Solar Power Becoming More Affordable 355
prostoalex writes "With both startups and large companies such as Boeing working on solar power, the technology is becoming more affordable, MIT Technology Review says. Solar power concentrators are all in rage now: 'The thinking behind concentrated solar power is simple. Because energy from the sun, although abundant, is diffuse, generating one gigawatt of power (the size of a typical utility-scale plant) using traditional photovoltaics requires a four-square-mile area of silicon, says Jerry Olson, a research scientist at the National Renewable Energy Laboratory, in Golden, CO. A concentrator system, he says, would replace most of the silicon with plastic or glass lenses or metal reflectors, requiring only as much semiconductor material as it would take to cover an area the size of a typical backyard. And because decreasing the amount of semiconductor needed makes it affordable to use much more efficient types of solar cells, the total footprint of the plant, including the reflectors or lenses, would be only two to two-and-a-half square miles.'"
Re:The Forever Headline (Score:5, Informative)
It's already happening in California. This deal is huge. It's between 300 and 900 Megawatts. [signonsandiego.com] And what's even more remarkable is that there is no federal or state funding for this project - not even a subsidy or tax break!
The solar electricity is simply profitable. Watch this closely.
Another interesting run is the Solar Tower project in Australia [enviromission.com.au]. I'm really excited by this one! Once built, the operating costs drop to near ZERO.
What few people realize is how much the price of electricity varies. So go get your utility bill. Call the nearest solar energy installation guys. You may find that it's profitable RIGHT NOW to put solar cells on your roof!
Energy Innovations (Score:2, Informative)
Re:Talk About Global Warming... (Score:4, Informative)
-you increase the overall efficiency of the system (up to 80-90%) by getting both electricity and heat
-you heat water while cooling down cells, which improve their efficiency too (you can get as much as 30% with germanium)
http://www.solartecag.de/sites/innovation.htm [solartecag.de]
Re:This is why Solar isn't taking off! (Score:2, Informative)
Ok, one last time hydrogen is a carrier of energy not a generator. H20 -> H2 into whatever storage device -> H20(exhaust frm fuel cell) not really going to gain a ton of energy. Sure it's relatively clean(although you are turning a bunch of liq H2O into water vapor) but hydrogen has energy density problems that need to be solved. So basically, stop getting your science info from Keanu Reeves [imdb.com] movies.
Re:The Forever Headline (Score:5, Informative)
Just a nitpick, really. I'm also quite excited about that project.
=Smidge=
Re:The Days of 100% ... exactly how? (Score:4, Informative)
Actually, a heat pump is a bad example, since you're putting energy in to move heat, not moving heat and getting energy out. With an engine, the amount of heat moved always has to be greater than energy out. Same with a heat pump - you actually can move more heat energy than you put power in. Hence coefficients of performance greater than 1.
-b.
Re:Passive solar heating... (Score:4, Informative)
Re:The Days of 100% ... exactly how? (Score:5, Informative)
In solar cells, the point is that photons excite valence electrons across a barrier, giving them enough energy to create a current. There isn't really a classical analogy for this effect.
There's a limited discussion of solar cell efficiencies here, although it doesn't talk much about the underlying physics:
http://www.lbl.gov/Science-Articles/Archive/MSD-f
The upshot is, cells of a single type of material can only get up to about 30% efficiency, but we can stick several materials together to get past that barrier.
Re:Interesting use of the word ONLY (Score:3, Informative)
I know that in the roofing industry you can put down a membrane that complies with CRRC requirements and within a month it won't. Granted, we're talking about relatively flat horizontal surfaces but anything left outside almost immediately begins losing measurable reflectivity from dust and dirt.
Re:The Forever Headline (Score:5, Informative)
The R&D was federally financed. I've done some work on it myself.
One of the advantages of this technology is that it is not solar. It's thermal. An external "combustion" engine is used to drive the generating turbine, thus any source of heat may be used.
One of the problems with solar power is that it is unreliable; innately. Some sort of storage/backuup system must be available to go online at all times. By using a heat engine to turn a generator instead of direct conversion to electricity, when the sun goes down you can just throw some buffalo chips (or whatever) in the firebox. There's no need for a completely redundant infrastructure.
KFG
A little google search turned up $5/sq. foot (Score:3, Informative)
Simple modular lenses (Score:3, Informative)
These concentrating lenses do not need to be very complex at all. In fact they don't even need spherical curvature at all. What they need are angles. That effectively makes a crude, but adequate, Fresnel lens. With flat surfaces, they are also cheaper to make.
The original Fresnel lens design for lighthouses needed to work with a very small focal point, the light source, and beam that light very straight. Thus it needed that spherical curvature. Even in its varies steps or layers, that sperical curvature still exists. Solar cells, however, do not need this.
Suppose you have a small solar cell module that measures 10cm x 10cm. Place it at the center of the back of a larger 50cm x 50cm box with the front aimed directly at the sun. Over the front of the box place a 5x5 grid of 25 openings, each the size of the solar cell. In the center, only a flat piece of plastic is needed. Outward from the center, a piece of plastic that is angled like a thin prism would be placed to bend the light at the necessary angle to hit the solar cell at the back. You'll have to figure out the right angle based on how deep the box is. But you will only need to have just a few different kinds of angles to complete the construction and concentrate almost 25 times the light onto the solar cell. Solar cells even operate more efficiently on concentrated light levels.
The box will need to track the sun to keep the various angled beams focused on the solar cell.
An alternative design is a box that is wider in one dimension and has open sides in the other. Stack multiple boxes with the wider dimension vertical so their open sides mate with each other. Tilt the stack to the angle of the sun's path and aim it for about the noon sun position. Then the morning and afternoon sun will be at an angle that lens light from one of these narrow boxes go through the mated openings and hit the solar cells of the adjacent box. You only lose what would be at the ends but you don't have to set up a steering mechanism.
Variations of these designs use mirrors instead of lenses to concentrate light. I personally favor the mirror designs using non-imaging reflective topologies. The same methods are also used for water heating.
Also consider using a water heat collector behind the solar cells. They do get hot (they aren't 100% efficient, so the energy is wasted somewhere).
Demonstration plants? (Score:3, Informative)
Re:The Days of 100% ... exactly how? (Score:3, Informative)
I once heard a mechanic say "You can just think of an engine as a glorified air pump" (a really dirty one)
The point is you just have to change how your looking at it. To see a heat pump as a generator, look at hot air on one side as fuel being burned (with colder air being the exhaust output) and hot air on the other side as the output energy.
Actually it has 2 fuels... the electricity comming in too. So it burns electricity and hot air, and makes hot air on the other side.
An air conditioner is just a heat pump where you hang out inside the "spent fuel tank". Its kind of like an engine with no alternator so it needs an external power source to spark the gas. And instead of hooking up a cam shaft, transmissions and wheels, you just pump the exhaust into the room to keep warm (finding the problems with that plan is left as an exercise to the reader)
-Steve
You CAN store it, though (Score:2, Informative)
The best thing about solar, though, is that peak demand is in the middle of the day...when solar is generating the most it can. So you just flip the system around. Use storage methods like on Taum Sauk to stockpile nighttime power to pick up the solar shortfall then.
Re:Solar Power still Useless (Score:3, Informative)
Power grids supply a mixture of peak and base load. During the day in the summer here in Australia a lot of the peak load goes to supply commercial aircon systems which do scale the same way as solar power systems.
You may need to bring your peak load generators (gas powered, usually) on at night but there is still a net gain from having solar power.
Re:Solar Power still Useless (Score:3, Informative)
The first thing to remember is that people usually go down when the sun does (give or take). During the day, when solar power is producing the most, people are up and running, working in their power hungry manufacturing plants and cubicle farms. That's when we need the most energy, so when it comes time to decide whether to build a new coal-fired plant, and it's only needed to handle peak capacity, rather than baseline, then solar is a great alternative.
The next thing to remember is that we have an electrical grid that can shunt solar power thousands of miles from where it's being produced. If it's cloudy one day, you can often get energy from elsewhere. Nor does solar power disappear "randomly". It disappears once a day. Solar continues to produce when it's cloudy, just at a reduced output.
Also, windfarms have a completely different energy production profile. Solar can produce power when it's not windy, and wind can produce at night. Taken by itself, this doesn't ensure a reliable supply, but when you realize you're working with numerous, geographically distributed installations, the picture becomes rosier. Throw in LNG power plants (which are supposed to be able to turn on and off much faster than standard plants), and I would guess you have a pretty viable system.
Finally, if we're overreliant on solar, nighttime electricity will become more expensive, and the market can adjust for that. For example, replacing old streetlights and domestic lightbulbs would eliminate a lot of need for nighttime energy. High performance computing clusters could shut down at night. People could turn of the television, sit down with their kids, and hit them.
Re:The Forever Headline (Score:3, Informative)
There are subsidies for solar power. However, traditional solar mechanisms are simply very expensive to operate. They require significant tracts of land, they use equipment that requires specialized knowledge to repair, and the output varies dramatically.
Don't we spend about that much per day in Iraq? I think we can spare a bit to remove our reason for being there.
A bit? At 200MW for 38km^2 (a 4km diameter), it would require (50000MW/200MW) * 38km^2 = 9500km^2 just to cover California's summertime requirements, and that doesn't account for the land in between. Winds may be an issue in the area, and anyone who has tried to build in California knows just how sensitive environmentalists are in this state. If you tried to cover up that much land, you'd have a major fight on your hands.
And what if it costs more than $200M? What if it costs double? When you factor in land costs in California, that starts to get very ugly. The output isn't proven, either; it may be 200MW, it may be 100MW actual output. Nothing has ever been done at that scale, and it's taking a lot longer than expected to get things in motion. I'm all for a trial spot, and if Australia wants it to be in their backyard, that's fine by me. In the meantime, if solar is a preferred route, I'd rather see more efficient means pursued, such as the Stirling generators.
Re:Solar Power still Useless (Score:5, Informative)
Power storage for solar can come in many forms. For a solar-thermal system (i.e. a stirling engine generator) you can simply store the heat using one of many mediums. For a photovoltaic system you can store the power using batteries, capacitors, hydrogen, heat, or even gravity by pumping water uphill. While the last three require a hybrid power system to access the stored energy (PV->H2/heat/gravity->electricity) they are not new technologies. In most areas you won't want a single power generation system so you'd have multiple plants anyway. The solar-thermal systems are particularly compatible with stored power as they work under direct solar energy, stored heat, or any combustible fuel (coal, wood, ethanol, petroleum, etc). And a solar/hydrogen power plant would double as a power source for hydrogen vehicles.
While it is true that areas closer to the equator see more power generation capacity from solar, even areas farther away still benefit from solar's ability to mitigate peak demand in summer and winter.
The cost of solar (PV or thermal) eliminates the almost incalculable secondary costs of conventional fuels (impacts on asthmatics from particulates, acid rain, ecological damage from mining coal or spilling oil, etc).
Re:Solar Power still Useless (Score:3, Informative)
That's utter nonsense.
First off, solar doesn't NEED to be stored. You can use it when it's being generated, and replace along the lines of 50% of fossil fuel power plants. Hydro electric handles 30% of all power needs in California, so here that would leave just 20% to be powered by wind, tidal, nuclear, or existing fossil fuels (coal/natural gas).
And besides that, there are numerous, highly effecient means of electricity storage.
Pumped storage hydroelectric is on the order of 80% effecient, and that is mostly limited by evaporation. Underground resivors would improve that greatly.
Flywheels have effeciencies around 90%, and inital investment can be done in steps/scale, as opposed to hydro.
Both can easily suppliment solar supply during high peak demand, in addition to acting as energy storage for nighttime.