Solar_Power

In our fight against global warming we have many sources of renewable energy available Some of these renewable sources include the wind power, wave power, hydroelectric power, and biomass. But none of them have as much potential as solar power. To give an example of the potential of solar power, in just one day, the United States is struck with enough energy from the sun to provide for our energy necessities for the next year and a half. Although solar power has so much potential, according to the U.S Energy Information Administration, renewable energy only accounts for seven percent of total energy supply for the United States. Of that 7% solar power only accounts for a measly one percent, while biomass and hydroelectric power are our biggest renewable energy sources accounting for a huge fifty-three percent and thirty-four percent of total renewable energy output. Two big problems keeping solar power from being a truly revolutionary renewable energy source are our current inability to store this power when the sun is not shining and it's current high cost. For solar power to be a viable renewable source of power in the coming energy revolution, high costs must be addressed and a better storage solution found. To understand the troubles facing the storage of electricity from solar power we must first understand what solar power is. Solar power is generated with photovoltaic cells which convert the sun's radiation directly into electricity through chemical reactions with different materials such as cadmium, or the more common silicone. Photovoltaic cells are not only used for generating electricity for energy utilities, they are also used in everyday items such as calculators, watches, and various others. Solar power plants use very large arrays of photovoltaic cells to generate electricity the electricity needed by cities. These photovoltaic power plants must be built large areas of land in sunny areas of the world, such as southern areas of the United States, which could be considered a drawback by many critics. Despite this, many countries continue to try ton supply their people's energy needs with solar power. Many of the world’s largest photovoltaic power plants are located in Spain and Germany with some others across other countries like Portugal, Korea, Canada, and even the United States. The largest of these solar plants is the Olmedilla Photovoltaic Park located in Olmedilla de Alarcón, Spain. The Olmedilla Photovoltaic Park was built in 2008 and consists of more than 160,000 photovoltaic cells and generates about sixty megawatts of carbon free electricity, enough to power about 40,000 homes. The second largest photovoltaic solar plant is the Strasskirchen Solar Park located in Straßkirchen, Germany and built in 2009. It produces about fifty-four megawatts of electricity for homes and businesses. Although the United States is not a leader in photovoltaic power plants it does have one. The biggest photovoltaic power plant in the United States is the DeSoto Next Generation Solar Energy Center in DeSoto County, Florida. As of 2009 it is the largest photovoltaic power plant in the United States. It consists of over 90,000 photovoltaic cells taking up around 180 acres. The 90,000 cells are able to generate about twenty-five megawatts of carbon free electricity for homes and businesses around it. Compared to conventional coal-fired power plants solar power plants are much more expensive. According to the Federation of American Scientists, conventional coal-fire power plants cost upwards of 3 billion dollars to build while solar power plants cost only about one hundred million. But one must also take into account that the coal-fire power plant generates upwards of 600-800 megawatts of electricity while the solar power plant only generates about 14 megawatts. If the solar power plant was scaled up to generate as much power as a coal-fired power plant it would cost upwards of 5 billion dollars and use up massive amounts of land. A solution to this problem is addressed by Thomas Friedman in his book Hot Flat and Crowded. Friedman proposes sending a price signal from the government to dirty fuel power plants like a tax or floor price on dirty energy sources such as natural gas and coal. The price signal would serve as a guarantee to potential investors of solar power that a market will be there to purchase their new clean energy. And as a result of these price signals and new investments Friedman claims that these renewable energy sources will “benefit from learning curves. The more we use them, the more we move them down their cost-volume learning curves; they cost less, do more, and deliver more energy for less money.”(Hot, Flat, and Crowded p.300) Thus making solar power and other renewable energy sources cheaper for energy utilities and more affordable for consumers. Drawbacks of using photovoltaic cells in solar power plants to generate electricity are their high costs, and inability to generate electricity at night, or whenever the sun is not shining, thus the need for expensive, inefficient batteries. Batteries may be fine for storing solar power in home use, but when scaled up to energy utility proportions they become extraordinarily expensive. The most common battery used for storing this amount electricity are lead-acid batteries. These batteries decay over time and must be replaced about every five years because of their limited lifespan, but luckily, most of the components of the battery are recyclable. A possible solution to the storage problem solar power faces comes from the Michigan Institute of Technology: the invention of a new liquid battery that is said to be powerful enough to store solar electricity. This experimental battery was created by Donald Sadoway and his team of engineers. The battery is made up of of three liquids: molten magnesium, antimony, and sodium sulfide. Kit Eaton, from Fast Company magazine explains how this battery works: “When charging the battery, electrons are picked up by magnesium ions in the liquid, forming liquid metal magnesium and rising to the top of the battery. Meanwhile antimony ions lose electrons, and sink to the bottom as a layer of metal. This continues until all the metal ions are 'used up' so that the battery is fully charged and there's only a narrow strip of electrolyte. When it's being discharged, the chemical process inverts and pushes electrons out until the liquids are back in their initial ionic state.”(Solar Power Storage Solution: Liquid Batteries) These batteries do not decay like conventional batteries, it can charge up to ten times faster than conventional batteries because ions can move much faster in the liquid, and is cheaper than other conventional batteries because it is more simplistic in its materials and its design. A different possible solution to solar power storage comes from Daniel Nocera, MIT's Henry Dreyfus Professor of Energy. Nocera and his postdoctoral colleague Matthew Kanan have overcome the problem with large scale energy storage of solar power. Their method for energy storage was similar to photosynthesis; they stored energy in chemical bonds. They will use the sun's energy to split water into it's oxygen and hydrogen components which can later be combined again inside a fuel cell to create carbon free electricity to power homes and businesses. Anne Trafton from MIT news explains the process: “The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity – whether from a photovoltaic cell, a wind turbine or any other source – runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced. Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis. The new catalyst works at room temperature, in neutral pH water, and it's easy to set up.”('Major discovery' from MIT primed to unleash solar revolution) Nocera hopes that advances in his design can make it more practical in the next ten years. With these new innovations in energy storage clean abundant renewable energy does not seem so far away. Another much simpler solution to the solar power storage problem would be to use solar thermal plants. Solar thermal plants use large arrangements of mirrors that concentrate the sun's heat into a kind of receiver with a heat transfer liquid inside. Steam would then be generated from the super heated liquid and the steam would then be used to power turbines to make electricity. The industry has extensive knowledge of working with heat, so they know how to store heat better than electricity. John S. O'Donnell, vice president of Ausra, a solar thermal energy company, gave an interesting fact about energy: “a coffee thermos and a laptop computer’s battery store about the same amount of energy” but the “thermos costs about $5 and the laptop battery $150.” (Matthew L. Wald, New Ways to Store Solar Energy for Nighttime and Cloudy Days, NY Times) The idea behind these new thermal solar plants is that they will be able to store this heat energy like a dam, for many hours or up to days to supply towns and cities with electricity when, or in case the sun is not shining. These new solar thermal plants plan on using molten salt as a storage medium for the heat. Molten salt is a great way to store heat because it is cost effective, has an incredible heat capacity and conventional power systems are able to work with the temperatures it produces. Solar thermal plants avoid the difficulties photovoltaic power plants faces with electricity storage because solar thermal plants store the heat radiation that is generated from the sun. Although the United States is behind Spain and Germany in the photovoltaic power plant department, the United States has the three biggest solar thermal plant stations in the world: The Solar Energy Generating Systems in the Mojave Desert of California, the Martin Next Generation Solar Energy Center near Indiantown Florida, and Nevada Solar One, located in Las Vegas. All three of these solar thermal plants provide a rough total of 493 megawatts of clean renewable electricity. Although the United States is not a leader in renewable energy in the world this shows that we have the capability of doing so. In conclusion, if the high costs of solar power are not addressed, or if a viable storage solution for solar power can not be implemented, be it in the form of liquid batteries, hydrogen-oxygen fuel cells, or even storing solar power as heat with solar thermal plants, then we might not see solar power rising from the measly one percent of total power it provides in the United States. It will not matter if we can get photovoltaic technology up to even 50%, as long as we it is too costly for energy utilities to implement, or we do not have a way to efficiently store the solar power, generating clean renewable energy from the sun will only be a distant dream.