Concentrating solar power with a Stirling engine

In January 2010, Teserra Solar and Stirling Engine Systems showcased the Maricopa Solar plant in Arizona. This is the first commercial project for the SunCatcher concentrating solar power technology designed and manufactured by Stirling Engine Systems.The innovative and highly-efficient SES SunCatcher is a 25-kilowatt solar power system which uses a 38-foot, mirrored parabolic dish combined with an automatic tracking system to collect and focus the sun’s energy onto a Stirling engine to convert the solar thermal energy into grid-quality electricity. Developer Tessera Solar has created a 1.5 megawatt power plant out of 60 SunCatcher solar thermal devices.

SunCatcher has a number of advantages including the highest solar-to-grid electric efficiency, zero water use for power production, a modular and scalable design, low capital cost, and minimal land disturbance. SunCatcher was designed and developed in America, through a public-private partnership with the U.S. Department of Energy. The SunCatchers unveiled at Maricopa Solar were manufactured and assembled in North America, mostly in Michigan by automotive suppliers.

Now that the plant is up, Stirling will be able to compare the results its gets from its Stirling engines from heliostat prototype power plants erected by eSolar in Southern California and BrightSource Energy in Israel as well as parabolic trough systems that have already been commercially deployed. Parabolic companies, BrightSource and eSolar collect solar heat on mirrors and use it to heat fluid. The warmth causes the fluid to expand, which creates pressure that gets exploited to crank a turbine.

The Company has publicly quoted a fully-installed cost for grid-scale plants of $2.8 million per megawatt.

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World’s largest solar project planned in Sahara

If just 0.3% of the Saharan Desert was used for a concentrating solar plant, it would produce enough power to provide all of Europe with clean renewable energy. That is why 20 blue chip German companies are gathering in July 2009 to discuss plans and investments to create such a massive project. Both the meeting and project are being promoted by the Desertec Foundation, which is proposing to erect 100 GW of concentrating solar power plants throughout Northern Africa.

The red squares in the map to the right represent the land area necessary to meet the energy demand of the world, the EU and MENA in 2005. The last square represents the land necessary for the proposed project to generate 100 GW of concentrating solar power. The project being proposed by Desertec would not all be situated in one location, but scattered throughout politically stable countries. Taken as a whole, the project qualifies as the world’s largest solar installation – 80 times larger than the PG&E and BrightSource project planned for the Mojave Desert. The power generated would be transported over high-voltage DC lines across the Mediterranean Sea to Europe, where it would supply 15% of the energy demand. The project is still 10-15 years from going online, but that’s why major players are getting started now.

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Dyeing for more solar power

The main impediment to the widespread use of solar power – clouds and nightfall aside – is the cost of the silicon cells that actually convert the sun’s rays into electricity. To keep the expense down, people have been searching for ways to minimise the size of solar panels relative to the amount of light they can harvest. Often, this is done using clunky pieces of kit called solar trackers, which tilt an array of mirrors so as to direct large amounts of sunlight onto small, high-performance cells.

An alternative now being tested is called the luminescent solar concentrator (LSC). Instead of focusing the sun’s rays on a cell, as a solar tracker does, an LSC first traps them, wherever they have come from, and then delivers them to the cell using what is known as a waveguide. No moving parts are involved. A group of MIT researchers using this technology believe it could boost a solar panel’s efficiency by up to 50 percent and formed a company, Covalent Solar, to develop the technology.

The team has spent two years identifying organic dyes, painted onto glass or plastic that can effectively concentrate the sun’s light onto solar cells, enabling them to produce more electricity from fewer cells. The dyes basically reflect the light (technically, it’s actually absorbed and then sent back out), so that some of it is trapped inside the plane of glass. With the help of a scientific principal called “internal refraction”, which is the same principal that keeps light trapped in optical fibers, the light bounces to the edges of the glass, which have been equipped with strips of solar cells that convert it into electricity.

Integrated into solar panels available today, the technology could potentially boost the amount of light the panels convert into electricity by as much as 50 percent so consumers would get more electricity for their money.

The company hopes the technology could be used for both rooftop systems and for large solar farms and even one day could be integrated into windows, where a greyish tint would let in 20 percent to 30 percent of the outside light, while simultaneously directing the light toward solar cells around the window’s edges. Covalent Solar expects to bring its first product to market in three years.

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Eskom rebates on solar water heating systems

Eskom has announced that they will now pay up to a 25% rebate on the installation of approved solar water heating systems directly to the consumer. This is a change from Eskom’s initial Solar Water Heating Programme, introduced at the beginning of 2008, and brings it into line with international practice.

This initiative forms part of a drive by government for renewable energy to contribute 10 000 gigawatt hours (GWh) of final energy consumption by 2013. Solar water heating could contribute up to 23% of this target.

Installing solar water heating systems can reduce your heating bill by as much as 70%.

According to Eskom the rebate system is not in anyway exclusive. The requirements of a supplier to sell systems that qualify for rebates are the following:

• Be able to offer a 5 year guarantee
• Submit documents, including public liability and company details
• Have system tested AND passed at the SABS for the following;
  • Safety
  • Mechanical
  • Thermal

For more information read here…

Solar Energy Boom in Spain

Spanish companies and research centers are taking the lead in the recent revival of concentrated solar power, as expanses of mirrors are being assembled around the country for concentrated solar plants. At the same time, Spanish companies are also investing in huge photovoltaic fields, as companies dramatically increase production of PV panels and investigate the next generation of PV.

Spain is already fourth in the world in its use of solar power, and second in Europe behind Germany, with more than 120 MW in about 8300 installations of PV. Within only the past ten years, the number of companies working in solar energy has leapt from a couple dozen to a few hundred.

Solar thermal power, also known as concentrating solar, works by utilizing the heat of the sun (unlike PV panels, which work on the principle of the movement of electrons between layers when the sun strikes the materials).

PV costs run nearly double that of solar thermal for a power plant of a similar size, but PV has the advantage of modularity.

Original article: Technology Review. Read more…