When doing the research for a article on new green products, I was unaware of many of the different ways to convert the energy of the sun into electrical power. I have written about solar cell or photovoltaic cell systems, so let’s look at another type of solar energy system.
The Stirling engine goes back to the early 1800′s, when steam was the order of the day. Steam was used to power factories, trains, and many types of work that required lots of horsepower. However, with steam came the danger of a boiler blowing up when something went wrong. Robert Stirling saw a different approach. His invention still used fire to heat the hot chamber but instead of steam, he used the heat to move pistons.
Sense its incarnation there have been many variations of the Stirling engine and many patents. The engine’s simple design demands tinkering – everyone wants to add or change something to make it better. The engine has very few moving parts, requires only a single external heat source, is very efficient, and is quiet. With the new space age materials available, the problem of piston overheating is no longer a problem like it once was.
The heat source needed to start and maintain the Stirling cycle depends on the temperature difference between the hot and cold chambers. The greater the differential between chambers, the faster the engine will operate. In some cases the difference that occurs when the cold chamber is cooled by wetting it is enough differential to start the engine.
The Stirling cycle is pretty simple. When a heat source is applied to the large end, it causes the air to expand which moves a piston. A flywheel is used to maintain movement between cycles and add a convenient place to tap the power from the engine. What is so amazing about this design is that the design is very scalable. Engines have been produced that are as small as your hand to a large as a car but the concepts remain the same.
The reason the Stirling engine works so well for a solar application is that heat from the sun can easily be concentrated to heat the hot chamber. A parabolic mirror much like that seen with the roof mounted satellite dishes is used to gather and focus the sunlight. With the sunlight focused onto the hot chamber of the engine, the temperature raises and the engine starts running. Connect the output shaft to a generator, and electricity is the product.
The engine and support equipment is contained in a package small enough to be suspended from the end of a metal arm, much like the design of satellite TV systems but on a much larger scale. Some systems are producing 25K watts of power and have been installed and operational for a couple of years.
I will compare the different solar technologies in a later article. For now, I need to lay a foundational understanding of each of the green products used to produce power so a comparison can be made.
Michael
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- Renewable Energy From An Old Concept
- Using The Sun’s Energy In A New Way
- Green Products Has Located an Incredible New Low-cost Solar Design
- Green Products Has Located an Incredible Low Cost High Output Solar Design
- Energy-Efficient Homes by Emmy Homes
