Micro cogeneration?

Student 07 · 12-16-11, 01:30 PM

Hi,
I was looking at micro cogenerators like Freewatt and they seem like a good idea. Why not get electricicty and heat from your fuel. It seems like it would work great when you're off the grid. And even on the grid, you're paying for fuel to produce heat, why not get electricity as a byproduct? I am sure it could be used, or like solar and wind power, be sold back to the utility.

What is holding me back is that they are very expensive, I have been told that a small microcogenerator costs around $50,000. The return on investment doesn't pencil out. You still have fuel costs. It seems like a technology that is ripe for a hack.

I don't understand why they are so expensive.

Couldn't a guy just use a liquid cooled motor to run a generator, and instead of a liquid to air (radiator) heat exchanger (which blows heat outside) use a liquid to liquid heat echanger to preheat water for the house? The preheated water could be used for DHW or radiant floor heat. The alternative (which almost everybody is doing now) would be to use fuel to create heat and pay for the electricity seperately. The fuel for the motor would supply both electricity and heat.

I am thinking that a 250cc motorcycle engine would have plenty of power to run a 10kwh generator. The motor would be geared to operate at 1500rpm so it shouldn't take a lot of fuel. If the heat from the motor is kept at 190*, it shouldn't take long for it to heat a hot water tank.

I am hoping that somebody with experience or a better understanding than me can explain the pro's and con's of this kind of system. Thanks in advance for your responses.
Jeff

12-16-11, 01:30 PM	#1
Student 07 Helper EcoRenovator Join Date: Dec 2011 Location: Gresham OR Posts: 35 Thanks: 0 Thanked 3 Times in 3 Posts	Micro cogeneration? Hi, I was looking at micro cogenerators like Freewatt and they seem like a good idea. Why not get electricicty and heat from your fuel. It seems like it would work great when you're off the grid. And even on the grid, you're paying for fuel to produce heat, why not get electricity as a byproduct? I am sure it could be used, or like solar and wind power, be sold back to the utility. What is holding me back is that they are very expensive, I have been told that a small microcogenerator costs around $50,000. The return on investment doesn't pencil out. You still have fuel costs. It seems like a technology that is ripe for a hack. I don't understand why they are so expensive. Couldn't a guy just use a liquid cooled motor to run a generator, and instead of a liquid to air (radiator) heat exchanger (which blows heat outside) use a liquid to liquid heat echanger to preheat water for the house? The preheated water could be used for DHW or radiant floor heat. The alternative (which almost everybody is doing now) would be to use fuel to create heat and pay for the electricity seperately. The fuel for the motor would supply both electricity and heat. I am thinking that a 250cc motorcycle engine would have plenty of power to run a 10kwh generator. The motor would be geared to operate at 1500rpm so it shouldn't take a lot of fuel. If the heat from the motor is kept at 190*, it shouldn't take long for it to heat a hot water tank. I am hoping that somebody with experience or a better understanding than me can explain the pro's and con's of this kind of system. Thanks in advance for your responses. Jeff