1、1 附 二 Tower of Power By Gonzalo Garca-Sobrinos, Ignasi Salvador-Vill, ICCP, and Jess Serradilla-Echarri The past few decades have witnessed growing interest in such renewable sources of energy as the sun, the wind, hydrogen cells, biofuels, rivers, tides, and the earths internal heat. Because of the
2、ir relative novelty, the various technologies continue to undergo rapid improvement, generating new engineering challenges. A recently completed solar power project near Sevilla (Seville), Spain, illustrates this point. Known as PS-10, the project consists of several hundred large movable mirrors, k
3、nown as heliostats, that reflect direct solar radiation to a central receiver located near the top of a 115 m high concrete tower. Components within the receiver convert the solar radiation into electricity. Because the tower is unique in many ways, its design proved challenging. In particular, the
4、tall structure had to be sufficiently robust to support large loads yet maintain an aesthetically pleasing appearance that would be compatible with the surrounding environment. With regard to the potential development of solar energy, Spain is one of the most attractive countries, as it enjoys the g
5、reatest amount of sunshine of any European country. In fact, the Plataforma Solar de Almera is Europes largest center for research, development, and testing of technologies used to concentrate solar energy. Located in Almera, Spain, the facility is part of the Centro de Investigaciones Enrgeticas, M
6、edioambientales y Technolgicas. Moreover, Spain is the worlds fourth largest manufacturer of solar power technology. Several hundred movable mirrors, known as heliostats, below, reflect the suns rays into the 115 A 115 m high tower is the crowning achievement of PS-10, Europes first commercial gener
7、ating facility to be powered by the sun. Constructed in Spain, the tower has been designed to support large loads, facilitate public access, and complement its surroundings as much as possible. Photograph: Getty Images 2 m tall tower, which, as the previous pages suggest, appears to learn toward the
8、 field of reflectors. Getty Images Given these factors, the Spanish government is committed to producing 12 percent of its primary energy that is, the total amount of energy supplied by the nations power grid from renewable sources by 2010. This plan includes an installed solar generating capacity o
9、f 400 Mw. In March 2004 it removed economic barriers that prevented the connection of renewable energy sources to the power grid, making it easier and safer for investors to develop new projects in this field. Facilities of the PS-10 type employ a field of heliostats with a control system to reflect
10、 direct solar radiation to a central receiver located on a mast or post. The concentrated solar radiation heats up a fluid located in the receiver to temperatures between 500C and 1,000C. This thermal energy can then be used to generate electricity. In fact, PS-10 is Europes first commercial generat
11、ing facility to be powered by the sun, having begun operations earlier this year in southern Spain in Sanlcar la Mayor, near Sevilla. It is the first of a set of solar power plants to be structed in the same area that will have a total generating capacity of more than 300 MW by 2013. Power will be g
12、enerated using a variety of technologies. PS-10 produces electricity with 624 heliostats, each having an area of 120 m2. All told, the power plant occupies 60 ha of land. Directed by a central computerized system, the heliostats concentrate the suns rays at the top of the tower, where a solar receiv
13、er and a steam turbine are located. The turbine drives a generator, producing electricity. With a nominal capacity of 11 MW, the plant produces 24.2 GWh of electricity annually. Construction of the plant cost 35 million (U.S.$47.8 million). of that amount, 5 million (U.S.$6.8 million) came from the
14、European Unions Fifth Framework Programme, a fund that supports research and development work on innovative technologies. Although power produced 3 by PS-10 is three times more expensive than that from conventional sources, the cost in similar plants is expected to fall as the technologies develop.
15、The PS-10 plant is owned by Solcar Energa, S.A. The firm, commonly referred to as Solcar, designs, promotes, finances, constructs, and operates power plants that use the sun as their primary energy source. Solcar is a subsidiary of Abengoa, of Sevilla, a technology company whose various business uni
16、ts concern themselves with solar energy, bioenergy, environmental services, information technology, and industrial engineering and construction. Solcar subcontracted the construction of the PS-10 plant to Abener Energa, S.A., a firm that is one of Abengoas subsidiaries and focuses on construction. I
17、n turn, Abener subcontracted the design and construction of the solar tower to Alternativas Actuales de Construccin S.L. (ALTAC), of Madrid, Spain. ALTAC specializes in designing and constructing industrial chimneys and tall concrete structures. At the beginning of the project, the tower design was
18、not established. Therefore, it was necessary to assess all requirements to define a suitable, feasible, and attractive solution. For example, the tower had to support various types of large, heavy equipment: The solar receiver comprises four interchanger panels that are 5 m wide and 12 m high. Cover
19、ing an arc of 180 degrees and located on the tower at an elevation of 100 m, the receiver has a total weight of 240.5 metric tons. A 15 m long steam drum is used to collect the steam, which drives the turbine. with a total weight of 74.5 metric tons, the drum is situated atop the tower 113.5 m above
20、ground. Four pumps below the receiver are needed to pump up water. weighing a total of 12.5 metric tons, the pumps are located at an elevation of 85.8 m. A 5 m long reheater with a total weight of 6.4 metric tons is located 34.1 m aboveground. A 3 m long degasifier weighing 3.6 metric tons is locate
21、d at the same elevation as the reheater. Ductwork and pipes for water and steam, distributed among several platforms, have a total weight of 176 metric tons when full. ALTAC Beginning at an elevation of 100 m, an opening extends 14.1 m in width and 15.3 m in height to enable the suns reflected rays to reach the receiver.
