Those of us that experienced Texas’ early summer heat wave can attest to the abundance of solar power as a renewable resource. The additional need to crank down the AC has put a substantial strain on the grid, surpassing the one seen during winter storm Uri last year which caused statewide blackouts – 75 gigawatts was used on one of the hotter Sundays in June, according to Ella Nilsen for CNN. She also mentioned that 40 percent of the power needed was generated from wind and solar (27 gigawatts), so solar was a major contributor to the grid’s ability to persevere despite extreme temperatures.
According to the Department of Energy, solar energy reaches the southwestern United States to the highest degree, making it the most efficient place to harness its rays – a fact with which southwestern residents will certainly agree! When harnessed, solar radiation or electromagnetic radiation, produced by the sun can be utilized to create advantageous types of energy like heat and electricity.
The U.S. champion of solar power is California which, according to CNBC, has 23 GW of installed solar power capacity. Solar makes up over 26 percent of California’s overall electricity generation. One of the larger solar farms in the state is the Topaz Solar Farm (Santa Margarita, CA), which is a photovoltaic facility that can produce 550 megawatts of electricity. According to First Solar, it produces enough electricity to power 160,000 homes. Ivanpah Solar Electric Generating system is a concentrated solar power project located in California’s Mojave Desert that generates 392 megawatts. That’s enough electricity to power 100,000 homes. California loves this clean energy source and has the generating capacity to prove it!
Solar power can be transformed into electrical or thermal energy. As far as renewable energy sources go, it is the most copious and the cleanest. It can be used for many things including: heating for interior environmental air and water, providing light and generating electricity, and it is harnessed using three main technologies: concentrating solar power, solar cooling and heating and photovoltaics.
Photovoltaics get electricity directly from the sun by using semiconductor materials. When these materials are hit with sunlight, electrons break free from their atomic bonds and can be guided through a circuit and used to power the grid or specific electronic devices. This is not the most efficient method because, according to the Solar Energy Industries Association (SEIA), only some light waves on the spectrum can be absorbed, others create heat (ultraviolet) or are reflected or too weak to create electricity (infrared).
Solar heating and cooling use the heat from the sun’s thermal energy to provide pool heating, cooling, hot water and space heating. With all of its applications, there is a big market for this renewable resource. According to the SEIA, in three to four years people will receive the return on their investment for installment of solar heating and cooling – a rather quick turnaround!
There are three elements comprising solar water heating technology: a hot water storage tank, insulated piping and the solar collector. Heat is transferred to potable water by the solar collector which is directed into a hot water tank and used as needed. In colder climates, an antifreeze solution is heated by the solar collector, and using a heat exchanger, it flows through the hot water storage tank and heats the potable water. Then the antifreeze flows through a pipe back to the solar collector. Another method is “drain-back” in which water is heated and flows to the portion of the building that requires it, then the water flows back to the solar collector by means of gravity.
Solar water heating collectors come in several types: evacuated tube, integral collector storage, flat plate, concentrating and thermosiphon. The most common is the flat plate in which copper plates are attached to an absorber plate inside of an insulated box coated in polymer or tempered glass. Evacuated tube collectors are made of rows of parallel, clear glass tubes that have had the air removed which makes them more effective at heating the liquid that runs through the tube. These are used when elevated temperatures or a larger amount of water are needed.
Additionally, there is technology that combines thermal and photovoltaic (PVT), which can heighten the electrical production by 20 percent. It uses solar electric panels on one solar module to heat water and create electricity. The most common type of PVT provides thermal energy and uses and cools the electrical photovoltaic parts which improves the output of electricity. PV alone only generates a quarter of the electricity that PVT panels can. Solar air heating is used for space heating and agricultural drying. Perforated solar panels are installed several inches from a wall which creates a space filled with air which is 30 to100 degrees above the outside temperature and through a connection to the HVAC tank which is ducted into the building.
Concentrating solar power uses mirrors to direct solar radiation to power engines or steam turbines to create electricity, and the energy can be stored and used to create electricity whenever it is needed. There are four types of concentrating solar power systems: parabolic trough, compact linear fresnel reflector, power tower and dish-engine. The energy can be stored and used to create electricity whenever it is needed. Parabolic trough systems utilize curved mirrors to direct solar radiation onto a receiver tube that goes through the middle of a trough and is filled with a heat transfer fluid. Once it reaches approximately 750 degrees, it heats water and the resulting steam turns a turbine to produce electricity.
Compact linear fresnel reflector systems also use curved mirrors, but they are paired with inexpensive, lengthy, flat mirrors. These mirrors heat tubes filled with water and, once boiling, can be used for industrial steam applications and power production. Power tower systems use heliostats (mirrors controlled by a computer) to follow the sun along two different axes and direct the radiation onto a receiver which then heats a transfer fluid to create steam and power a generator. Dish engine systems involve mirrors that are spread across a parabolic dish surface to focus light onto a receiver that then heats a working fluid to around 1,200 degrees and is used to power an engine.
The power of the sun can be harnessed and used for our benefit in many ways with no harm to the planet. It has helped rescue the grid in Texas, keeping us safe during the unprecedented temperatures that this summer has brought our way, and already makes up a large percentage of California’s electricity generation.
In April of this year, California reached a historical milestone when it was powered for nearly 15 minutes by 100 percent clean energy (that figure was later adjusted by California Independent System Operator (CAISO) to 99.87 percent). Reportedly, two-thirds of that was provided by solar power with the remainder coming from wind, geothermal and other renewable sources.
Prior to release of the corrected figure, Environment California state director Laura Deehan was quoted as saying, “California has shown that, for one brief and shining moment, we could do it! Now we need to get our state running on 100 percent clean energy for the whole day, the whole week, and the whole year. It’s time to move to 100 percent clean energy, 100 percent of the time.”
Headline photo courtesy of Marc Morrison ©2021 www.marcmorrison.com.
Shannon West graduated with a Bachelor of Liberal Arts in Psychology from Texas State University, where she developed a knack for writing research papers and case study analyses. After years of helping friends edit their university papers and cover letters, she is now putting those skills to use by copy editing and writing here at OILWOMAN Magazine.