About me and why I created this physics website.
A Stirling engine generator is simply an electrical generator powered by a Stirling engine. This is a device that gets searched for a lot on the internet, but there is a real lack of good information about these devices. So that's why I created this page. It turns out that there are a number of companies that sell Stirling engine generators, and I'm going to list these companies below, along with some information describing their function.
I wanted to list only those Stirling engine generators that are practical in terms of the heat source they use. For example, a Stirling engine that can use the heat created from burning "something" that is widely available, such as wood or gas, is practical. But a Stirling engine that can only run on concentrated solar energy is not as practical, since you can't always produce power when you need it, not unless the sun is shining.
The engines below are listed in order of smallest to largest power rating.
1. Microgen Engine Corporation
• Power level: 1 kW (one engine)
• Engine type: Free-piston
• Working gas: Helium
• Heat source: Burning of gas or wood pellets
• Company website
2. Combined Energy Technology
• Power level: 1 kW (two different engines)
• Engine type: Beta
• Working gas: Nitrogen (?)
• Heat source: Burning of wood chips and wood pellets (in one engine), or burning natural gas and propane (in another engine)
• Company website: http://stirling-tech.com/ (Clickable link not provided because it does not have the more secure "https" protocol. But it's okay to go to their website anyway.)
3. Qnergy
• Power level: 1.4 kW and 5.65 kW (two different engines)
• Engine type: Free-piston
• Working gas: Helium
• Heat source: Burning of wood, natural gas, propane, or any gaseous fuel
• Company website
4. Cool Energy
• Power level: 3 kW and 25 kW (two different engines)
• Engine type: Gamma
• Working gas: Nitrogen
• Heat source: Any, such as solar or industrial waste heat
• Company website
• Additional info: This is a low temperature Stirling engine capable of running with a hot source temperature of 150 to 400 degrees Celsius. The engine and generator are contained inside a large pressure vessel. This is because the "shape" of the engine means that it cannot withstand high internal pressure. So to deal with this, the engine, and generator, must be housed inside a large pressure vessel that is pressurized to the mean internal engine pressure.
5. ADI Thermal Power
• Power level: 25 kW (one engine)
• Engine type: Beta
• Working gas: Helium
• Heat source: Burning of almost any fuel, including propane, ethyl alcohol, natural gas, biomass, solar heat, and fuel cells
• Company website: http://www.adisolarthermal.com/stirling/ (Clickable link not provided because it does not have the more secure "https" protocol. But it's okay to go to their website anyway.)
Here are some useful questions to ask these companies when contacting them about their Stirling engine generator units:
• What is the cost of the unit, and what is the typical payback period (assuming this is something that will save money – such as from reducing fuel cost, or make money – such as from the production of electricity using waste heat)?
• What is the size and weight of the unit?
• What are the maintenance requirements, and what are those costs?
• Who else has purchased this unit whom you can contact to find out more about it?
• How often does the engine need to be re-pressurized to compensate for leakage of working gas?
• Are there peer reviewed studies, and/or studies done by colleges/universities, that analyze the performance of the engine?
• What is the thermal efficiency of the unit; that is, what percentage of the heat energy input is converted into electrical energy?
• Can the engine run on different working gases? For example, can an engine that runs on nitrogen also run on helium? An engine running on helium produces more power than running on nitrogen, but there may be practical considerations that advise against doing this.