Since the early 1960s, when the French engineer and inventor Auguste Mouchout used a sealed glass pot, a polished parabolic dish and the heat of the sun to create steam, Powering the first steam engine powered by “solar energy”, up to now, solar thermal energy (STE) technology has made great strides.
A wide range of technology systems are now available or ready to be used – including parabolic mirror troughs, power towers, and disc/motor systems – and several others in the pipeline. . The consecutive announcements that have appeared in October and November show the diversity and deployment level of these technologies.
NEW CSP TECHNOLOGY GENERATION
Ausra Inc. put into operation the Kimberlina Solar Thermal Energy Station (STE) at Bakersfield (California, USA). This is the first solar thermal power station since FPL Energy Company built nine solar power generation systems in the Mojave Desert in the late 1980s and early 1990s.The Kimberlina 5 MW power station uses “new generation” concentrating solar power (CSP) technology, as Ausra Inc. calls it, and the company says the power station was built. modeled after the Liddell thermal power station in the state of New South Wales (Australia). The station consisted of rows of 1,000 feet (300 m) mirrors, and it took 150 workers 7 months to build (see Photo 1). The energy harvesting lines will generate 25 MW of thermal energy to power a steam turbine at a nearby clean energy generating station. According to the company Ausra, they have reduced costs by simplifying design and mass-producing mirrors at their factory in Las Vegas (Nevada).
Kimberlina is just the beginning of solar thermal power in California. Ausra is currently developing for Pacific Gas and Electric a 177 MW thermal power plant at Carrizo Plains, west of Bakersfield. In addition to the plant, the California Department of Energy is reviewing proposals for five large solar thermal power plants, including Stirling Energy Systems’ SES Solar Two (750 MW) project, and a solar tower. BrightSource’s Ivanpah (400 MW), Beacon Solar’s (250 MW) solar trough project in Kern County, and two hybrid energy projects using solar collectors to generate a total capacity of 112 MW. These six projects combined will add 1,689 MW to the grid. The Federal Office of Land Management is also studying a request to invest in 34 more solar power plants in Southern California, with a total capacity of about 24 GW.
STEAM TUBE SUN TOWER
According to Siemens Energy, it will provide an industrial steam engine for one of the first commercially operated solar tower power plants, the company’s Solar Tres (19 MW) project. Sener company, located near Seville (Spain), started construction 7 years ago. To focus the sun’s light, this power plant will use a system of sun-tracking mirrors arranged in rows around the tower and reflect the light directly into a collector located on the top of the tower about 400 feet high (120 feet). m).
The sun-tracking mirrors (heliostat) will be arranged over an area of 0.32 square kilometers, which is about 60 times the size of a football field. In this project, salt is used to transfer heat inside the collector, instead of the traditional thermo oil. Concentrated sunlight will generate temperatures above 900°C at the receiver. As a result, the salt, when heated to about 565oC, will change to a liquid state and flow through the heat exchanger, creating enough steam to turn the turbine generator set.
Siemens, a manufacturer of turbines for use in solar thermal power plants using parabolic mirrors, has specifically built a two-cylinder reheater SST-600 turbine to meet the technological requirements for the Sener solar tower project. According to Siemens, the reheating will improve the overall efficiency of the plant. Siemens also worked with Sener to find a protection design to prevent the steam turbine from overheating at night.
PARABOL MIRROR WITHOUT GLASS
Most parabolic mirror troughs are made of very heavy bent glass. But SkyFuel Inc. newly established and scientists from the National Renewable Energy Laboratory recently revealed that SkyTrough is again made with SkyFuel’s own material called ReflectTech, a silver-plated polymer thin film with high reflective properties. , which is hard to break, is attached to thin aluminum plates (Picture 2). This thin film has several advantages: it allows the fabrication of larger fractional plates, and therefore less quantity required than previous mirror trough designs, and, according to SkyFuel, thereby reducing costs for the parabolic trough concentrates light up to 35%; and can be manufactured in large quantities.
Unlike other competitors in the solar energy sector such as Ausra and BrightSource, in negotiations with many companies intending to build solar thermal power plants in the southwestern United States, SkyFuel said. that they do not want to build their own power plants according to this technology. SkyFuel is also working on their own version of Linear Fresnel technology, which uses molten salt as the heat transfer fluid.
SOLAR COMBINED TECHNOLOGY
In October 2008, the US Electricity Research Institute (EPRI) began a research program at two natural gas-fired combined-cycle plants – the Griffith Energy plant of Dynegy Inc. in Kingman (Arizona) and NV Energy’s Chuck Lenzie power plant, near Las Vegas (Nevada) – to help power companies add solar energy to fossil fuel-powered power plants . As part of a larger study, in 2009, EPRI carried out a parallel study at coal-fired power plants, but the location of the study has yet to be determined.
According to EPRI’s argument, 27 US states have policies on renewable energy standards, of which some states set mandatory rates for solar energy. However, most solar energy applications are not yet cost-competitive with other power generation options. According to EPRI, using solar energy to support coal or natural gas could “be the least expensive alternative to adding solar energy to electricity sources because it uses existing electrical installations. yes. And because the strongest solar intensity generally falls during peak summer loads, this makes the solar-powered steam cycle a really attractive renewable energy option”.
According to EVN
