Abengoa Solar has been selected by Xcel Energy, Colorado’s largest electric utility company, to build a demonstration parabolic trough concentrating solar power (CSP) plant at its Cameo coal plant.
The project is the first to integrate an industrial solar installation into a conventional electrical power plant. Construction is expected to start within a month and the plant is expected to be operational by the end of the year. The project, awarded to Abengoa Solar by Xcel, is the first project under an Innovative Clean Technology program that has been approved for Xcel Energy by the Colorado Public Utilities Commission.
The goal of the project is to prove that the heat produced by a solar facility can increase the efficiency of a conventional power plant while also lowering carbon dioxide (CO2) emissions. Successful integration of this technology may enable future large-scale applications of this technology into other power plants.
"We continue to move forward in developing ways to help us reduce our impact on the environment," said David Wilks, President of Energy Supply for Xcel Energy. "If this demonstration works, we may be able to implement this type of technological advance in other coal-fired power plants to help further reduce carbon dioxide emissions in Colorado and possibly other areas of our service territory."
This four thermal megawatt solar installation will use state-of-the-art parabolic trough collectors developed by Abengoa Solar.
Ken May, Director of Abengoa Solar IST, emphasized the high potential of large-scale applications of the industrial solar installation technology: “Proper use of the solar thermal energy produced at these facilities can improve plant efficiency while lowering CO2 emissions. The successful integration of solar and coal technologies will encourage more widespread use throughout the utility sector.”
Parabolic Trough Technology for Industrial Solar Installations
Parabolic trough technology can be used for both electricity generation as well as for producing thermal energy for industrial processes. More extensive use of this technology could have a significant positive impact on the environment.
Abengoa Solar’s industrial parabolic trough technology installation utilizes collectors that track the sun during the daytime in order to concentrate solar radiation onto a heat-absorbing pipe located at the focal line of the parabola. The heated fluid that circulates through the pipe reaches high temperatures and, by means of a heat exchanger, produces energy that can be used to generate steam, to heat water or air, or to run an absorption machine for an air conditioning system.
Concentrating Solar Power Parabolic Trough
Trough technology is a clean and mature solar power solution with years of successful power generation behind it. Troughs have been in use since the 80s with outstanding results. The technology has been improving steadily for the last 30 years, and modern troughs operate more efficiently at lower cost. Today, there is more than 300 MW of CSP trough power in operation around the world, with 400 MW under construction and around 6 GW in development.
Introduction to Technology
A parabolic trough is a large, curved mirror that sits on a motorized base, allowing it to follow the movement of the sun throughout the day. The mirror’s unique parabolic shape is designed to gather a great deal of sunlight and then reflect that light onto a single point, concentrating the solar power.
A receiver tube sits at the point where the mirror concentrates all the sunlight. The tube is filled with a synthetic heat transfer oil, heated by the mirror’s light to around 750 F (400 C). This superheated oil is then pumped from the solar field to a nearby power block, where the oil’s heat is converted to high-pressure steam in a series of heat exchangers. This steam pushes a conventional steam turbine, creating electricity.
Parabolic trough technology is the most developed CSP technology, and has been a major focus of Abengoa Solar’s research efforts. Abengoa Solar is currently deploying parabolic troughs at the Solúcar Platform outside of Seville, Spain a collection of five 50 MW plants. Continue on
The main components of parabolic trough technology are:
* The parabolic trough reflector: The cylindrical parabolic reflector reflects incident sunlight from its surface onto the receiver at the focal point. Typically, the reflector is made of thick glass silver mirrors formed into the shape of a parabola. Alternatively, mirrors can be made from thin glass, plastic films or polished metals.
* The receiver tube or heat collection element: The receiver tube consists of a metal absorber surrounded by a glass envelope. The absorber is coated with a selective coating to maximize energy collection and to minimize heat loss. The glass envelope is used to insulate the absorber from heat loss, and is typically coated with an anti-reflective surface to increase the transmittance of light through the glass to the absorber. For high temperature CSP applications, the space between the absorber and glass tube is evacuated to form a vacuum.
* The suntracking system: An electronic control system and associated mechanical drive system is used to focus the reflector onto the sun.
* The support structure: Typically made of metal, the collector support structure holds the mirrors in accurate alignment while resisting the effects of the wind.
Solnova 1, 3 and 4, with 50 MW each, are the first three parabolic trough technology-based plants of a total of 5. At Abengoa Solar, we believe in this technology, and for this reason have research groups focused on parabolic trough technology.
The Most Mature CSP Technology
The first commercial CSP plants were parabolic trough collector systems installed in the United Sates in the 1980’s. Continued research since that time has improved the technology making it more reliable and efficient. Troughs remain the most developed and commercially-ready CSP technology.
Regarding Trough. technology, there are several variables to be analyzed when defining an installation. The most important requirements for a C.S.P. plant are:
* Topography: the site needs to be level, preferably with a slope less than 1%
* Irradiation: the direct normal insolation (DNI) should be a high as possible
* Water Availability: water is needed for cooling in the power block
* Electric Transmission: electric lines and transmission capacity are needed to convey solar power from the plant to the consumer
Land Requirements for 100 MW Plants
Individual parabolic trough collector modules are attached together to form a “collector” that can be from 100 to 150 m long. Collectors are configured together to form a collector row. Parabolic trough plants are made up of many parallel collector rows covering large rectangular areas of land. The table below shows the approximate surface of land needed for plant construction. Besides the surface specifications (acres), the approximate width (x in m) and length (y in m) of an intended rectangular plot have been included.
Abengoa Solar focuses on developing and applying innovative solutions to generate power and energy from the sun. Abengoa Solar’s headquarters in Lakewood, Colorado, comprises 50,000 square feet of office and manufacturing space where more than 70 people are employed in engineering, research and development, manufacturing, project development and support functions. In addition, Abengoa Solar has in the US offices in Arizona and California.
Abengoa is a technology company that applies innovative solutions for sustainability in the infrastructure, environmental and energy sectors. The company is listed on the Spanish Stock Exchange and is present in more than seventy countries, in which it operates through its five business units: Solar, Bioenergy, Environmental Services, Information Technologies, and Industrial Engineering and Construction.