CHP = Combined Heating & Power...
 

A few years ago, a good friend of mine who worked for the Oregon Dept of Energy took a trip to Freiburg, Germany, so see some of the innovative things going on there.

One of the most interesting ideas he saw was an apartment building which was very well insulated, and which derived all of it's heating and electrical power from a Ford V-8 in the basement, probably running on Natural Gas. I didn't know it at the time but what he was describing was a CHP (Combined Heating & Power) setup (AKA: CoGeneration).

Unfortunately I don't have a photo of it. However, the engine is hooked to a generator, and the heat from the cooling water and from the exhaust (normally thought of as 'wasted energy') is used for building heat.

In fact the setup was designed so that when the Ford V-8 was running harder in the chilly German evenings, the extra electrical power generated by the CHP was sold back to the power companies.

Here is a report of CHP activities going on in Mississippi, with photos:

http://www.propane.tx.gov/research/d...CHPSystems.pdf

Here's a picture from it:


Looks to me that if a small unit CHP unit were combined with a heat pump, it would be very efficient, indeed.

A water-cooled generator would be quieter and last longer, and the heated water would be easier to handle and store... could even run it through a hydronic floor heat system.

The trick is to find a small, sturdy water cooled engine...


Here's a link to a very interesting small engine, water-cooled, propane/natural gas powered generator that is designed for heavy use.

And here's a monster link for further inquiry.

And I did find conversion kits to change over small generator engines to Propane & Natural Gas

Here

And Here

But, locating a small, sturdy engine that's water-cooled, hmmm.....

As further food for thought, a Ton of AC = 12,000 BTU/hr = 4.715 hp

Regards,

-AC_Hacker

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Connect a small car engine to an industrial electric motor, then add heat exchangers to recover as much heat as you can. If you spin an induction motor above synchronous speed, it becomes a generator.

Further
 

Good start, now carry it further...

If you were to estimate the gallons used per hour of your hypothetical setup(imagine small car mileage) then convert it to BTUs you might have a useful idea of the total heat & electrical power output. Figure maybe 10% to 15% efficiency for the electricity generated and 85% to 90% efficiency for the heat portion.

Or, just use power bills to know the amount of power you and your co-consumer use per day, and figure backwards to the fuel rate and engine size required.

See? Then it starts to get interesting...

-AC_Hacker

PS: As for myself, I'm thinking along the line of an older, small, 2 cyl, low rpm marine engine.

People already make DIY home-scale cogeneration projects with an old IC engine running on anything from veggie oil to gassified wood. But the problem with an IC engine is that, well, it's internal combustion. This means that

• It's complicated,
• There is a lot of stress on the parts,
• The fuel must be very clean so nothing deposits inside the engine.

Using a stirling engine is much simpler and allows the combustion to happen externally. There is a discussion on exhaust heat recovery using steam power over at EcoModder.com, which has steered towards stirling engines.

I found a natural gas fired prototype home cogeneration unit:
De Dietrich Remeha – Das Unternehmen
Google translation from German
Kocioł 2w1 - ogrzewanie i równoczesne wytwarzanie prądu
Google translation from Polish

http://www.bhkw-prinz.de/wp-content/...-1024x1024.jpg

This is a nat gas condensing furnace (107% efficiency) with a stirling engine running a 1kW generator. Producing 1kW of electricity also produces 5kW of heat energy, with the option for more heat if needed. It was supposed to be on sale here in 2010, for about 15,000 €, but I haven't found it anywhere.

Co-gen = Slow-gen
 

This is great info.

I searched but could not find anything that was not industrial size for sale.


This kind of thing may show up in Europe sooner than in the US (we're too busy dropping bombs to develop efficient home heating).

Let us know if anything turns up.

-AC_Hacker

freewatt
 

This has been available in the northeast US for a few years now.
Freewatt Eco-Friendly Heating & Power Systems

Based on a small Honda CNG engine sounds like a good idea, just too expensive for me.

Looks like they are for sale, but not anything in my neck of the woods.


But here's a PDF of the Honda Micro CNG...

The PDF says it's a 163 cc vertical shaft water-cooled engine. That should give us some inkling of an engine size for a tiny Co-Gen.


And here's an Ebay link for natural gas & propane carb from 1.5 HP and above.

Now we need to find a very small, highly reliable water cooled engine, and some kind of dynamo. Looks like the design of the exhaust gas heat recuperator is also pretty sophisticated, since it scavanges not only the sensible heat but also the latent heat of vaporization (condensing heat recovery).

-AC_Hacker

46.5cc water-coled engine...
 

I did come across a very small water-cooled engine:


And here are the specs:

46.5cc,2-stroke,water-cooled,pull-start gasoline Engine

Specifications:
1) Engine type: single-cylinder, 2-stroke, water-cooled
2) Piston displacement: 46.5cc
3) Bore x stroke: 39.5 x 37 mm
4) Max. torque: 5.8N.m/12,000rpm
5) Max. power: 6.0KW/11,000rpm
6) Min. idle rotate speed: 3,500rpm
7) Compression ratio: 9.0:1
8) Ignition: CDI
9) Spark plug: Torch
10) Carburetor: diaphragm
11) Air filter: polyurethane foam
12) Start mode: pull-start
13) Clutch style: adjustable centrifugal automatic
14) Average fuel consumption: 610g/kWh
15) Dimensions: 400x210x230 mm
16) N.W.: 5.5kg

So if the max power is 6 KW, then it might be reasonable to expect about half of that (3 KW) on a long term basis.


If the unit was mated to a pancake generator similiar to one that the Honda CNG uses, the generator would also function as a starter motor. My hybrid car has a similar generator built into the flywheel, that functions like a starter, and it works better than any starter I have experienced.

So if the electrical generation was around 15% efficient (not unreasonable), we could get about 450 Watts of power. And if we could capture 60% of the 'wasted' heat energy, we would have 1530 watts of heat energy or 5220.36 BTUs.

Those energy levels would be in excess of my non-peak home energy consumption, which means I could sell energy back to the power company.

Not bad for a 46cc engine.

-AC_Hacker

I think 2 strokes are less efficient than 4 strokes.