Wednesday, June 29, 2005

New idea - microgenerating hot water heater

[See previous]

This article is rather obscure, but buried inside of it is one small paragraph that defines a new idea: Micro-power hailed as cheap, safe energy of future: "The report says 1 million new gas-fired boilers are installed every year in the UK. If half these boilers micro-combined heat and power they would produce the equivalent electricity of a new power station each year, removing the need for new large-scale power plants."

You can see what the paragraph is getting at. Currently, if you buy a new water heater that burns natural gas, what you get is simply a water heater. What if, instead, the water heater contained a natural-gas-powered electric generator, and the excess heat produced by this generator heated the hot water?

Since 80% of the energy consumed by a gas-powered generator like this is waste heat anyway, you capture the waste heat to heat your hot water and get the electricity, essentially, for free. You could do the same thing with any natural gas furnace.

Let's say that your water heater currently runs for one hour per day. During that one hour, you would be producing, say, five kilowatt-hours of electricity. You would use the electricity yourself, or sell it back to the grid. Let's say electricity costs 10 cents per kilowatt-hour, so now your water heater is making you 50 cents per day, or about $180 per year. A typical water heater costs about $900 installed, and lasts about 10 years. So, your water heater makes you $1,800 over its 10-year lifespan.

Obviously a water heater that contains an electrical generator is going to cost more than a "standard" water heater. Let's say that adding the generator (plus its maintenance and the new wiring) doubles the price of the installed water heater, from $900 to $1,800. The upside is that you get your water heater for free. Instead of your water heater "costing you $900", your water heater is free over its 10-year lifespan.

You could do the same with a gas-fired furnace. However, in the winter months, a gas-fired furnace runs more than an hour a day. Therefore you would end up making more money from the electricity that your furnace produces.

Comments:
Do you have any idea what the actual numbers are for the prices involved?
At any rate, I suspect that overcoming inertia makes this idea impractical for the developed world. It's probably more feasible in a poor country where the money saved would matter more. A good item to buy with microcredit for instance.
 
Cogenerating furnaces and water heaters?

Been there - blogged that.

The problem with cogenerators is that their ideal fuels, natural gas and fuel oil, are also the ones going into rapid decline.  (This appears to be happening much more rapidly than I expected.)  It's going to be very important to adopt an integrated approach to heat and electric generation:  replace most simple furnaces and water heaters with cogenerating units with electric supplemental heat while adding wind power to the grid as fast as practical.  Also push toward IGCC powerplants to replace atmospheric powdered-coal boilers, and pipe some of the syngas off to make up for declining supplies of natural gas.  Burn gas (both natural and syngas) in engines or microturbines with heat recovery so that roughly half of the electric generation is replaced.

If we leverage these things well enough, we can buy a couple of decades.  Unfortunately, I see lots of social and regulatory barriers in the way.  For instance, EPA rules may not allow cogenerating furnaces and water heaters to connect to the grid if they do not meet emissions standards.  I'm all for clean air, but photochemical smog is a heat-related phenomenon; holding to summer standards during a cold snap is between ignorant and insane.
 
Here's the most recent development on this front:

http://www.boston.com/business/articles/2005/04/26/honda_collaborates_on_a_hybrid_for_the_home/

First paragraphs (see article for more):

American Honda Motor Co., which has been working on hybrid cars, is collaborating on a hybrid of sorts for the home: a roughly $8,000 natural gas system that ''co-generates" heat and electricity.

For consumers willing to invest $3,000 to $4,000 more than the cost of a conventional heating system, there's a potential for savings when it comes to paying energy bills down the road, according to Climate Energy LLC of Medfield, one of Honda's partners. With the new system, called a Micro-CHP System, natural gas that home owners buy to convert to heat creates electricity as a bonus byproduct.

At an event set for today at the Museum of Science, Climate Energy, and Honda plan to unveil a combined heat-and-power appliance that Climate Energy claims can shave about $600 off a local consumer's annual electricity bill.

According to the two companies, this is the first time such an appliance will be available at affordable prices to US home owners.
 
Blogged that too.  Verdict:  it's undersized.
 
Having just got back from japan, Where they are using these microgenerators in new construction, the idea is approached differently. They market it based on the fact that on demand water heaters are not efficient, so why not use that wasted energy for something useful?
It helps that electricity and gas are nearly double what they are in the USA. the whole system, in japan, includes the honda generator, a heat exchanger, coils for the bath, radiant floor heating, and an output for domestic hot water. There is also a second coil for additional hot water if the generator can't meet the short-term needs. Overall installed cost is about $8,000, and the utility suggests a cost savings on utilities of 40%/year.
 
Excellent article. These are great suggestions, but i just don't see it happening since the corporations and utility companies don't care about us saving energy or money. 50 years down the line however, i think it may become a more prevalent issue. Keep up the blogging!
 
Heaters are always evolving with the increase in technology it is the same with a/c, it is not so long a go that they were huge units but the latest chip technology allows for portable air conditioning units that are small and compact and can be used almost anywhere.
 
I like this idea!!! if this micro-power can help us to save energy and money is really good for me. I will see if i can installed in my home.
 
Hi,

You have got a pleasant blog with informative articles. Many thanks for being so informative about steam boilers.
 
If you're buying a water tank for ongoing use, such as in an RV or boat, you'll want something that's a little heavier duty than if you're just using it for emergency situations, such as when the power goes out due to storms or some other reason. In those cases, the hot water heater likely isn't going to have to provide you with water for any significant length of time.
 
They can work with existing central heating systems or underfloor heating. Heat pumps do require some electricity to run, but with conversion efficiencies of between 300 and 500% (meaning that, for every unit of electricity used, you get 3 to 5 units of heat). With this is it efficient and a renewable way to heat your home?
 
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