Solar power is seen as one of the renewable energy that would reduce the United States, overdependence on oil as a source of energy. The technology of harnessing energy has grown over the years, with the use of photovoltaic in generating electricity and solar thermal for heating water. The latest technology, which is still under development, is the use of CSP systems to generate electricity. The United States is advancing in the use of this technology, and currently it is the leading in the generation of power using CSP technology. This paper will discuss the history of solar power in the United States, the technologies used in the production of power using CSP, and the benefits of using this technology. The paper will also explore the barriers to large-scale production of CSP power and possible intervention, and discuss the future for CSP in the United States.
History of Solar Power in the United States
In 1970s, there was there was a first environmental regulation in the United States, but first, there was a Clean Air Act, that researched on air pollution and emission standards for automobiles. During this time, the Council on Environmental Quality was set up by the NEPA to carry out a national environmental impact assessment for projects funded by the federal government (Cohen 103). These developments led to the creation of limits to emissions from industrial plants, fuels and electric utilities. In 1074, there was an embargo that shook the US, which depended more on oil for energy; this made the United States to think of alternative ways of meeting its energy demands.
In 1977, the power behind CSP emerged with the development of the DoE, which was put in control of the federal energy agencies. More research was carried out by the DoE and other research groups on energy activities, which led to the development of policies and incentives for renewable energy resources such as CSP (Cohen 123). California led the nation in pushing for renewable energy resources, it used the DoE research and the attractive incentives provided by the PURPA to build SEGS; a 354 MW plant using a trough design was installed in Majove Desert (Cohen 147). This gave way to the construction of other CSP projects in California, and today, California has the first 80 MW plant, and this plant has remained the largest CSP in the United States.
The CSP Technology
CSP is a technique that is used for generating electricity using heat from the sun, this is a technology that is expanding quickly and is commercially viable. It requires a strong and direct solar radiation, which is used as a centralized source of power for many utilities, and produces more power in the late afternoon when the demand is high. The CSP technology uses mirrors to focus the sunlight on a heat transfer medium, the heat transfer medium is then heated to produce steam to power and engine or a generator that generates electricity (White 219). This technology has a potential of producing close to 300MW and supply approximately 100 megawatts; however, this value depends on the type CSP used. An effective CSP requires approximately 5.5 kWh/m2 of solar radiation per day; in California, the average solar radiation for an effective CSP ranges from 6.75-8.25 kWh/m2/ day, and its best performance is realized in flat and arid locations. The world’s best performance of CSP is realized in Australia, Sahara Desert and the U.S Southwest. The largest CSP in the United States was built in the 1980s and 1990s, in California desert, and today they are among the largest and most powerful solar generating systems around the globe. The United States has a number of plants, which have been operating since 1980s, and are located in the Southwest (Johnson 142). The United States is planning to install many more of CSP systems, and others are in construction states.
Types of CSP Systems
CSP has different technologies of power production, however, they all involve concentrating sunlight at a focal point located at a tube with a heat transfer material, the material is usually molten salt or synthetic oil. The synthetic material is usually pulled together and stored in a unit, and later used to produce steam to power conventional generators. All systems have arrays of mirrors for concentrating the sunlight.
Parabolic troughs are long, curved mirror pivoted to focus sunlight on tubes with a heat transfer medium, which is generally water or oil, and the steam produced after heating the heat transfer medium is directed o move a power generating turbine. The parabolic troughs are installed in a way that allows they to track the sun’s path, and this increases the amount of heat reaching the heat transfer material (Price 261). The parabolic trough CSP system is the most developed system, and it has been in use in the United States ever since. The maximum capacity size for this system ranges from 150MW to 250MW, the power within this range can power close to 44,000 homes; however, today, the largest parabolic trough CSP plant is 80 MW.
Solar Power Towers
In this technology, flat mirrors are used to focus sunlight on a central receiver containing a heat transfer fluid, which is often molten salt that can keep thermal energy for a long time. Solar power towers, unlike parabolic dishes, they concentrate heat energy at higher temperature, and this makes to have a higher efficiency when it is compared to parabolic dish CSP systems. This system had 10 MW facility, which operated between 1996 and 1999 in California, this system had a storage tank could store electricity for 3 hours after a sunshine (Price 124). In 2009, a 20MW power tower was put online in Spain; this is largest power tower demonstration plant.
In this system, mirrors are organized in a parabolic shape, which is like the shape of a satellite dish. The mirrors focus the heat on a central receiver that is mounted above the dish center. The receiver has a Stirling engine, which translates heat energy to mechanical power through cold fluid compression; the fluid can either be synthetic oil or water. The fluid is heated and allowed to expand through a turbine or a piston to produce mechanical power, which is converted to electricity using an alternator or a generator (Price 169). This system can be utilized to produce electricity in large scale by arranging many dishes in a large array. The newest system that uses this technology has 31.5% energy conversion efficiency, which is the highest efficiency of CSP technology plants. However, this system has a smaller production capacity, which ranges from 0.003 to 0.025 MW. Recently, this system has been approved in California for construction.
Linear Fresnel System
This system is among the new CSP technologies. This system resembles the parabolic trough system; however, it utilizes multiple flat mirrors arranged in rows to focus sunlight on a set of tubes, which increases the heat of the fluid inside the tubes. When this system is compared to the systems that use curved mirrors, it is less expensive; the flat mirrors are less expensive to manufacture. However, this system is less efficient when it is compared to other CSP systems.
CSP systems generates power during daytime, this is the time when electricity demand is high. The heat transfer process used in generation ensures a stability time of 15 to 30 minutes; this time is enough for the system to endure a passing cloud. The systems are affected by extended cloud cover and night, when the sun is not shining; therefore, they need thermal storage and supplemental fuels (White 284). Most of CSP systems are supplemented with natural gas for them to provide baseload power all the time. Most plants that use natural gas use steam engines in power generation and since the CSP also use steam engines in power generation; the two systems are easily hybridized. CSP systems can also be made to meet baseload demand using thermal storage technology; this storage can help the CSP system to operate for 70 percent of 365 days without fuel backups (Price 302). The thermal storage technology is a great improvement of the CSP system, which can only run for 15-30 percent of 365 days when it is generating without storage.
In 2008, the solar power produces only 0.09 percent of energy supplied in the United States; however, the production capacity is growing. Today, the United States have 429 MW installed CSP capacity, which makes it the leader in CSP generation, and the nation is still developing more generating plants, which totals to 7,000 MW. By 2020, the United States is sure of powering 2 million homes using CSP; this is from the projects that are under development.
CSP Projects under Development in the United States
California has 34 projects, which are planned to produce 9,183 MW; this is a potential capacity that includes 1600 MW to be produced from Stirling engine systems, 177 MW produced using Linear Fresnel System, 747 MW to be produced using power tower systems, and 8 projects with a potential of 4228 MW that are still in review process. The Mojave Desert has some CSP projects that are planned for construction; there is one project of 553 MW potentials that are still under construction since 2009. In 2007, there was a 25 year agreement between Pacific Gas and Electric and Solel to purchase power. In Florida, there is a hybrid of parabolic trough and gas systems with a potential capacity of 75 MW solar power. This power is projected to power Martin county and 11,000 homes will benefit from this project. Florida Power and Light and Lauren Engineers have an agreement of power purchase and this would benefit the nation.
Costs of CSP
The construction of a CSP plant takes approximately two years, it requires concrete, plastic, copper and steel. The cost of construction is about 80% of the plants total cost, this is higher when it is compared to a fossil fuel plant. However, unlike natural gas or coal power plants, CSP plants have zero fuel cost, the operational costs are 30 percent less when they are compared to those of gas and natural gas plants (U.S. Department of Energy 412). An installed CSP plant generates power for decades; in 1984, the first CSP plant was installed and this plant still generates power efficiently. These power plants might be expensive to construct but the benefits are huge and like the CSP plants, these benefits last for decades.
The Benefits of CSP
The United States’ average price of electricity generated from Coal and natural gas costs 6 and 9 cents/kWh respectively, and the cost of CSP electricity is 14-16 cents/ kWh. This shows that CSP is expensive when it is compared to Coal and natural gas, however, during peak demand, the CSP becomes more cost effective; this means that those who use the CSP generated power save a lot during this time, remember that the peak demand is during afternoon, and this is when generating using CSP is high (Sioshansi and Denholm 176). According to research, as the industry mature, the cost of building CSP system would come down, and the prices of power generated using these system would reduce to about 5 cents/ kWh.
The economic benefits of producing power using the CSP system might not be realized soon because the high cost of product of construction, however, if a nation continues to construct such plants, it would realize the benefits in a major way (Sioshansi and Denholm 179). For instance, the United States requires much power and its needs continues to increase as the population increases, as they are installing the CSP systems, their future costs of power generating are reducing because the nation will spend less of coal and natural gas power production (Kolb et al 197). The savings from the use of CSP would be used to fund other important developmental projects.
The development of CSP systems has created employment opportunities in the United States. The construction of the systems requires different expertise such as the engineers, geologists and the unskilled labor, and after it has been installed it requires the administration to facilitate its operations, therefore, the Americans with the skills in the respective field are employed in the CSP plant (Sioshansi and Denholm 181). This is bound to increase with the other projects that have been planned for construction in California as well as other parts of the country that have CSP potential.
Most of the CSP projects in the United States are constructed in areas that have less agricultural potential, and initially such areas such as Mojave Desert had little economic contribution to the nation, but now with the CSP projects, this region has a large economic contribution to the nation (Kolb et al 238). The energy produced from these projects has help residents around Mojave deserts and other citizen who use energy from this region to power their businesses; this has helped them extend their operation time, which has improved their earnings. The residents have also managed to put up businesses that use machines that depend on electricity for their operation. The companies producing CSP energy has managed to sign power purchase agreements such as the Florida Power and Light and Lauren Engineers, which help the company to sell its extra power and gain from the funds received.
The CSP projects produce energy with no harmful gas emissions, this is as opposed to natural and coal based projects which emit green houses gases. The United States which consumes much power, and has had many problems with complying with the Kyoto protocol, has managed to produce more energy adding extra green house emissions to the environment. The nation is investing more in CSP projects, and if the country continues to produce more of CPS, it will reduce its dependence on coal and gas producing plants, and thus reducing the CO2 and other green houses to the environment.
The construction of the projects does not require heavy digging of the ground, and this does not destruct the land, this is as opposed to coal and gas power production, which require heavy digging and installation of heavy machines that destructs the land.
The Barriers to large-Scale Deployment of CSP Production
The United States of America plans to produce power using CSP systems, but the projects are later converted to PV projects; recently, more than 2,500 MW that was planned for CSP projects was reconverted to PV projects (Kolb et al 292). This is because the CSP projects are costly to construct when they are compared to PV projects as well as the gas and coal power projects, and most countries such as the United States are shying away from deploying the CSP project for large-scale production. According to research, CSP projects can be made more efficient and produce more reliable power through dispatchability and storage, but this approach does not produce a more competitive power when it is compared to the oil-parabolic CSP hybrid systems (Johnson 216). Therefore, the nation is still afraid of investing in a technology that has high cost of construction, and the electricity produced is not competitive enough. The problem of high cost f electricity from CSP technology can be solved by investing in research to find better ways to come up with the technology to reduce the production costs using gas or coal to supplement CSP systems. More research on advanced CSP concepts such as molten salts and solar trough, direct steam and Fresnel, and molten salts and solar tower; this approaches have a potential of reducing the CSP cost of power production (Johnson 231). If a more efficient technology is used and the cost of producing electricity lowered it will result in the development of the CSP technology
The future prospects of CSP in the United States
The United States has a potential of CSP production with the planned CSP projects and more in places that has a potential, and with the ongoing research to reduce the cost of energy produced using CSP systems, as well as its efficiency, CSP is expected to be a key player in the nation’s future. Solar energy is the biggest resource not only in America, but around the globe and if efforts are not made to commercialize it, then regions with the potential might not realize its importance (Johnson 163). The cost of construction of CSP system is very high; therefore, many private investors shy away from investing in such projects. The government of the United States should find a way to cut the construction costs to easy the investors’ investment costs (Hamilton 215). This can be done by giving incentives to those wishing to invest in CSP production; building infrastructure in areas of potential solar power production and reducing or eliminating import duties on CSP construction materials. This would help the CSP industries to produce power that is competitive in the market by offering lower prices. The government should also come up with a tariff that will increase the consumption of power produced, for instance, for those who consume CSP power during the time when the CSP plants are generating more power are charged less; this will increase the market for CSP (Hamilton 217). The increase in market will attract many investors to invest in CSP, and more regions with energy solar resources will be exploited giving the nation more clean and cheap energy. The United States should also invest more in research on efficient ways of CSP production and solar energy exploration; this will ensure that the solar resource is fully exploited in the United States. The future for solar energy in the United States is promising, but any further achievements will depend on the government’s efforts to make it exploit and commercialize the resource.
CSP technology is a technology that utilizes a free energy resource, which is the sun, this technology has been proved to be viable in United States; there are several projects that are already generating and supplying energy. There are several projects, which are still under construction, others planned for construction, and there are some areas that are still unexploited; this shows its future potential in the United States. However, the low efficiency and cost of constructing the plants hinders its exploitation and production in large-scale. The hindrances can only be eliminated by doing more research on efficient and less costly techniques for CSP production. This technology should not be quickly assumed because of it costs, however, the government of the United States should provide incentives to investors in this industry to encourage them to exploit the CSP.