Concentrating Solar Power

Unlike photovoltaic solar panels that directly generate electricity, concentrating solar power (CSP) generators use it in an indirect manner by collecting solar energy by the use of mirrors or lenses. Think back to when you were a kid. Did you ever take a magnifying glass and focus the sun’s light onto a piece of paper or even an insect? Do you remember how the object got extremely hot? This is the same principle behind concentrating solar power generators. Concentrated solar power systems are divided into three divisions; concentrated solar thermal (CST), concentrated photovoltaics (CPV), and concentrating photovoltaics and thermal (CPT).

There’s a wide range of concentrating solar power technology that exists today. Each concentration method is capable of producing high temperatures and high thermodynamic efficiencies, but they vary in the way they track the Sun and focus light. They include:

• The parabolic trough
• The concentrating linear fresnel reflector
• The Stirling dish
• The solar power tower

The parabolic trough consists of a linear parabolic reflector that focuses light onto a receiver positioned along the reflector’s focal line. The receiver is a tube filled with a working fluid. The reflector follows the Sun during the day by tracking along a single axis. These devices are perfect for land-use technologies. Concentrating linear fresnel reflectors are CSP-plants that use tiny mirror strips instead of parabolic mirrors to focus the sunlight onto tubes with working fluid. These mirrors are flat and cheaper than parabolic mirrors, plus they are smaller, which means there is room for more mirrors and ultimately more solar power. The Stirling solar dish is an engine system that consists of a stand-alone parabolic reflector that focuses sunlight onto a receiver positioned at the reflector’s focal point. Unlike with a parabolic trough, this device tracks the Sun on two axles. Power towers are still the most cost-effective of this group. They offer a higher efficiency and better energy storage capability among concentrating solar power technologies. The Solar Two in Barstow, California is a great example of a concentrating solar power system.

How Concentrating Solar Power Systems Work

If you understand the concept of the magnifying glass above, you should be able to understand how concentrating solar power systems work. Basically, the mirrors or lenses are used to ‘concentrate’ the large amount of solar energy (sunlight) onto a smaller beam. That beam of energy is then used to heat up water which turns into steam. The steam is then used to drive a steam turbine or a power plant that creates electricity.

Cost of Concentrating Solar Power Generators

In 2009, the cost of building a concentrating solar power station was ranged from $2.50 to $4.00 per watt. However, it’s important to remember that the cost of building a power station is minimal compared to the savings in fuel. The sun’s heat and energy is free. At that price, a 250MW CSP station would cost over $600 million dollars to build, equaling 12-18 cents per kilowatt-hour. Still, with the continuous efforts to advance technology in solar power, experts believe this number will decrease up to 30% over the next few years. This decrease will allow more and more people to take part in using solar power to power their homes during and not during power outages.