The sun-blasted wilderness of the US Southwestern deserts may hold the key to our energy future. Stirling Energy Systems (SES) has found a way to turn all of that sunlight and heat into electricity. According to them, their system is twice as efficient as the best photovoltaic cells available.
Stirling Energy Systems builds a system that focuses the heat of the sun onto a proprietary engine that uses a closed hydrogen system to produce electricity.
Where traditional photovoltaic solar generation uses only 15% of the sun’s energy at best, the Stirling system converts 30% of that energy into electricity. The system is composed of a 37-foot diameter dish of mirrors that focus the sun’s light onto a Stirling engine.
The engine contains hydrogen which when heated expands, moving pistons, which turns a flywheel that is used to generate electricity. The hydrogen is not depleted in the process and so never needs to be replenished. The dish turns throughout the day to follow the sun. At night and on cloudy days, you need batteries.
Sandia National Labs Solar Thermal Designated User Facilities
These systems, due to their size and cost, are intended for industrial use only. Don’t expect to put one in your backyard unless you have a spare 58 square feet.
from their website:
Stirling Energy Systems holds two key patents on the solar concentrator system that were initially filed by McDonnell Douglas (by virtue of a merger, now The Boeing Company) to manufacture this solar concentrator system, as well as six of the original solar concentrator systems that were fabricated in the 1980s. SES also acquired all of the intellectual properties, including significant trade secrets regarding technical and manufacturing aspects of the solar concentrator system. SES was granted an licensing agreement with Kockums, a major Swedish defense company, to manufacture, market, and sell the Kockums 4-95 Stirling engines.
Right now a dish costs less than half a million dollars. As production ramps up, one of these units will be in the $150,000 range. A single Stirling set-up can power eight to ten American homes.
Stirling systems also have a minimal impact on the environment. They require antifreeze, lubricant, and someone with a squeegee and plenty of windex to go out there and clean off the mirrors. Actually, they use water, not windex. They might not use a squeegee.
The overall effect on the area around the dish is about the same as planting a tree. A shiny, noisy metal tree. A Stirling engine emits 66 dB of sound – just under the 70 dB at which hearing damage may start. But no smoke!
This method of generating electricity is called “solar thermal†or “concentrating solar†power. A solar thermal farm 100 miles by 100 miles could satisfy 100% of the America’s electricity needs.
BusinessWeek erroneously states that 100 square miles of dishes would satisfy US energy needs. They are not so good at math – it actually comes out to 10,000 square miles.
Is it cost effective? Hard to say. Stirling Energy Systems will not reveal the cost of generation. They do say that the dishes now cost about a quarter million each to produce. Southern California Edison (SCE) has entered a deal with Stirling to buy electricity at “well below the 11.33 cents per kWh†they are now paying for fossil-fuel generated electricity.
However, a 2003 study showed that the average cost of electricity from a Stirling dish would be 15. 37 cents per kWh. They are offsetting this cost by selling dishes.
Stirling has 20-year contracts with Southern California Edison for 500 megawatts and San Diego Gas & Electric for 300-900 megawatts.
Large view of the solar engines from above
High resolution images of the maps
sources
- BusinessWeek, September 12, 2005
- Stirling Energy
- California energy cost study (pdf)
- US DOE Energy Efficiency and Renewable Energy
- Sandia National Labs Solar Thermal Test Facility
Great Idea. To bad about the noise problem.
Stirling Engine Solar System Claims 30% Efficiency
Photovoltaics only get 15%. Link….
Depending on frequency of sound, some sounds cause ear ringing problems at lower decibels according to modern research. Do any of you have this problem being around people that click their gum? I do. I use to thing it was my blood pressure and salt but 10 out of 10 times it happens when I’m around irritating high pitched sounds.
“Don’t expect to put one in your backyard unless you have a spare 58 square feet.”
Bleh, comment system, here goes again:
“Don’t expect to put one in your backyard unless you have a spare 58 square feet.â€
How is that an argument against non-industrial use, that is 6 by 10 feet. The noise, the cost and the absolute clear sky requirement are the arguments for that, I reckon?
What about if it read “Don’t expect to put one in your backyard unless you have a spare 58 square feet and no neighbors with hearing to damage.â€
It’s an argument for commercial use in my opinion.
OK, admittedly I was looking at my non-existent backyard when I was considering Sterling Dishes for individual use. I did ask Donna McPeek of SES about neighborhood use (imagine one dish for every 8-10 houses in a new sub-division) and she replied with: “We are currently focusing on utility scale production; “home versions,” as you call it, are not in our immediate plans.”
As to hearing damage, the lowest threshhold is 70 decibles. You’d have to stand next to that all day every day for several months in order to start to damage hearing. So it’s not the sort of thing I’d want under my bedroom window.
Thanks so much for the feedback!
Tricia
70 dB is the loudness of a vacuum cleaner, not exactly hearing damage level.
I suspect businessweek meant 100 miles square which is 10,000 square miles. Not very large.
It should be noted that land requirements of solar (PV or thermal) are very respectible when compared to traditional fuels such as strip-mine coal.
I hope the government is throwing money at this project. SCE pays 11.3cents/KwH for fossil based fuel. You and I are paying additional cents for increased medical care due to fossil based fuel (direct AND indirect medical care). You and I are paying additional cents for loss of productive agriculture due to acid rain from fossil fuel, And here is where I go out on a limb, you and I are paying additional cents in military and political capital to protect our right to have “inexpensive” energy. OOPPSSSS govt. will not want to throw money at this project. It will reduce the need for military and bureaucrats.
Second OOPPPSSSS Technology is Swedish. Kockums-95 Engines
[...] Ran has a great post on free (solar) energy, how much we need, and what its uses are. File this with my post on Puramaize, an article about Stirling Solar-Thermal Generators, super-efficient solar energy systems that, “due to their size and cost, are intended for industrial use only.” [...]
had the smarts to send a man to the moon in 69, why warn’t these generators developed 30 years ago?
If it is cost effective there will be no need for government to “throw money” at it.
As an aside, a nice side invention would be for these things to somehow self clean themselves. Shouldn’t be too hard.
These systems aren’t a panacea. Except for hydro, all renewables have problems of intermittency. In the case of solar systems, besides the day/night cycle, there’s the weather to consider, and then an annual cycle overlaid on all of that. Intermittent sources aren’t useful for producing baseload power, and can’t even reliably provide dispatchable (load-following) power either. Yes, you can average out some effects by interconnecting different areas, and yes, there is some amount of natural load-following characteristic to solar power since loads are highest during the day and during the summer. Still, without a good way to store excess power, utilities ultimately need to turn to something else at night or when seasonal and weather factors cut off solar generators. There’s no magic bullet for nightly power storage at the moment, and nothing that can ride through longer periods of reduced availability. It’ll cost money to keep a bunch of fossil plants operational but use them only part-time. Renewables such as solar thermal and wind could certainly help reduce our need for other energy sources, as could efficiency improvements. Utility experts, as well as the experience of countries such as Denmark, show that renewables could provide 20-25% of electric power needs with known technologies: the rest still has to come from somewhere else.
May I suggest to you a landscape in the state of Florida (lots of land, sunshine and plenty of available water)
I picture Power Towers and Dish systems covering mass acreage, Right next to these sunny marvels you have man made lakes of accumulated rain fall. 50% of the power towers and dish systems are grid connected for direct electricity usage. The other 50% send their electrical current into those water supplies and BAM! … Hydrogen generating plants.
The future of fossil fuels is DEAD! F em all!!! every last oil company on the planet. Oil wars are ending. H2O + Concentrated Solar is the future
http://www.infiniacorp.com/applications/tactical.htm
seems they allready have a competitor
[...] Solar Thermal [...]