Combined heat and generation tech for home

An interesting technology long used in industrial/commercial settings that is coming to the home. "Combined heat and generation" units can replace your home furnace. A natural gas-powered generator produces electricity, and the waste heat is then piped through the home for heating purposes. Although the unit costs approximately $13,000, the cost savings in electricity can be substantial and helps to offset the higher initial cost. Excess electricity can be sold back to the utility company.

In cold climates where blizzards and ice storms can knock out the electric grid for days and weeks, a system like this would be a great benefit--well, assuming that natural gas was still being delivered. I would think that the technology could be adapted to use propane. Claimed efficiency is 90%! Wow, that's excellent! In comparison, the typical internal combustion engine is only, what, something like 30% efficient? The rest of the energy is wasted as heat.

Anyway, I read about this technology in this C/Net article.

Interesting. Although, you've got to be very careful accounting for all costs with systems like these. It took a while, but I finally found their estimated payback period on the website - at least 4 to 5 years. They talk a lot about how much electricity it will save you but nothing about how much the natural gas will cost you to run it.

My dream system, assuming I found the time to tinker with it, would be a slow-speed diesel "Lister" engine clone running a generator with its cooling system piped into my hydronic heating system and run on free waste vegetable oil.

I agree wholeheartedly with this; diesel engines are awesomely capable given their method of generation. Not to mention I've seen them run on everything from veggie oil to hard alcohol. Granted, sometimes it's not pretty but if you want a multi-fuel source engine, diesel is hard to beat.

I do like the IDEA of the natural gas system though. That is terribly expensive.. I'm sure if it gets popular maybe in a few years it will be worthwhile.

Regarding the payback period, C/Net is also running a separate article today on a company trying to make home solar systems more affordable by making them easier to assemble and install. Anyway, in that article, they report 8 years being the typical breakeven point for your typical home solar electricity-generating setup, so this system compares favorably to installing a solar system.

For a system meant to be used daily, with little muss-and-fuss, this natural gas powered system sounds great. I agree that diesel would be great, too, particularly in a pinch, but under normal circumstances, I think I would prefer the ease and clean-burning characteristics of the natural gas way. I'm thinking it would provide heat plus electricity for blackouts that don't also knock out the natural gas supplies, which probably includes most blackouts in developed areas.

Great concept. But be careful when you are checking out their payback calculations.

I checked into solar power over 10 years ago when we were building our house & I think the 8 year payback is hogwash. What the company I was looking at was leaving out was the interest you would be paying on all the extra money that you would have to borrow.

At the time the mortgage rate was at 8% & you take that times the solar setup of $30,000 which would be $200 a month in INTEREST alone. Our electric bill has never been over $125 so you would never reach a payback date. Even if the system worked flawlessly.

Interest rates are lower now so lets take current mortgage of 6% X $13,000 = $65 a month just on the interest.

This system would have a huge advantage over a solar electric alone because you would also be slashing your heating & electric bill at the same time.

After reading the article it would also be better than the solar one because it would replace the initial cost of a furnance which they said is roughly 1/2 of their system. If that's true you would only be paying off the $6,750 difference.

I'm very interested in this system. THANKS FOR THE POST.

For the break even calculations you did in the past, were you assuming that you won't have any surplus electricity from the solar setup to sell back to the utility company? Just wondering, since you didn't mention it in your calculations.

Here is an interesting article on the number of Solar Cells Needed to produce your homes electricity. They are in agreement that it is never going to payback.

The thing is our electric company has a minumum bill of $8.06 per month. So there would never be a month when I would actually get money back from them. So that nixes the idea of making extra to add to the payback.

However, that is a great point though because those original calculations by me (amateur) were based on a battery setup situation where you are completly off the grid. Which is vastly more expensive than just buying the panels. At the time I didn't know you could be wired up & let the meter run backwards during the day & then use the companies electricity during the evening.

I think the gas generator that you've listed is very possible because our current propane furnance is 90% efficient, but doesn't give us any electricity. I am going to look into this very seriously on the next house. <img src="/images/graemlins/cool.gif" alt="" /> Hopefully, it will be available for purchase in Missouri at some point.

Popular Mechanic’s site has a Blog from an individual who lives off the Grid. Solar is just part of his system along with wind and propane generator, and his family is very energy conscious.

Thanks. I will read as the idea is VERY appealing to me.

I saw a thing on Discovery channel over weekend that they are making a lot of headway towards making them vastly more efficient. Current ones only pick up a small slice of the sunlight rays & waste the rest of the solar spectrum as heat. They are trying to develop panels that will convert more of the energy to electricity. When that happens they will become much more effecient & AFFORDABLE.

While its not practical to run your whole house yet, I'm looking at a small system to run a few things off grid. Basically I'm building a small UPS without the inverter on the output side. Basically a small solar panel to charge a 12v battery which can then charge or power radios, flashlights, etc. This consolidates down batteries so I don't have to stock and rotate dozens of batteries for all my gear.

I didn't look at the photos that accompany the C/Net article I posted about yesterday, but I looked at them today and found an interesting comment on one photo. Looks like this particular company will also come out with a model that heats water instead of air later this year. I don't need a heater much where I live, but hot water is something we can all use daily. Another big plus for this product.

Again, thanks for tossing this out there.

I wonder if the thing could be Stand-Alone? So in other words if I throw the breaker at the pole outside of my house would it still be able to kick on & start heating the air (or water) & start producing electricity to keep the frig on until the power comes back on.

That would be a huge plus if it's true.

Doh! You're right. I hadn't thought of it that way.

Natural-gas powered doesn't mean it can run without any electricity. Just like my gas furnace. That's an excellent point to investigate for anyone wanting to live off the electric grid or thinking they will be immune to power outages.

at the other end of the spectrum you might find these interesting, they make (a little) electricity from waste heat.

http://www.varmaraf.is/engl/prod.htm


Lee