Posting in Energy
Solar concentrators aim to increase the efficiency of solar energy generation and a new journal includes features on devices that concentrate the sun's rays.
A new research publication, launched less than a week after Earth Day, focuses on the impact of light engineering on the environment, green technologies and sustainable energy development. A bi-monthly supplement to Optics Express, the journal of the Optical Society, Energy Express will cover topics from making solar energy economical to providing energy from fusion.
The inaugural issue is dedicated to solar concentrators -- a technology that harnesses the most abundant source of energy available to us: the sun. Solar concentrators aim to increase the efficiency of solar energy generation and the journal includes features on new devices that concentrate the sun's rays and increase the efficiency of solar cells.
Despite its promise, solar power only accounted for about 1 percent of U.S. renewable energy production in 2008, according to the society. Because one of the greatest barriers to popularizing the use of solar power is its cost, industry experts are looking for ways to make its large-scale production cheaper.
How can solar energy become more affordable? By lowering the cost of solar cells or increasing the amount of power they generate, according to the Optical Society. Here are two of the methods, outlined by experts in Energy Express, which could achieve those goals:
The latest and most efficient solar cells in the National Renewable Energy Laboratory can achieve efficiencies greater than 40 percent while commercially-available solar panels are currently about 19 percent efficient. The best solar cells could reach 50 percent efficiency with more work, according to the laboratory's Sarah Kurtz and John Geisz.
Concentrated solar energy can be used to produce clean chemical fuels for the power and transportation sectors, according to Aldo Steinfeld of ETH Zurich and Alan Weimer from the University of Colorado. Thermochemical processes that make use of concentrated solar radiation as an energy source to drive high-temperature endothermic reactions have the potential to achieve high solar-to-fuel energy conversion efficiencies.
Image: False color image showing Earth's solar energy absorption / NASA
Apr 27, 2010
MIT demonstrated a portable solar collector a few years back that was unique. It looked like a standard satellite dish except the surface was mirrored. It had a self-contained system that boiled a liquid to make steam that turned a small turbine to make electricity. The theory says it is more efficient to have a stand-alone unit instead of a big convention setup. It is quite simple when you think about it. It takes less energy to heat a medium in a small closed loop than trying to pipe together hundreds of panels and heat all of that plumbing. It is simpler to motorize and manage one dish tracking the sun compared to synchronizing hundreds of panels to reflect to a central focal point. If the units are setup in groups it is easier to pool the power created than pipe hot liquid to a central turbine. It also makes the system redundant in that there is no single point of failure. Stand-alone units also make power station construction easy with simple foundations and a simple grid tie in. Another benefit of an efficient design is the infrastructure is less damaging to the environment. Beyond making solar power stations easier to build the stand alone systems would be perfect for people like me who do not want to lose the protection of shade trees and wind breaks on their house, but have sunny lawns that a self contained solar unit can be set on. The design of the units makes it an evolutionary design. As components need routine replacement it would be easy to swap in a new turbine or fluid pump that is more efficient to squeeze out another few watts of power. The designers even put a small PV panel on the back of the focal point collector to utilize every bit of sun hitting the unit. The panel charged a battery that powered the motor used to rotate the dish. The same battery started the fluid pump based on a temperature sensor that indicated the sun hitting the unit was warm enough to operate the unit. Making each home self-sustaining and a contributor to a larger pool of energy is a great goal as part of a truly smart grid.
A 6 1/2 year payback time is an over 15% return!! If you could consistently get that in the stock market (or any investment) you would be considered a genius! I would say anything less than an 8 year payback is a great investment. If you know of anyorjin krem let me know!
Solar concentrators work well where you can use a 2 axis tracker and you have a lot of direct sunlight. That is about 1/3 of the US, mainly the southwest and about 90% of Australia. Ironically Germany which has a huge solar program has pretty bad sun, equivalent to Seattle. There are already multiple concentrator companies that have achieved grid parity or better. Among them are Sol Focus (www.solfocus.com) and Amonix (www.amonix.com). The Rainbow Concentator by Sol Solution also looks promising.
A 6 1/2 year payback time is an over 15% return!! If you could consistently get that in the stock market (or any investment) you would be considered a genius! I would say anything less than an 8 year payback is a great investment. If you know of any let me know!
One problem with using concentrators on solar cells is they now have excess heat. But, the University of Utah has a patent on a simple device that takes heat, converts it to sound and converts that to electricity. So, you could take the excess heat off of the solar cell and feed it into the output as power. The devices were designed in the physics department originally as heat sinks for CPUs on laptops to extend their battery life.