# Micro CHP



## j00fek (Nov 30, 2008)

been looking into these systems since they were out last yr. since then they have come out with a hydronic water system. 

does anyone have any resources to these products? any one have one?


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## Redox (Dec 1, 2008)

Are you talking about the Marathon?

http://www.marathonengine.com/index.html

I remember when York came out with this in a heat pump back in the '90s.  It seemed like a good idea at the time, but never caught on as gas was cheap back then.  I've argued the benefits of micro CHP with a few engineers, most of whom thought that it would never pay off due to the economies of scale.  I am seeing more interest in the industrial world, FWIW.  Now that the technology has a name, it's Googlable!  I see there's a company in MA working on it also.

http://www.freewatt.com/index.asp

Years ago, I remember reading about GM/Fiat working on a system that used a 4 cyl car engine as the power source.  I guess it, too never panned out.  Maybe now is the time?  90% thermal efficiency and free electricity sure would be nice...

Chris


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## j00fek (Dec 1, 2008)

i have been looking into the honda setups from freewatt, back last yr they were climate energy. first they only had a forced hot air system, but now they have the hydronic setup. my brother is looking at having them come up and do an eval at his house. he wants to get rid of his oil burner (which is only 4.5 yrs old) and switch to an american drilled commodity (nat. gas).


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## velvetfoot (Dec 1, 2008)

I do not have any knowledge of these, but to continue the discussion anyway...
Would this setup fire up only when there is a need for heat, kind of like the oil burner?
Then it would send the power to the grid, so that the electric supply to the grid would be intermittant?
At least this way it wouldn't be running that much.  I can't imagine keeping a little Honda engine running 24x7 would ultimately be a winner.
Can this thing be islanded so that you can have backup power?


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## Highbeam (Dec 1, 2008)

With a net metering setup, the intermittent electric supply would be fine. Off grid would need to supply their battery bank with the burst of juice.


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## j00fek (Dec 2, 2008)

velvetfoot said:
			
		

> I do not have any knowledge of these, but to continue the discussion anyway...
> Would this setup fire up only when there is a need for heat, kind of like the oil burner?
> Then it would send the power to the grid, so that the electric supply to the grid would be intermittant?
> At least this way it wouldn't be running that much.  I can't imagine keeping a little Honda engine running 24x7 would ultimately be a winner.
> Can this thing be islanded so that you can have backup power?



this is a good question, i would think that it acts just like an oil burner keep the water at certain temps, and you would probably get the most out of it during the winter here in maine id think.


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## velvetfoot (Dec 2, 2008)

It would probably last longer that way, cycling on and off.
I wonder though if it would cool down much between cycles, causing inefficiencies, maybe wear?
Maybe it wouldn't be too efficient in the summer for just heating water. 
If the thermostat or water heater was satisifed, if the engine was kept running you'd have to have another way to remove the heat, like a radiator.


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## Redox (Dec 2, 2008)

I think you can do pretty much all of the above.  As a heating source, it is variable speed and thus variable output.  Perhaps start it in the early AM to heat things up, idle it all day to keep your refrigerator running and bank up on some DHW, faster in the evening to run more lights and appliances, shutdown at night to save wear and tear.  The possibilities are endless. 

The York heat pump version ran pretty much 24/7 and varied its speed to match the load.  If you are going to burn something, might as well do it in an engine.  I speculate that there will only be a passing interest in these forums as most of us are getting completely away from gas and oil as heat sources.  It will be hard to convince Harry Homeowner to spend $10k (a wild guess) on something like this, unless oil goes back to $4 a gallon.

Chris


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## j00fek (Dec 2, 2008)

this system is more like 20-30k, the ROI is 20% yr, but im not sure if they based that on $4 oil. i wouldn't mind this system running off nat. gas, i dont think solar would produce enough even in the winter months here. though i dont now how solar works in the winter with shorter sun time and diff angles due to the earths rotation.

if anyone wants a look here are the tech specs... http://www.freewatt.com/Support/SupportDocs/freewatt_hyrdonic_techspec.pdf


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## firefighterjake (Dec 2, 2008)

j00fek said:
			
		

> i have been looking into the honda setups from freewatt, back last yr they were climate energy. first they only had a forced hot air system, but now they have the hydronic setup. my brother is looking at having them come up and do an eval at his house. he wants to get rid of his oil burner (which is only 4.5 yrs old) and switch to an american drilled commodity (nat. gas).



Is your brother looking at replacing the entire boiler or just switching over the burner? Right now here in Maine there's a rather heated debate going on at the state level as the natural gas companies have been going in to homes and using the existed oil boilers with a switched nat gas. burner which is contrary to many (but not all) boiler manufacturers which are not rated or listed for that specific use (many larger boilers however can be switched over pretty easily with no issues as many of these larger boilers found in commercial occupancies are listed for multi-fuels). The natural gas company has stated that even if the appliance is not listed, it's OK since the nat. gas burns cleaner and at a lower temp . . . which concerns many Inspectors and the Fire Marshal's Office as they are a bit leary of signing off on these installations.

Here in Bangor the FMO, Bangor Fire Inspector and Bangor Gas Co. have apparently reached a tentative arrangement where the Inspector will sign off on the switch over . . . but home owners who take out a permit also receive a letter stating that doing so may void their boiler warranty if this is not a listed and approved use.


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## j00fek (Dec 2, 2008)

looking to take the whole boiler,tank(s) setup out and put another heating,DHW source.


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## Redox (Dec 4, 2008)

j00fek said:
			
		

> this system is more like 20-30k, the ROI is 20% yr, but im not sure if they based that on $4 oil. i wouldn't mind this system running off nat. gas, i dont think solar would produce enough even in the winter months here. though i dont now how solar works in the winter with shorter sun time and diff angles due to the earths rotation.
> 
> if anyone wants a look here are the tech specs... http://www.freewatt.com/Support/SupportDocs/freewatt_hyrdonic_techspec.pdf



Just thinking about this subject and looking over the specs.  The Freewatt is basically a very efficient 1.2KW gas fired generator that is only capable of 12,000 BTUs of heating capacity.  If you need more heat than that, you are going to be running another boiler.  Similarly, if you need more than 1200 watts to your home, you are going to be buying it from the utility.  I think this might cover maybe 1/2 of my typical monthly electricity consumption and maybe 1/4 of what my stove is capable of putting out (a guess).  Just doesn't sound justifiable, especially for $25k, unless I am missing something.

Since math was never my strong subject, let me throw a few numbers out there and see if they make sense.  From FW's spec page, it burns 18,500 BTUs of gas to make 12,000 BTUs of heat.  That's 65% efficient.  OK, I believe that; an IC engine is supposed to be 20-30% efficient at best.  If it were a 95% efficient boiler, it would take 12,600 BTUs to do the same work, but you are generating 1200 watts of electricity at the same time.  Using $1.50/therm and $0.15/KWH as reasonable fuel costs, it would burn 5900 BTUs additional gas or 0.059 therms costing you 8.85 cents to generate 1200 watts that ordinarily would cost you 18 cents to buy from the utility.  So, you are saving 9.15 cents for every hour it operates.  Right?  Multiply it out and assume it runs continuously from Oct to Apr and you get an annual fuel savings of about $460.  A $20k investment in this generator would take about 43 years to break even at todays energy costs not counting the maintenance on an internal combustion engine.  Am I missing something here?

I think I'd stick with one of the new modulating condensing boilers for now if I needed to upgrade.  That'll get you 90%+ efficiency on the heat and take your licks on the electricity.  If your BIL's boiler is only 4-5 years old, he isn't going to save much, unless oil shoots back up to $4/gal again.  FWIW, NG isn't dropping off nearly like oil is right now.  It seems to me that there is really no ground breaking technology going on with the Freewatt.  I'm sure there is a proprietary controller, but it is basically an overdesigned liquid cooled generator and a grid tied inverter.  Granted, it has a closed loop fuel system and a catcon, but still...

Much as I admire Honda's engineering, I don't think it will ever pay for itself before it wears out.  43 years makes solar PV look more attractive, even in a less than perfect setup in New England!

Comments?

Chris


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