Old habits are hard to break

I would to start this thread to make a list of ideas that challenge the status quo of the way we do things regarding energy consumption.

To start off I ask the question, why do we continue to  burn natural gas and propane to atmosphere in  order to extract the energy from it?

Much more useful work can be achieved by burning under compression.  One solution I have been kicking around in my head is replacing the 90% efficiency furnace (90% of 50% of the work possible is 45% in actuality) with an internal combustion engine running a  generator. The waste heat would be a byproduct that could be used in a radiant floor loop. The electricity generated can be sent to baseboard heating with thermal mass to reduce cycling. How many times a day would it request heat? I bet in a well insulated home it would be twice a day? A furnace cycles 2-3 times an hour. Even if it cycles 4 or 5 times a day what would the cost be compared to burning to atmosphere?

I have an electric start honda es65 and it is amazingly quiet. Liquid cooled as well. Thinking of...if it were to be in a basement in an insulated air tight enclosure with external combustion air and exhaust obviously, with rigorous safety measures to shut down in the event of CO or CO² build up in the event of a blown headgasket or exhaust leak. Obviously it could be outside as most backup gensets are. Emergency power always available and eliminating an appliance from the structure. 90% furnaces seem to be quite failure prone as well. Sure the engine will need maintenance ...but converting away from gasoline results in much less frequent oil changes.


Please expound on this idea or add a new one to discuss if you aren't guarding the idea for future income!

I love this idea.
I've considered capturing waste heat via co-generation, but for some reason,  the electric heating portion never occurred to me.
The best part is the efficiency of the generator isn't terribly important.
As long as it burns all of the propane or natural gas, there is no waste heat, just heat.

Even in the summer, you could use this for domestic hot water.

Dont forget in Summer it may be better to have solar hot water via flat plates.

I like the strategy in thinking.
Even a heat exchanger on the exhaust would help if its possible.

It's an interesting idea, with challenges.

Co-generation has been used in industry for decades, especially for facilities being contructed in places where natural gas infrastructure was handy but the electrical was too far away for an economical hookup (they would pay the whole cost for new lines).

For a time, a local utility even offered units for homes, based on a Stirling engine. I know the upfront cost was substantial (far beyond my means). I have no idea how many takers they had.

For individual property owners, though, I believe the barriers are many. If you're building from scratch with no existing infrastructure, it may have merit. If you already have electrical infrastructure on site, you pay for it whether it's actively used or not. Or, pay to have it removed -- if the municipality would let you.

I wonder, what would the impact be in a city? A lot more natural gas would be burned locally.

ben heidorn wrote:I would to start this thread to make a list of ideas that challenge the status quo of the way we do things regarding energy consumption.

To start off I ask the question, why do we continue to  burn natural gas and propane to atmosphere in  order to extract the energy from it?

Much more useful work can be achieved by burning under compression.  One solution I have been kicking around in my head is replacing the 90% efficiency furnace (90% of 50% of the work possible is 45% in actuality) with an internal combustion engine running a  generator. The waste heat would be a byproduct that could be used in a radiant floor loop. The electricity generated can be sent to baseboard heating with thermal mass to reduce cycling. How many times a day would it request heat? I bet in a well insulated home it would be twice a day? A furnace cycles 2-3 times an hour. Even if it cycles 4 or 5 times a day what would the cost be compared to burning to atmosphere?

I have an electric start honda es65 and it is amazingly quiet. Liquid cooled as well. Thinking of...if it were to be in a basement in an insulated air tight enclosure with external combustion air and exhaust obviously, with rigorous safety measures to shut down in the event of CO or CO² build up in the event of a blown headgasket or exhaust leak. Obviously it could be outside as most backup gensets are. Emergency power always available and eliminating an appliance from the structure. 90% furnaces seem to be quite failure prone as well. Sure the engine will need maintenance ...but converting away from gasoline results in much less frequent oil changes.


Please expound on this idea or add a new one to discuss if you aren't guarding the idea for future income!

cogeneration  is popular in the wood gasification world and the diesel world as well...
There are challenges. You have a water cooled engine that is a good start but you will have to try to capture the exhaust for better efficiency. It roughly breaks down to 25 percent energy in fuel to electricity plus or minus, 25 engine heat 25 exhaust and 25 percent noise, vibration, friction, and uncapturables... I played around in that world a bit. If you are serious about small engine cogeneration done at home check out these guys https://www.microcogen.info/index.php
They mostly do diesels but there is some nat gas and propane content as well...
Cheers,  David

Here in New England, the wintertime is the most common for electrical outages. Heavy wet snow or ice storms causing trees to fall on transmission lines. So, there's a need for heat at the same time. Having a backup generator that provides power to run HVAC equipment is good, but it would be pretty slick to capture the waste heat. There's also a weekly "exercise" cycle that keeps things charged and lubricated that goes "to waste", so to speak (beyond the value of "the exercise"). Both coolant heat and "exercise" electricity could get "dumped" into a domestic hot water heater fairly easily, and could even be scheduled for maximum effect.

I guess an important question would be: Are the engine coolant and hydronic heating loop within compatible temperature ranges? Most ICE's are designed to operate within a particular temperature range, for valve/piston clearances and oil viscosity.
Could the engine properly reject heat into a 140*F DHW heater? (engine overheats)
Would a radiant heat loop in a cold slab cool the engine coolant too much? (engine doesn't reach 'normal operating temperature')
Would a remote radiator/fan location to heat indoor air be better?

I guess it all comes down to sizing the components properly. I'm curious about sizing the generator. Would it need to be able to cover the heating load solely by electric? or less, by factoring in the waste heat?
What about a back-up electric needs? I imagine those could be "constant" needs, so the generator would run all the time to cover those , rather than cycling on/off like it would be in heating mode.

Another thing to consider is lifespan (hours on engine) and what a breakdown/repair involves in time/cost/availability/complexity/skill?

John C Daley wrote:Dont forget in Summer it may be better to have solar hot water via flat plates.

I like the strategy in thinking.
Even a heat exchanger on the exhaust would help if its possible.

Absolutely perhaps a catalyst as well before the exchanger. You could get into the realm of extracting most of the heat where a condensate pump would be required.

Douglas Alpenstock wrote:It's an interesting idea, with challenges.
For individual property owners, though, I believe the barriers are many. If you're building from scratch with no existing infrastructure, it may have merit. If you already have electrical infrastructure on site, you pay for it whether it's actively used or not. Or, pay to have it removed -- if the municipality would let you.

I wonder, what would the impact be in a city? A lot more natural gas would be burned locally.

Doug I would intend for it to be entirely separate from the grid. Mains for the house would still be grid tied. Except during an outage a transfer switch could power the home in an emergency.


Thank you for the link David I will check it out when I get some Wi-Fi.

William Bronson wrote: I love this idea.
I've considered capturing waste heat via co-generation, but for some reason,  the electric heating portion never occurred to me.
The best part is the efficiency of the generator isn't terribly important.
As long as it burns all of the propane or natural gas, there is no waste heat, just heat.

Even in the summer, you could use this for domestic hot water.

William I would intend for it to be idle in the summer except during an emergency  when a transfer switch could be engaged.  I once met a fellow that had an oil well on his property that is controlled by someone that leased it before he purchased the property.  His share of the lease nets him around 600 dollars a year and has been declining.  The well vents natural gas to atmosphere in order to bring up the oil. His main benefit is tapping in to the gas source for home heat. In a situation like this a large generator supplying all of his needs would be beneficial for him and the environment. I doubt there would be a need for alternate heat source in this application though.

Haha Kenneth your signature really  HITS home!

Doug ...It seems the Stirling cycle is way more advanced than the  little hobby ones that are showcased. I don't often  see the technology used to its full potential.

Why do we do so much of what we do?

I recently did a podcast episode on habits...

...specifically how long it takes to form new habits.

Are you interested in how long it takes to develop a new habit in life?  

Join me in a discussion on new habits and the mentality required to implement them in your life...

https://www.buzzsprout.com/650959/episodes/6181525