Solar and Wind Power

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.

The Stirling engine has many different designs, some more efficient than others. Some designs use the two cylinder Alpha design, some the Beta single cylinder design and some the Gamma design (a variation of the beta for use in multiple cylinder applications). The beta Sterling design has a single chamber with two pistons and uses a highly efficient regenerator gas as the thermal conductor.

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!

The basic operation of this thermal engine is really quite simple. The engine has two chambers, one hot and one cold. When an external heat source is applied the hot air expands moving a piston and flows to the cold chamber. A flywheel is attached to maintain movement.

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 better-designed engines and new types of material, a movable (tracking) parabolic mirror, and a single Stirling engine you can produce 25 kilowatts of electricity.

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