods.

Re:okay, makes sense now, thanks

[DarkOx]

Wow, umm no.\\

Go back and check your history. Edison LOST that argument with Tesla. Tesla wanted AC because it was better for running motors and was more efficient for long distance transmission. Edision wanted DC because its arguably safer.