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.

This system is not new; it was originally conceived in 1816 as an industrial rival to the steam engine. It has been largely underutilized for the past century. With the need for renewable energy sources caused by the overuse of the fossil fuels interest has resurged in solar designs, and it is now being designed into many new solar collector systems.

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.

To operate the Stirling engine only an external heat source is required, which could be anything from solar heat to the heat produced by decaying plants. In one model, the heat from a human hand powers a small version of the Stirling engine!

Operation is simple: the gases are heated by an external source, causing the hot gas to move toward a cold chamber, in the process, a piston is driven and a flywheel rotated. To put it simply, movement is achieved from heat expansion. A few knock-offs of the Stirling engines are small enough to fit in your hand. Others system are designed to drive electrical generators. They are a about the size of a fifty-gallon drum.

The Stirling engine is ideal for use in a solar power generating system. With one of the hottest heat sources available (sunlight), the hot chamber will continue to operate without external fuels as long as there is daylight. This makes it ideal for use as a peaker type power plant when the demands for electricity are at there highest.

With the space age list of available materials, the pistons in the hot chamber are much better designed to handle the high temperatures that would have fried previous generations. The new systems with the right mirror design and decent tracking systems are averaging up to 25 kilowatts of electricity

In a future article about green products I will list the different solar technologies and how they compare to the competition.

Michael