作为一种储存和释放太阳能的新方法,美国内华达州和意大利西西里岛都将在太阳能热发电厂使用熔盐法。
此前,已有人使用过太阳能热电厂熔盐———2009年11月西班牙在Alcazar de San Juan建立了熔盐工厂。此外,在今年5月,美国能源部位13家公司拨款6200万美元用于热太阳能技术发展,而且其中一些正考虑使用熔盐。
SolarReserve是一家总部位于洛杉矶的太阳热能公司,该公司开发的技术使熔盐系统成为可能。两个不同工厂都将使用巨大的定日镜,将阳光反射到内装钾、钠也硝酸盐熔盐液体的上水管上,液体盐吸收阳光热量变成高压蒸汽推动涡轮并产生电力。
熔盐吸收的热量能在无阳光条件系保持24小时,这让该技术超然出众,这意味着工厂可以延长运营时间增加热量。一旦熔盐冷却,再回到它的位置将被再次加热,用蒸汽重新启动一遍该系统的所有进程。
内华达州的Crescent Dune项目将建成一个100兆瓦的电厂,预计将产生每年产生48万兆瓦小时电力。周四,美国国务院得到了内华达州公用事业委员会批准。此外,SolarReserve的子公司,Tonopah Solar Energy与Nevada Energy签署了长达25年的店里购买协议。
该工厂预计将造就450个建造业职位,45个机组运行及4000长期的服务岗位。
另一方面,名为Archimedes的西西里岛太阳能热电厂已在两个星期前由欧洲能源公司Enel拉开帷幕。
熔盐法工作流程图
As a new way to store and release solar energy, U.S. state Nevada and Sicily, Italy will both use molten salt to operate solar thermal plants.
The use of molten salt in solar thermal plants has been done before – Alcazar de San Juan, Spain obtained a molten salt plant in November 2009. Also, in May of this year, the U.S. Department of Energy gave 13 companies $62 million for the development of thermal solar technology, and a few of them are considering the use of molten salt.
SolarReserve, a Los Angeles-based solar thermal company, developed the technology to make this system possible. Large heliostats will be used in the two separate plants in order to reflect sunlight onto pipes that carry a molten salt liquid, which has potassium and sodium nitrates in it. The liquid salt then absorbs the heat from the sunlight in order to make high-pressure steam, which powers the turbine and produces electricity.
What makes this technology useful above and beyond other solar thermal plants is that the molten salt holds the heat it absorbs up to 24 sunless hours, which means the plant can use it's heat for an extended amount of time increasing operation hours. Once the molten salt has cooled, it recycled back into the system where it will be reheated and used once again to create steam, restarting the process all over again.
Nevada's plant, the Crescent Dunes Solar Energy Project, will be a 100-megawatt plant and is expected to generate 480,000 megawatt hours of electricity annually. The U.S. state received approval for this project by the Public Utilities Commission of Nevada on Thursday. In addition, SolarReserve's subsidiary, Tonopah Solar Energy, signed a power of purchase agreement with Nevada Energy that will last 25 years and will provide energy from the plant.
The plant is expected to create 450 construction jobs, 45 permanent jobs for plant operation and 4,000 indirect jobs for local service providers and suppliers.
On the other hand, Sicily's solar thermal plant, named Archimedes, has already opened two weeks ago by the European energy company Enel.