Q: Why would anyone go to the trouble of building this contraption when they can just go out and buy a bunch of solar panels?
A: Short answer: because I can. I love to make things. Someday, when my electric meter is spinning backward, I'll not only enjoy the financial rewards but will also be proud that I built the system.
Long answer: When most people think solar power, they think of the panels people put on their roof. Those panels convert light into energy, which is great, but light is only one component of the energy we get from the sun. As we in Tucson know, sunlight produces an enormous amount of heat, which goes largely untapped. Currently, the only way we use solar heat is to warm our swimming pools or provide hot water. I want to do much more. I want to be completely energy independent in the next couple of years and doing that with just the current off-the-shelf technology is not only cost prohibitive, but inefficient.
Q: What is a Tesla Turbine?
A: A Tesla Turbine is a bladeless rotary engine that uses flat plates closely stacked in such a way that when a gas or liquid is forced across them at an angle, they are forced to spin in the direction of the flow of the gas or liquid due the principle of “boundary layer effect.”
Q: What is a “boundary layer” and how does it make the turbine move?
A: When a stream of gas or liquid flows over a solid surface, the boundary layer is a very thin layer of the stream that wants to stick to the surface rather than flow along with the rest of the stream. Think of it as spraying water onto a mirror. Most of the water flows off but there will always be droplets left behind. The plates in a Tesla Turbine are so close together (about the thickness of 5–10 sheets of paper) that there is only room for the boundary layer as it flows between the plates. The stream “drags” the plates in the direction of the flow and spins the plates.
Q: Will you use steam to power the turbine?
A: I certainly could but I’ll probably use what’s called an “Organic Rankine Cycle.” It is similar to a steam system in that I’ll be boiling a liquid to form a gas that will spin the turbine. But instead of water it will use a liquid closer to the one in your air conditioner. While this system is a bit more complex than a steam system, the fluid boils at much lower temperatures than water, which should be more efficient.
Q: How much energy will your Tesla Turbine produce?
A: The honest answer is, I'm not sure. There are a lot of unknown factors involved that effect the final total. It will depend on how big my solar collector is. How efficient the Organic Rankine Cycle is. How many hours a day the turbine can run. Any number I quote now would be more of a guess than an answer.
UPDATE! The folks over at Phoenix Navigation told me that in their experiments they've gotten instantaneous output readings of 45-49 volts at 18 amps. That's 810 watts. Ideally, we would be able to collect and store enough heat to run the turbine 24 hours a day. However, initially we'll probably only be able to run while the sun is shining. So if we put out 810 watts for 8 hours a day for 30 days, we would make 194 kilowatt hours of electricity. If we ran for 24 hours a day we would create 584 kilowatt hours of electricity. We average about 1500 kilowatt hours a month so we would be creating between 15-39% of our current power needs.
Q: Is this a new idea?
A: Not at all. Nikola Tesla invented the Tesla Turbine in 1913. People have been using solar heat to generate electricity for years; a number of very large power plants use solar heat to create steam using molten sodium. The problem is that the technology hasn't been scaled down to a size that is feasible for our homes. That is what this project is about.