Solar Trough: Concentrated Solar Radiation

The solar trough system, also called the line-focus collector, focuses sunlight to create electricity. The solar trough system has its name because each collector is shaped like a trough that is parabolic (curved) in shape. There is a tube running down the middle of the trough with fluid inside. Mirrors inside the trough concentrate sunlight on that tube and heat the fluid inside it. The fluid is usually dark oil, but other substances can be used. The oil can get as hot as 752F (400C). The heat from the oil is transferred to water, which turns into steam. The steam can be used to power a turbine-generator or other machinery to produce the electricity.

Solar rough systems are modular.That means they can be linked together to make a larger amount of electricity than can be created by an individual trough. Many troughs together form a collector field when they are put in parallel rows. In a collector field the troughs are aligned in an axis running from north to south allowing the troughs to track the sun from east to west.

There are several ways to make sure trough systems produce electricity after the sun goes down. Some trough systems have a means of thermal storage. That is, they can save the heat transfer fluid while still hot. By doing so, the troughs can still power the turbines after the sun goes down.

However, trough systems are usually hybridized, meaning they are combined with a fossil fuel system for supplying electricity.Usually, the heat is created by natural gas. Using a gas-powered steam boiler is also possible. If trough systems are hybridized, they can produce power at all times. Coal-powered plants can also be supplemented by the trough system.

Solar trough systems have many benefits, which is why they have been so widely adopted. Except for the generator, trough systems require minimal maintenance. The energy they produce is not quite on the price level of fossil fuel-produced electricity, but the figure is often very close. As with all solar energy technologies, the fact that the sun does not shine at all times is a major drawback so for soloar trough systems to operate to capacity, they need intense, direct sunshine. Solar trough systems also take up a significant amount of space when they are linked together to provide power on a widespread scale.

Solar Trough: Concentrated Solar Radiation copyright 2011

photograph of the Odeillo Solar Furnace