Where Do I Find Low RPM / High-Output Generators?

Start with how you are planning to power the generator. What is going to be your "prime mover"? Gas, oil, diesel, wind, water, squirrels?

i am sorry , iforgot to say iwould like to run the generator with a combination of wind and solar , if possible.

You will likely need a lot of wind and a very large generator to power and electric water heater. There are formulae available to get a rough estimate of the turbine blade size you would need for a given size of service, but the one I use for quick discussions says the following:

To run a typical water heater for a family of 4, you need 3800 watts but with on/off-time, it comes out to about 500kWh/month, 6000kWh/year. With a 12MPH average consistent wind speed, that will make your wind turbine at least 15 feet in diameter. Any less wind or smaller turbine will result in insufficient power.

Wind turbine diameter calculator

Solar is much more complicated, but if you go to the home page of that website they have a treasure trove of links to very helpful sites. But one thing they will all say is, don't try to heat your house or water with solar, it's too expensive. Use propane, natural gas or some other energy source for that.

I don't get why you would go from solar to electricity to heat - lots of conversions to lose on - you'll end up with something under 10% efficiency. You would be much better off heating the water directly from the sun. Either build-yourself (batch heater is the simplest - basically a black tank inside an insulated box with a double glazed front facing the sun - better still if you can close an insulated lid at night). Or buy a solar water system in kit or completed form - evacuated tubes best (and most $$).

For wind power you can get very good efficency - high 90% - from mechanical directly to electrical. The least number of steps between the wind turbine and the heating element the better.

By the way, for inspiration, google Drake's Landing Solar Community...

Good answer, I will rate you for an on topic answer as well....

This seems like a very expensive and complicated method to save money.

Would it not be simpler to install a wood-fired boiler? If you are truly cheap you can scavenge your fuel source from shipping pallets or other discarded burnable materials.

Wood, wood pellets, corn or Maize burning is CO2 neutral and will achieve what the original poster wants.....

Yours was a good answer, I will rate it so.

First! Are you getting free fuel to run the generator?

Second! If you are going to use a generator to make electricity to heat hot water! Why not use the hot water from the generator to heat the floor and the electricity to power the building? Hence the theory of "Co-Generation," using all the available forms of energy derived from the conbustion of fuel to power the prime mover "engine" including exhaust heat recovery.

Third! It's cheaper to use a fossil fuel fired boiler and more efficient to make hot water for the purpose then to run a generator to make hot water via electricity unless you can recover all the heat energy...and it cost a lot of money to do this.

Remember! There is no free lunch when it come to energy.

Remember! There is no free lunch when it come to energy.

are you sure ? i think there is lots of ways to get a free lunch and free energy you just have to unlearn all that they have made you think was right and take a different path.

remeber that all the gens we have now are from the late 1800's and no one has questioned all the losses

LOL!

That's right. Free energy is available from the Rings of Power. Nine were given to Men, 7 to Dwarves, 3 to Elves etc. We must somehow learn to tap into this power to run the modern world.

Now if I could just find an Elf somewhere....

What runs the generator? As said, solar collectors can be more expensive for the amount of heat produced in a 24 hr period than more conventional systems. An open flame with a forced draft is very clean. If you have access to a biofuel that is great, but even using fossil fuels you would use less energy by using the heat directly. Changing the heat to electricity and then back to heat involves losses in energy.

Now if you want electricity and want to use the waste heat to heat your garage, then build a steam powered generator. The water-tube boiler is the safest type and one 30" in dia. and about 15 in high will run a 20 hp steam engine to power a generator. You have waste heat from the exhaust and from the used steam, which has to be condensed, to be reused. Circulating cold water from the floor to cool the condenser and exhaust will give you warm water to run under the floor.

The fuel to operate the boiler can be anything that burns, but liquid or gaseous fuels are easier to use. A solar boiler can be made using a large rectangular parabolic reflector, that is automated and powered to turn with the sun, with a helical tubing at the focal point. The heat can be stored in insulated tanks. Or you could use the steam to make electricity. The only drawback is that on the cold winter night it's dark and you can't use the solar collector and the floor gets cold when your storage tanks get used up. No drawbacks with a steam system as long as you have fuel. Maybe a combined solar boiler and fueled boiler, a hybrid system would work better to make electricity and heat. Whatever, it will not be cheap.

See - Green Steam Engine, Lynx Steam, Cyclone Steam, Mike Brown Steam engines and Tesla Turbines. You may get some ideas there.

im thinking... use the generator to charge the batteries, run the circulator pump, power the water heater, use solar to heat the water on sunny days, possibly a 40 gallon insulated(very) reserve/holding tank. might work, eh?

You need to consider the amount of energy you require to heat the space. I have a wood heater rated at 45,000 BTU per hour - approximately 13,000 joules per second or 13 kilowatts. This would keep your room toasty - probably wouldn't need anything like full output, so call it 5,000 watts.

If you applied 5,000 watts (that's 5,000 joules per second) to your 40 gallon (150 litre) water tank, it would heat up about 30 degrees C per hour. So after a bit less than three hours it would be boiling.

Go back the other way - to heat your room releasing that stored heat at 5,000 watts, start with 40 gallons of boiling water (you won't have it boiling though) and you'll get less than 3 hours of effective heat from it before you've exhausted - or dissipated - the stored energy.

So you'll more than likely want to store more than 40 gallons, plus you'll need a lot of solar panels to provide the heat in the first place. You get something like 100w per square metre depending on where you live - so you would need 50 square metres to get 5000 watts during the sunny hours. (Although allowing for efficiency losses, you will get less than this).

But if you had 8-9 hours of sunshine, more than 50 sq m of solar panels, some wind generation and four 40 gallon tanks, you might get six good hours of heating back each night.

Don't forget that burning wood can be carbon neutral (it's cycling atmospheric carbon, not releasing sequestered carbon like fossil fuels do). For your trouble you might be better off getting a wood stove with a water jacket, running it efficiently and heating your domestic hot water that way - or even piping around the house though radiators.

Happy tinkering...

By the way - a good way to check your heating requirements is to put a free standing electric heater with variable wattage in the room - these can usually be set to 900, 1500 or 2400 watts. Turn it on 900 watts with the thermostat on full - if the room gets hot enough then you can use something less than a kilowatt in your calculations as your requirement for that room. If it doesn't, try the other wattage settings...

It's unlikely you'll need the 5000 watts mentioned in my previous post unless it's a really big room - but with a home-built, green-powered heating system you will want to serously overengineer as you won't get great efficiency, and you'll be really ticked off to have spent hundreds of hours building a system that produces a small dribble of warm air.

Good and accurate. I will rate your post as on topic.

hello all!! great comments, gives me food for thought! just thought i would give an update on said project, i have scored an ametek 38 volt perm. magnet dc motor/gen. and a t.v. antenna mast which is 12 feet tall, so if i mount my 'wind catcher' on that on top of my garage roof, i should be approx 25 feet above the ground. i am considering building a heat box to mount to my roof as i have all day southern exposure, plus i have some good size thermal payne windows. the floor i would be heating is 22' x 26' so it isn't a real big area, if i can achieve 45-55 degrees on average, that would be good.

Sounds great

- watch the wind load - your tv antenna mast might need some good reinforcing as it probably wasn't designed for a load with potentially large gyroscopic forces (ie if your spinning propeller gets a gust across the fin that forces it to turn on its vertical axis out of the plane it's spinning in, a resulting load on your tower will be along a horizontal axis - ie will be a bending force on the mast. You're probably aware of this - but if not, take a front wheel out of a bicycle and turn your body while holding the spinning wheel by the ends of its axles to get a sense of this force (do this carefully if the wheel is spinning fast)).

- you might want to google "The Integral Passive Solar Water Heater Book" by David Bainbridge. It's a free download now that it's gone out of print. Everything you need to know about building your heat box.

- keep us informed!

I hate to be rude, but I somehow feel that you may not have understood some of the help you have been given......what you have planned might just keep a few goldfish warm in a not too big Aquarium, but that is probably about it.....

Most of the early posts actually gave you working information that would show that you can probably keep a few car batteries charged up for infrequent usage with the size of the charge that you may get, but to heat an area as large as you mention, you are really in for a surprise!

I must also add that I fully understand if you feel that the only way to find out is a DIY attitude, please go ahead (in spite of my comments) and I wish you all the luck in the world, but do not get dismayed if it does not quite work as well as you obviously hope it will.... We are all interested in a) helping you b) your success

Try the following links for some really simple ideas to take solar energy that may do what you want to heat a space in winter time:-

http://www.bigginhill.co.uk/solar.htm

almost-free-garage-heat-just-drink-a-lot-of-soda

Do not forget that the space you want to warm up should be as well insulated (no drafts or holes) as possible so as to make full use of the energy collected, no matter how it is collected....

Keep us informed on the results....

It would appear that Stepper motors make good brushless dynamos and are relatively efficient.

I have not tried this personally though and I do not know if the output is DC or AC, but I would guess at AC.....

They come in many sizes too....