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Power Technology

Another Step Forward In Small Scale Electrical Generators 137

NicknamesAreStupid writes "Product Design & Development reports another breakthrough in small scale solid oxide fuel cells. This methane-fueled cell achieves about 50% efficiency at around 2kW, enough to power an average home. It does so by efficiently recycling its heat to perpetuate the process. Of course, this is not practical for most homes, which only have natural gas that contains nearly one fifth impurities. However, that could change if gas suppliers refined their product."
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Another Step Forward In Small Scale Electrical Generators

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  • How small is small? (Score:4, Interesting)

    by fahrbot-bot ( 874524 ) on Sunday June 03, 2012 @02:50PM (#40202595)
    Could it be used on board an electric vehicle to provide power in lieu of a battery?
    • by Anonymous Coward on Sunday June 03, 2012 @02:57PM (#40202645)

      Could it be used on board an electric vehicle to provide power in lieu of a battery?

      No. Even though solid oxide fuel cells work and are commercially available (in larger sizes), they have problems for automobile applications - to run efficiently, they operate close to 1000 degrees C, and they don't like being bounced around. Dealing with that kind of temperature in a car is a problem.

      For mobile applications, PEM fuel cells [] are far more likely to be practical.

      • by Anonymous Coward

        Yeah, but you need a lot of platinum for those (though it has been reduced in recent years). Hmm. Who can we invade? Zimbabwe has lots of platinum. We could even say that we're doing it to give them freedom!

      • by barv ( 1382797 )

        "they operate close to 1000 degrees C, and they don't like being bounced around. Dealing with that kind of temperature in a car is a problem."

        Gosh. You mean my diesel cycle runs at less than 1000 deg C?

        • by Anonymous Coward

          Yes, but your diesel engine can start making power at 20 C or 0 C and sometimes -20 C. The fuel cell will not make power until it is over 500 C. And due to its mechanics and design, it would take an hour heat up to that temperature and longer to its peak efficiency. It might be plausible for a semi-truck, but for most vehicles this delay would be too long.

        • by Amouth ( 879122 )

          Your diesel runs significantly less than 1000 deg C. most run at ~550C or less.

          • "Your diesel runs significantly less than 1000 deg C. most run at ~550C or less."

            For instance look at figures 5 and 6. []

            Maximum cycle temperatures for a diesel are shown as between 1500K and 2100K which is 1200C to 1800C

            On a theoretic basis, that is what gives a diesel such a high thermal efficiency.

            • by Amouth ( 879122 )

              You do realize that that document is talking about pure theory and theoretical maximums? In reality the operational temperature of you diesel engine is far lower, the 550C is the ignition temp while the actual motor temp is closer to 100-150C.

              Also note that isn't why diesel has a higher thermal efficiency in an ICE environment, but rather it's increased efficiency is because of how and when the fuel is added to the cylinder and the ignition mechanism which enables much higher compression ratios than are pos

              • by barv ( 1382797 )

                Working from memories a few decades old...

                Carnot applies. Max.Eth = 1 - Tlow/Thi

                Where Max.Eth = maximum theoretical thermal efficiency.
                Tlow = sink temperature (exhaust temp in K or R.)
                Thi. = Max cycle temp (just after explosion/injection finishes)

                So what you are saying is a mechanics explanation. There is nothing theoretical in my figures. The temperature inside the cylinder easily exceeds 1000C. What I have stated is the physical law that governs the theoretical maximum efficiency. Carnot applies to

                • by Amouth ( 879122 )

                  I understand what you are saying but, if we are going to start calling peek temperature in the chamber as operating temp then i'd like to point out that the temperature of the spark from the plug is ~50-60,000C.

                  Why is this argument important? because while sure you might reach 1000C for a moment inside your diesel cylinder the overall operating temperature of the diesel engine is significantly lower than that. But for a fuel cell application the operational temperature is the actual continuous temperature

                  • by barv ( 1382797 )

                    Maximum spark temperature is about 500C not 50,000C
                    see e.g. []

                    "in which case 1000C is extremely hard to manage in something the size of a normal motor."

                    I have not seen details of the size and weight (power density) of this electric generator. And it will also need an electric motor if it's going into an automobile. OTOH a temperature of 1000C is not so hard to manage (with e.g. ceramics) if the stresses are not high

                    • by Amouth ( 879122 )

                      Again your link is to something different than what i said, that temperature is for the operating (think constant) temperature of the plug it's self, not the spark it creates. Just like the operating temperature (think constant) for your diesel motor is a lot less than the burn temp of the vapor.

                      Again "Operating" temperature is constant a "cycle" temperature is just that, a cycle and not constant.

                      For fuel sell Operating and Cycle temperature are the same as it is one continuous long cycle while it is oper

                    • Well, he's still right: managing 1000 degrees C when you don't need internal moving parts is a very different question to managing the moving cylinders in an engine. A solid-oxide fuel cell isn't going to have high speed moving components.

                    • by Amouth ( 879122 )

                      I agree it is very different, and for that reason you can't say "it should be easy to manage a solid-oxide fuel cell running at 1000C as the power source for a car because my diesel powered ICE has burns up to 1000C"

            • Maximum cycle temperatures for a diesel are shown as between 1500K and 2100K which is 1200C to 1800C

              On a theoretic basis, that is what gives a diesel such a high thermal efficiency.

              Oh grave, where is thy victory?
              Oh Carnot, where is your cycle?

              (Sorry. It's below even my normal standard, which goes down from "terrible".)

      • Neither of those sound like unsolvable problems.

        People don't like being bounced around either, so we use suspension and soft seats for them.

        The combustion chamber in a gas engine gets to around 1000 degrees C as well, and that isn't a problem. We can get rid of the heat if necessary, or if it needs to stay hot we can stick it in an insulating box. Either way, it sounds doable.

        2kW isn't enough for a car though, and if you were to scale it up to the 100kW to fulfil a cars peak demand, it might prove too bi

      • by Svartalf ( 2997 )

        Considering that you find it present in the engine all the same (cylinders...)... I think someone could manage if it were just the heat that was a problem.

        The reality is, how big are those fuel cells for 2kW of power? Your car typically does vastly MORE kW of energy output- somewhere between 25 and 367 kW of energy. And we won't even get into the mis-representation of 2kW being the average for a house...most of the larger appliances use 1-3kW apiece. (This doesn't get into the HVAC, regular or on-demand

  • by Anonymous Coward

    Hold the phone, 2kW enough for an average home? Well, i'm sorry but i have an average home but 2kW isn't enough for me. I mean, 2000W is just enough power for a small heater.

    • by AvitarX ( 172628 )

      Seriously, that's essentially one circuit.

      It's 1/2 of a dryer.

      • by AvitarX ( 172628 )

        Though, I suppose if it requires gas, the dryer is not an issue, it's still not much. certainly no AC is going to happen on that.

        It'd be doable, but it'd suck, and using central heat instead of space heaters would drive up overall energy usage for me at least.

    • Re:2 kW enough? (Score:5, Insightful)

      by newcastlejon ( 1483695 ) on Sunday June 03, 2012 @03:04PM (#40202703)
      If there's already a gas supply in place, why use electricity for heating?
      • Good point. Gas furnaces are already over 98% efficient. That is so efficient that the exhaust gas is cool enough to simply vent via a PVC pipe, and a drain is required because water condenses out of the exhaust gases.

        • Re:2 kW enough? (Score:4, Informative)

          by fa2k ( 881632 ) <pmbjornstad@g[ ] ['mai' in gap]> on Sunday June 03, 2012 @04:07PM (#40203161)

          Electricity can be more than 100 % efficient if you use a heat pump ( [] ).

          • Re:2 kW enough? (Score:5, Interesting)

            by fgouget ( 925644 ) on Sunday June 03, 2012 @05:30PM (#40203775)

            Electricity can be more than 100 % efficient if you use a heat pump ( [] ).

            You're forgetting that power plants have efficiencies of 30% or less. So add a heat pump with a typical COP of 3 and the overall cycle is no better than burning the gas directly. Now if the 50% efficiency figure quoted for this fuel cell is really just for the electricity generation side (i.e. does not take into account heat generation), then that may be more interesting. It would actually be a step up from standard power plants too so if it can be scaled up it should be.

            • How efficient is the production of natural gas and pumping it to houses?

              • by fgouget ( 925644 )

                How efficient is the production of natural gas and pumping it to houses?

                That's irrelevant since you incur the same costs whether you directly burn the gas for heating or use it in the fuel cell and then use electric heating. Now in the absolute conventional gas has an EROI somewhere between 20 [] and 100 []. I doubt distribution uses much energy but I could not find any figure so if you find any please post them.

              • Based on cost, more efficient than electric. IE compare production cost of electric ($.03 to $.08 per kwhr) to the cost at my house $.25, net cost of Ng per BTU is less than the delivery cost of electric, where I live.

          • Gas powered heat pumps can be more than 100% efficient as well. The natural gas to runs an ICE that provides mechanical power for a compressor. You recover exhaust heat and your overall exhaust is actually colder than ambient. Current efficiency's range from about 120 to 150%. A small generator can be attached to the shaft as well and provide enough power for control and to possibly operate a blower. It is a neat system, but they are not catching on.

            • by adolf ( 21054 )

              I need to buy a furnace for the upstairs portion of my house sometime in the not-distant future.

              I was considering just implementing a high-efficiency natural gas unit (since that's relatively cheap around here), but your suggestion changes things.

              Where can I learn more about such a concept?

          • by dfghjk ( 711126 )

            Heat pumps don't need to be powered by electricity.

          • by Svartalf ( 2997 )

            Ah, but it consumes ~10-20kW being more efficient.

    • Re: (Score:3, Informative)

      by JimCanuck ( 2474366 )

      Averaging it out, yes 2kW is probably typical in most homes. As gas furnaces are typical, and if you eliminate your stove, and instead use a natural gas stove, 2kW as a ceiling would be easy to maintain.

      Personally for my own uses, 2kW/h nearly excessive, due to my gas furnace, gas water heater and gas stove, I'm averaging out approximately 1.25kW to 1.5kW per hour with a ceiling of 2kW. That includes running 2 TV's, a PC I set up as a file server, 2 other PC's, 2 fridges in the home and the Microwave runn
      • by NoNonAlphaCharsHere ( 2201864 ) on Sunday June 03, 2012 @03:12PM (#40202749)
        I can just picture explaining to my wife that she has to unplug the refridgerator before she can turn on her haid dryer.
      • Re:2 kW enough? (Score:4, Informative)

        by houstonbofh ( 602064 ) on Sunday June 03, 2012 @03:41PM (#40202943)
        Unfortunately, air conditioning does not work as well off natural gas as a heater. My boat needed more than 2.5kw for the air conditioners. In Houston, most of the standby generators in case of hurricanes are 5kw to 7.5kw, and some larger houses have 15kw.
        • by Svartalf ( 2997 )

          And those are for pared down usages. 15kW works out as a good start for what is actually reality for a 1500 square feet house to ensure all things work as you're used to.

      • Re:2 kW enough? (Score:5, Informative)

        by michael_cain ( 66650 ) on Sunday June 03, 2012 @05:00PM (#40203549) Journal
        The standard numbers that are tossed around for the average US suburban home (where a bit over 50% of the population lives these days), is 30 kWh per day, with a peak hour usage as high as 6 kWh, depending on location. IIRC, the peak hour tends to occur in the late afternoon and early evening, and varies somewhat between households: people coming home from school/work and turning on lights and A/C, parents firing up the washer/dryer, electric cooking, etc. We looked at converting to NG for cooking at one point; current code requires venting to the outside, which would in turn require some structural work. A contemporary single-family house in the US suburbs will be equipped with at least the equivalent of 125-amp 120-volt service (supports 15 kWh per hour max); the equivalent of 200-amp 120-volt service (24 kWh per hour) is not unusual.

        Obligatory "Get off my lawn you damned kids!" anecdote. When my kids were in their early teens, I swear they could come through the front door and within 60 seconds, turn on 500 watts worth of assorted load each. Ever since, and after comparing notes with colleagues, I've claimed that one of the defining characteristic of dads who've had teenagers is a compulsive urge to turn things off and sit quietly in the dark.
        • Check your units. kWh per hour would be an accelerating rate of energy usage.
          • Re: (Score:2, Informative)

            by Anonymous Coward

            Haha, no. kWh/hour = kilowatt, so it's power.

          • The electricity industry insists on using these strange units of energy that are used no-where else. It's annoying.
            • by Svartalf ( 2997 )

              They're not strange. Using Joules and Ergs are strange. As for being used nowhere'd be mistaken on that score.

          • Check your units. kWh per hour would be an accelerating rate of energy usage.

            Might want to check your units too. The hour in KWh and in hour cancel, leaving KW.

          • by Svartalf ( 2997 )

            kWh is simple, really. 6 kWh is either 1 kW over 6 hours or 6 kW over 1/6 of an hour.

            The average house would be properly sustained with something between 8-15 kW continuous with some higher-end sets of efficient appliances needing up to 25 kW to keep everything out of brownout conditions within the house.

        • by godefroi ( 52421 )

          Y'know, I was just wiring my basement the other day, and while contemplating whether to run power to the light switches or to the light fixtures (either is possible), it occured to me that if I ran power to the fixtures, I couldn't install any of those fancy-schmancy computer-controlled switches. Then, I thought, hey, computer-controlled light switches. I could just set up the system to turn off every light in the house every 15 minutes, and the dang kids could just turn back on the ones they actually neede

      • Depends on your "lifestyle":

        PS3 + 50" plasma screen > 0.5kW/h

        Fancy bitcoin mining parallel GPU setup can be > 1kW/h

        4 ton A/C unit running full tilt > 2kW/h

      • 2kW average may do the job for the most part... You can argue that the heating system, stove and hot water heater should run on gas... but in the South, we like our air conditioning. 2kW won't even kick over the compressor in my home's system. I recently did the calculation for what I need, in terms of a backup generator. It was on the order of 10-12 kW to handle the peak load (HVAC startup).

      • by Svartalf ( 2997 )

        No, it wouldn't. A 1-ton HVAC might run in a 2kW profile, but it'd leave you about 500-700W of leftover before you exceed the budget and go into brownout on the unit. 2kW is a minimum power level to keep maybe a fridge/freezer going or a small, small house's low-end consumption.

        2kW working out on a house is a lie.

    • They mean AVERAGE, not maximum output. And if you have batteries in place, and transformers, and actually one little small el.central....
      • They mean AVERAGE, not maximum output. And if you have batteries in place, and transformers, and actually one little small el.central....


        "This methane-fueled cell achieves about 50% efficiency at around 2kW, enough to power an average home."

        So it is not enough to power an "average" home for peak use. And it is not enough to power an average home for average use in a very warm climate. AC uses a lot of power.

        • Re:2 kW enough? (Score:5, Interesting)

          by funwithBSD ( 245349 ) on Sunday June 03, 2012 @04:01PM (#40203109)

          I have a 2.9Kw solar, so let me explain how this works.

          My bet is that this device does not switch on and off real fast, nor does it modify it's out put much.

          And for most systems, like the solar, that produce DC, you need an AC converter. The most efficient ones take the "heartbeat" of the grid to time themselves and makes sure you are not out of sync with the grid power.

          That means while you are using .5 or 1Kw steady, you are pumping power out to the grid, running the meter backwards.

          When it comes time for a peak surge, you draw from the grid to provide the peak.

          So my solar that puts out 22 to 26KW a day during the peak months of May to September roughly half that energy goes back on the grid, I pull some back for peak usage, and pull the rest back at night.

          The GRID is my battery, and it is better than free, I get 3.2c credit for producing at peak and pulling at night.

          • by Kjella ( 173770 )

            With solar that makes sense because you're really generating the power with your solar cells, when they're first installed you're collecting free sunlight. I don't see the big point in buying a small methane generator and then buy methane while tied to the grid, then I assume it would be much cheaper to put a big methane power plant on the grid and buy electricity from there. In short, I don't see a big reason for ever turning this generator on unless you're off the grid...

        • The power output is DC. So all you need to do is stick a great big battery bank in there. Problem solved.
      • by Anonymous Coward

        They mean AVERAGE, not maximum output. And if you have batteries in place, and transformers, and actually one little small el.central....

        No. They mean peak. Average usage is measured in kilowatt hours(kWh). Generator output is an instantaneous measure of continuous or peak current output, usually kilowatts(kW).

        A gasoline powered portable generator from a large department store is typically 5kW advertised peak. In reality you'll get a constant draw of 4 to 4.5kW Take it from someone who has lived off of a 5kW generator for two weeks, post hurricane. You cannot run an entire house off of it. You can run the fridge/freezer(1.2kW), a few lights

    • by kanweg ( 771128 )

      It's 2012. Time to switch to a heat pump then.


      • by Svartalf ( 2997 )

        Heh... A heat pump may be efficient in terms of what it does for it's power consumption- but it consumes the SAME amount of power as a high-efficiency AC unit in terms of what it consumes per every ton of heat pumping capacity. Start load amps requires that you source it 10-12kW for a typical 2-4 ton HVAC system.

    • Well, once you move water heating to a solar heater or gas heater and if you live in an area without need for Air conditioning, 2kW is much more then enough
      my home uses less than 1kW after excluding AC and water heating
      • I think about 60% to 75% of my power use is AC, and I leave multiple computers on 24/7. But AC is not an option in Houston.
        • Re:2 kW enough? (Score:4, Insightful)

          by HiThere ( 15173 ) <{ten.knilhtrae} {ta} {nsxihselrahc}> on Sunday June 03, 2012 @05:57PM (#40203925)

          You may "need" air conditioning, but there are ways and ways. With decent insulation, you need a lot less air conditioning. I don't know what your understory is like, but in many places you can store heat there in summer, and withdraw it in winter (using some sort of heat pump). That's not enough on it's own, but combined with decent insulation, it get's you quite close to reasonable. Then you need only a quite small amount of either air conditioning or heating.

          That said, I'd expect that in Houston the most reasonable alternative would be solar. (And since you're in town, it's not reasonable to even try to get off the grid.)

          But the first step is GOOD insulation. With good enough insulation, you could overheat a house just by living in it, even during a blizzard, but that much is unreasonable. It does, however, imply that you'll need some air condition, and air circulation, too, but the air circulation system could go via a heat exchanger, so not too much heat transferred via that pathway.

          OTOH ... you won't see me investing in that kind of system. Yes, it would work, but it's too complex, and would probably require lots of maintenance. But with proper design, 2 KW should be plenty. It's just that proper design is quite rare. (FWIW, my wife thinks that we have good insulation. It is to laugh. The wind blows through the house, even with the doors closed. But it suffices for our environment [SF Bay]. Elsewhere I'd be much more interested in better insulation.)

          • by Svartalf ( 2997 )

            The only way you're going to get 2 kW to work well for HVAC is if you're further West than Weatherford or Austin in Texas and use a Coolerado indirect-evap cooling system. The closer you get to the Rockies and/or the Desert, the easier it is to get the same sensible cooling on only 500-1 kW. But in the more humid parts of the Country, it's just not going to work well for you without some compressor or similar refigeration cooling to get you into the comfort zone.

            I researched all of this when my AC died an

          • People in a house need to breathe. Even with perfect insulation, heating subfreezing air to room temperature takes as much energy as you generate by oxidizing food in your body to heat the air you breathe. A heat exchanger recovering the heat in air leaving the house to warm the entering air is also required.
    • by malx ( 7723 )

      2kW is an "average home"? Seriously?

      My induction cooktop has a rated load of 11kW!

      Rated loads on some other devices:
      PC power supply: 800W
      Plasma TV: 420W
      Home cinema amp: 870W
      Stereo amp: 800W

      I also have an electric oven (two actually), a washer-dryer and a dishwasher. It is by no means inconceivable that all these devices would be running simultaneously. And that's without counting the multiplicity of relatively low power devices, which will all add up.

      In common with most British people I don't have air-con.

      • My induction cooktop has a rated load of 11kW!
        Rated loads on some other devices:
        PC power supply: 800W
        Plasma TV: 420W
        Home cinema amp: 870W
        Stereo amp: 800W

        Am I so atypical?

        Honestly, that sounds like a premium setup. Not excessive, but not average. 2kW is just a starting point and will be coupled with efficiencies in consumption and supplemented by the grid for peak consumption. As another poster pointed out, if you have a supply of natural gas then a gas cooker could be part of that solution.

    • by tragedy ( 27079 )

      Presumably this would need to be coupled with a storage bank of batteries, or something like that to meet peaks of demand.

    • That's probably averaging out. 2KW averaged over a few days, but with peaks much greater when the electric shower is on or someone is drying their hair. You could use an inverter to help with that. It also can safely ignore heating and cooking, as that'd just run off burning the gas and thus use negligable electricity.
  • That should be part of the efficiency calculations as well.

    • The answer to that is: extremely expensive. And that's probably why they didn't present any of the figures. The compression, material and heating costs to remove all the CO2 from the gas would likely make the total cycle efficiency terrible.
  • by fustakrakich ( 1673220 ) on Sunday June 03, 2012 @03:01PM (#40202681) Journal

    It makes all the machinery frail and brittle. I'll settle for a few percent less with a Stirling engine running off the natural gas we have now. And most likely it will run on anything I throw into the 'boiler'.

    • If the cost of replacing or rebuilding machines is less than the cost savings in fuel efficiency, you loose.
    • by rtb61 ( 674572 )

      If you are going to stick to burning, it is smarter to go co-generation. Instead of a normal hot water service, have a small gas turbine motor running powering a generator and use the waste heat for your hot water service ie. you would only run it when you needed to heat your water but at least you getting some electricity out of the combustion process (you could even carry the principle over to stoves). The whole idea of course is to stop burning stuff, it really is a rather primitive way to generate ener

  • by Animats ( 122034 ) on Sunday June 03, 2012 @03:08PM (#40202727) Homepage

    A classic problem with fuel cells is extreme intolerance to contaminants. [] Even trace amounts of contaminants tend to damage fuel cells. Hydrogen fuel cells need cleaner hydrogen than is normally available commercially. Research continues on making fuel cells more tolerant of contaminants, but it's hard. Fuel cells are surface chemistry systems. 40 years of research hasn't solved this problem.

    Reverse osmosis water purification systems once had the same problem. Today they routinely take in raw seawater and pump out clear water. They just need a backflush cycle once in a while to flush the crud off the membranes. Fuel cells aren't there yet.

    • You have hit the mail on the head. Reverse osmosis membranes can be easily cleaned by reversing the pressure so that a small amount of fresh water will flush the built up salt. There is no such mechanism with fuel cells. When natural gas is used the impurities coat the reaction plate and decrease the reaction. There is no way to reverse the process to clean the plates. It is very difficult to create perfectly clean natural gas. Even a small amount of impurities will coat the plates creating an insulation la

    • by orzetto ( 545509 )

      A classic problem with fuel cells is extreme intolerance to contaminants. Even trace amounts of contaminants tend to damage fuel cells.

      The article you link is about PEM fuel cells, which are indeed sensitive to contaminants (though not "extremely", i.e. they don't die the moment one CO molecule comes around). TFA is about solid oxide fuel cells, which are not particularly sensitive to pollutants (some have been made that run on carbon monoxide).

      Hydrogen fuel cells need cleaner hydrogen than is normally avai

  • Until now, the most efficient electric generators for home use I've seen are heat-power coupling devices: natural gas-powered engines that have their coolant loop linked to the house central heating system. They can reach a combined efficiency of near 100%, if you can use the heating. In the summer, they get expensive to use.
    60% efficiency for electricity alone is pretty good.

  • by Skapare ( 16644 ) on Sunday June 03, 2012 @03:15PM (#40202769) Homepage

    I already have a home source of methane. I just need a nice way to capture it.

  • Make it run reliably for 2+ years and you got a market. 2KW is small for Canada as if you pull 1lb out of a 100W light thats only about 2K every 8 weeks. Now in the US you're looking at 3000-4000K for that same lb.

  • what about building them at sub stations?

  • How effective would methane generators be in small farming communities, which already produce methane as a by-product? If they work well, then they may be able to be off-grid completely?

    • Impractical at present. Fuel cells require extremely high purity methane and the equipment to purify random natural gas or decomposition gas is expensive.

      Just burning the stuff in an ordinary generator is way better in terms of return on investment.

  • Bullshit
    Or pig shit.

    Keep livestock,
    gather the manure,
    make methane.

    In our case though the animals spread the manure out in the fields which is far more efficient.

  • Houses Need 5KW (Score:4, Informative)

    by Doc Ruby ( 173196 ) on Sunday June 03, 2012 @04:49PM (#40203477) Homepage Journal

    The average American house consumes about 1.5KW electricity average across the days (and nights) through the weeks of a year. But they not infrequently peak demand in spikes over 2KW. A hairdryer or space heater draws about 1.5KW. A dishwasher (especially with extra washing or drying heat boost) will draw 1.5KW. An electric stove/oven can draw 4KW or even 7KW as it heats up. A vacuum cleaner can draw up to 1.5KW, especially if it's a strong one that gets jammed.

    And all of those could happen at once. A couple happening at once is pretty likely at least once a year. Plus the rest of the 1KW regular demand, which is closer to 2KW max, averaged against quiet times closer to 0.1KW.

    A home power supply should be close to half the 100A 120VAC panel, which is 6KW. A 5KW max supply is probably just fine. A 2KW fuelcell would need a battery that can output 5KW for at least a few minutes, perhaps while an alarm goes off warning the battery will drain down shortly and circuit breakers will snap.

    Really all the residential fuelcells I've seen talked about are 5KW. A 2KW fuelcell seems like a good device for a yacht.

  • The image I have of the US does not include 2KW covering the average home. It might do for the 96% of the planet outside the USA though...
    • That's 2KW averaged throughout the day, including the ~1/3rd of the day when everyone is asleep.

      You'd need a sizable capacitor or battery to handle peaking.

  • This could evolve to underwear that powers your phone!
  • 2 kW is plenty to cover the AVERAGE energy use, but not enough to cover peaks for many if not most homes. If any of: stove, clothes drier, water heater are electric, it would fall flat on its face if one or some combination of those, plus maybe a toaster, microwave, or hair drier, just happened to be running at the same time. And that's not even counting electric primary or supplemental heat.

    Hint: all of those are 0.5-1+ kW apiece. An electric oven alone is 2kW. Maybe that's why 8-12 kW is the normal provis

  • There's a fairly new commercial product called BlueGEN [] which connects to a domestic natural gas supply; I think they're marketed more toward light industrial use, but if the price comes down (currently ~ $45K Australian) it could be an excellent distributed electricity generation option.

  • Who knew? Isn't methane regularly burned off at oil refineries? Never quite understood wasting it. Same could be said of dairy farms and cattle feed lots although it probably would cost a lot to harvest it out of the air.

Today is a good day for information-gathering. Read someone else's mail file.