This solar collector in Spain uses a point focus parabolic mirror and has a Stirling engine at the center.
Wikimedia Commons
Promising new solar technology to generate electricity is almost a cliche these days. Let’s look at some promising old technology. Today, on Engineering Works! Listen to the podcast.
When people talk about solar energy, they usually mean one of two things. Photovoltaic panels or solar concentrating plants. Some engineers are trying something else. An updated version of a two-hundred-year-old invention to turn sunlight into electricity. This old technology is something called a Stirling engine. A Scottish clergyman named, you guessed it, Stirling, invented it in 1816.
The idea is simple. A Stirling engine has two cylinders and pistons. Kind of like a two-cylinder motorcycle engine. The space above the pistons is filled with a fluid, usually air or helium. Heat the gas in one cylinder and it expands, moving the piston. The gas cools and moves to the other cylinder, where it moves that piston and flows back to the first cylinder, where it’s heated again and the whole cycle starts over. It’s more complicated than this, but you should get the idea. They’re a lot more efficient than conventional internal combustion engines and need only a little outside heat to keep the cycle going.
In solar power plants, sunlight provides the heat that makes the gas expand. Sunlight is focused on the Stirling engine by a concentrator that looks like a big, shiny satellite TV dish. Stirling engines spin electric generators the same way turbines or diesel engines do.
Whew! It’s getting hot in here. We’ll see you next time.
Engineering Works! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station.
Tags: Electricity, Engineering, Engines, Internal Combustion, Solar Power
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