by John Lawrence from the San Diego Free Press
This article is based on an excellent book by Tom Rand: "Kick the Fossil Fuel Habit - 10 Clean Technologies to Save Our World." It contains great information at a reading level that even an elementary school child can comprehend. And there are many superb pictures too. It is a wonderful resource in the numerous technologies that are in the process of ridding the world of fossil fuels - some of them hardly known to the literate public. At least I wasn't aware of them, and I consider myself somewhat knowledgable about global warming and what we can do about it. He identifies ten different technologies. We will devote an article to each of them. Part 1 will deal with solar.
Most everyone is aware of solar panels. The sun provides the earth with an enormous amount of energy which we are learning how to convert into energy to power our cars and our homes. A square yard of desert absorbs as much energy over a year as you can get out of a barrel of oil. In fact a barrel of oil contains energy from the sun that was absorbed millenia ago and stored as fossils. An area of desert the size of tha state of Connecticut absorbs enough energy to replace the entire oil output of the OPEC countries. The technology to convert this energy to power output useful to humans is available today.
Solar photovoltaics (PV), the solar panels that we put on roofs, is becoming increasingly prosaic. Currently they are made of silicon with more advanced materials on the way. Incoming photons from the sun knock electrons out of their orbits which are then sucked away by an electromagnetic field generating an electric current. The efficiency of this process currently maxes out at 25%. In other words 25% of the sun's energy striking the panel is converted into electricity. New designs are achieving as much as a 40% efficiency. The next gebneration of PV will be thinner, bendable and will be able to be incorporated into building structures. One day the shingles on our roofs will double as solar panels which will power our homes.
A California company called Carousol is manufacturing a device that tracks the sun, magnifies its light 625 times and focuses it on a next generation PV cell. Another company Morgan Solar also has a device to concentrate solar energy which could make solar energy far cheaper then coal.
The neat thing about PV solar is that the energy from the sun can be produced by millions of solar panels on millions of individual rooftops. It turns farms, homes and businesses into energy producing entrepreneurs. For instance, Germany is awash in solar PV. In 2007 alone enough solar panels were installed throughout the country to power more than 1.2 million homes. The reason is that the German government has given people an incentive to install them. It's called a feed-in tariff which allows individuals and businesses to sell energy so produced back onto the grid in such a way that it is profitable for them to do so. Here in the US lobbyists for the utility companies are fighting a similar plan because, when individuals and businesses not only produce their own energy but also sell the excess back onto the grid, the utility company loses the exclusive right to sell energy and their profits are diminished.
Other solar energy producing technoligies make use of concentrated solar power. There are three common ways of concentrating the energy from the sun - the trough, the tower and the dish. First the trough. Long lines of parabolic mirrors concentrate the sun's energy on a tube containing an oil-like fluid which heats to around 750 F. The fluid passes through a heat exchanger that draws heat from the oil and uses that heat to turn water into steam which in turn powers a turbine that generates electricity.
According to the website earthtimes.org:
California environment friendly legislation, that combines market based incentives as the proverbial carrot and regulatory requirements as the stick, have brought about a renewable energy boom. The world's biggest solar project, Mojave Solar Park, is located in Mojave Desert in California. This mega solar plant can generate 553 MW and covers 2300 Hectares, the power and land covered being the world's largest. The solar thermal power facility is being constructed for Pacific Gas and Electric by Solel Inc.
California's Mojave Desert is home to a number of solar projects. This one was contracted by Pacific Gas and Energy and should power half a million homes. Existing parabolic fields in the Mojave Desert at Harper Lake, Kramer Junction and Daggett have been in operation for years and are generating enough power for more than 350,000 homes thus reducing California's annual oil consumption by two million barrels. The materials for these projects - glass, metal, cement - are not exotic and are readily available so there is no reason why available desert land cannot just be built out with solar projects. When the Mojave Solar Project goes online, parabolic solar farms alone will replce 3.5 million barrels of oil annually.
Another example of concentrated solar power is the tower. Acres of parabolic mirrors focus the sun's energy at a huge tower. At the tower temperatures of as much as 4000 F can be achieved. Tubes inside the tower are filled with molten salt that carry the heat away. The molten salt heats water, creates steam and turns a turbine. The salt can also be stored and used as a battery thus powering homes at night.
According to solarenergy.einnews.com:
Located in Mojave Desert, on the border of California and Nevada, the Ivanpah Solar Power Facility represents one of the largest solar thermal energy facilities in the world.
The $2.2 billion project will deploy 170,000 heliostat mirrors which will focus solar energy on boilers located in centralized towers spread across the 4,000 acre facility. As the water in the centralized boilers begins to heat up, steam will be created and used to drive turbines that will generate electricity.
At its maximum capacity the Ivanpah facility will produce 392 MW of power, with annual generation estimated pegged at 1,079,232 MWh.
Although the Ivanpah facility has been connected to the California power grid, it’s still in it test phases and hasn’t begun adding power to the grid. However, experts agree the facility should be contributing to California’s energy demands by year’s end.
The third method of concentrated solar power is the dish. Stirling Energy Systems (SES) has developed the SunCatcher solar dish for utility-scale power plants. Its mirrored concentrator dish focuses sunlight on a high-efficiency Stirling engine that powers a generator to produce electricity. There is also a small scale version suitable for individual home and business use. The Stirling engine is an internal combustion engine that burns sunlight instead of oil. Unlike the internal combustion engine which harnesses the power of a controlled explosion inside the engine's cylinders, the Stirling engine uses heat generated from sunlight outside the cylinder to heat expanding gas.
The future of this technology, however, is in doubt. In 2011 SES filed for bankruptcy as the technology of solar photovoltaic outcompeted it on cost. Its projects in the Imperial Valley have been taken over by a succession of other companies after San Diego Gas and Electric (SDG&E) canceled its original contract. However, PV panels are currently being installed at the Tenaska Imperial Solar Energy Center South near El Centro, CA by First Solar. In 2009, First Solar became the first solar panel manufacturing company to lower its manufacturing cost to $1 per watt (since reduced to 68 cents per watt).
They announced in September that construction has started on the 150 MW AC Solar Gen 2 project, which will be the largest solar power plant First Solar has constructed, in Imperial County. Under a 25-year power purchase agreement between SDG&E and First Solar, the 150 MW project will generate enough clean energy to power more than 60,000 average California homes, displacing more than 115,000 metric tons of CO2 per year (the equivalent of taking 22,000 cars off the road) and saving 93,000 metric tons of water per year.
This energy will be delivered to SDG&E and will arrive in San Diego over Powerlink, the controversial transmission line that was energised about a year and a half ago. It has been charged that most of the energy delivered over Powerlink is generated across the border in Mexico by conventional greenhouse gas emitting means and that the solar plants are a minor part of the picture which have been developed for advertising purposes.
This is from kcet.org:
The transmission line has been marked by controversy since its inception. The most heated battle involved a proposed northern route for the transmission line, which would have cut through Anza-Borrego Desert State Park -- the state's largest park.
Some opponents claimed that the emphasis on renewable energy was intended to distract from the line's eastern terminus' proximity to two large gas-fired power plants across the border in less-regulated Mexicali. The Mexicali plants are owned by Sempra, SDGE's parent company, and are fed via Sempra's Gasoducto Bajanorte pipeline from the firm's Energia Costa Azul Liquefied Natural Gas (LNG) plant near Ensenada. Critics have alleged that the Sunrise Powerlink is really intended to carry electrical power from the Mexicali plants. SDGE has no legal obligation to carry only renewable energy on the transmission line, but has pledged never to use it to carry power from coal-fired plants.
This is from SDG&E's website:
Tenaska Imperial South is one of eight renewable projects SDG&E signed purchase agreements for totaling more than 1,100 megawatts (MW) of power in Imperial Valley that would be transmitted across the Sunrise Powerlink.
“The Sunrise Powerlink is the largest and most significant project in the history of SDG&E and we are thrilled that Tenaska is delivering its first energy from this project to our infrastructure,” said SDG&E’s senior vice president of Power Supply, Jim Avery. “SDG&E is a leader in the acquisition of renewable energy and our partnership with Tenaska is an important part of meeting the state’s clean energy goals.”
Currently, Tenaska Imperial South is producing approximately 40 MW. When the project is complete later this year, it will produce up to 130 MW, enough to power approximately 44,000 homes.
SDG&E and Tenaska have also contracted for a second solar project, the Tenaska Imperial Solar Energy Center West, which will produce up to 150 MW and is expected to come online in 2015.
The first renewable project to connect to the Sunrise Powerlink was Pattern Energy’s Ocotillo Wind Energy Facility, a 265 MW project located near the community of Ocotillo, in Imperial County. A portion of this facility was energized in December. Several more SDG&E-contracted renewable projects are under construction, or will be under construction soon.
Another company, Tenaska, is also in the mix. Evidently they have control over the Imperial County project and First Solar is just a sub-contractor of theirs. The plot thickens. On October 28, 2013, just a few days ago Tenaska announced that Prudential Capital Group (Prudential) has agreed to acquire a minority interest in the Tenaska Imperial Solar Energy Center South project, a 130-megawatt (MW) solar photovoltaic electric generating station near El Centro, Calif., currently owned by a Tenaska affiliate.
The potential of solar is huge. Solar thermal plants built on just 1% of the surface of the Sahara could provide the entire world's electricity demands. So why isn't it being done post haste? Because the issue of privatization vs socialization always comes up. Even though the earth's atmosphere is a commons which applies to all people everywhere and can't be privatized, renewable electricity generation which is necessary to save the planet from utter destruction from global warming is thought by many, but certainly not by all, to be in the domain of private enterprise. Since private enterprise is all about profit, the best way forward is not the best way to save the planet but the best way to make profits. If we can't resolve that conundrum, the planet may go up in smoke - not because the technology is not available - but because certain people put profit and the free enterprise system above all else.
After each chapter Tom Rand asks the question for each technology, "what would you get for $1 trillion?" His answer for solar? a trillion kilowatt hours per year or enough solar energy to replace half of the coal-based electrical production in the United States.
Next time: renewable electrical energy from the wind.