[HN Gopher] Why have I never heard of the Ene-Farm? (2017)
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Why have I never heard of the Ene-Farm? (2017)
Author : xhrpost
Score : 49 points
Date : 2022-09-02 19:09 UTC (3 hours ago)
(HTM) web link (earthbound.report)
(TXT) w3m dump (earthbound.report)
| Animats wrote:
| Panasonic still has some product info.[1]
|
| Natural gas powered fuel cells are available from some gas
| companies.[2]
|
| Problems seem to be:
|
| * Runs at very high temperatures, around 1000C, which means
| materials problems. Also, high grade heat is nice, but not that
| useful for home applications. So actual sales of this technology
| are to businesses.
|
| * There's been recent work on catalysts to bring the needed
| temperature down to 500C or so.[3] That's easily managed; auto
| engines run that hot. The catalyst needs ruthenium, which is
| expensive, although cheaper than platinum.
|
| * Sulfur in natural gas messes up the process, although this can
| be overcome. General problem with fuel cells: they need clean
| input gases.
|
| * Apparently you get a lot of heat and a little electricity. This
| limits the usefulness. The gas company in the US which sells this
| services Maine and Vermont.
|
| A nice application for this would be a little unit to provide
| backup power for natural gas furnaces, so you could run the fans
| without external power.
|
| [1]
| https://www.panasonic.com/uk/corporate/sustainability/produc...
|
| [2]
| https://www.eversource.com/content/ct-c/business/services/co...
|
| [3]
| https://www.sciencedaily.com/releases/2018/10/181029130939.h...
| api wrote:
| I've always been surprised that nobody has done home cogeneration
| for heat and hot water. Seems like an absolute no-brainer way to
| get a lot more mileage out of gas.
| KiranRao0 wrote:
| In Iceland, they cogenerate hot water and power due to the
| abundance of geothermal. Not exactly a common case that's
| replicable everywhere, but mildly interesting.
| Jtsummers wrote:
| You can get boilers that generate steam for radiators and hot
| water for tap water.
| yetanotherloser wrote:
| Genuine, this-never-occurred-to-me question: are there lots
| of people out there with boilers that DON'T do this, or areas
| where it is not normal?
|
| If so - this might explain something that's been mildly
| irritating me. When looking for alternatives to fuel-burning
| boilers it seems easy to find positive stories about space
| heating - and much less info on water heating, to the point
| where it's starting to look like maybe some of these options
| might not be great. Water heating is my largest home energy
| usage and space heating very little because it is grossly
| overrated; if you are not really unwell an indoor temperature
| around 10 c is quite pleasant, so I tore my (rubbish)
| radiators out in 2017 and never looked back. This is making
| it surprisingly hard to figure out what replaces the boiler.
| If the marketing is aimed at pure heating boiler replacers,
| this difficulty is at least easier understood if not easier
| solved.
| projektfu wrote:
| Heat-pump water heater:
| https://www.ecohome.net/guides/2197/heat-pump-water-
| heater-w...
|
| I would personally not like to live in 10degC but I prefer
| hot climates. 15degC I could do. How do you keep the
| temperature above 10degC? Or is the outside temp rarely
| below 10degC?
| yetanotherloser wrote:
| Thanks! that looks technically similar to the heat pumps
| aimed at space heating but a bit better - perhaps there's
| an efficiency in it being meant to do just one job? It
| looks like it (or its ilk) might be a good fit for me.
|
| Outside wobbles around -2 to 8 in winter here, inside
| rarely less than 6, which is nippy but not dangerous. A
| not very insulated house with solid walls (this one's
| from about 1890 and has only had the easy things done)
| doesn't really sink to outside temperature if you live in
| it, cook, have appliances etc. There are plenty of heat
| inputs, just they do another job first. Hence my interest
| in water heat, I think it would start to be grim without
| it. Stove for a small number of really cold evenings,
| plus visitors. It would be a really bad idea to use it
| all the time but it would be hard to fit a radiator-type
| system to the job of "one hot room occasionally".
| wffurr wrote:
| I read about a Mitsubishi home gas cogeneration system many
| years ago (10 ish). I think they haven't taken off because they
| are expensive, only suitable in certain climates, and
| significantly less efficient at producing electricity from gas
| than a recent model combined cycle gas power plant.
| bdcravens wrote:
| So it's basically a Generac? I know that those are mostly for
| backup, but my understanding that they are perfectly viable for
| longer term use. (though they would need occasional maintenance)
| NovemberWhiskey wrote:
| If you mean "is this a reciprocating piston engine with a
| generator that's plumbed for natural gas?" then no ... this is
| fuel-cell technology, not internal combustion.
| arcticbull wrote:
| > The most important is that the electricity is generated on
| site, so there are no losses in transmission.
|
| People really overestimate transmission losses. They averaged
| only 5% in the US between 2016 and 2020. [1]
|
| I believe if you wanted to run a power line from Boston to LA
| you'd only lose about 25%.
|
| [1] https://www.eia.gov/tools/faqs/faq.php?id=105&t=3
| pavon wrote:
| In addition, generating electricity in a large power plant is
| significantly more efficient than doing so on a small scale
| even after taking transmission loss into account.
|
| It looks like the primary advantage of a device like this is
| that you can make use of heat that would otherwise be waste.
| [deleted]
| digdugdirk wrote:
| Interesting. It claims "95% combined heat and electrical
| efficiency". I'm assuming this number is comparing immediately
| after the electrical generation occurs (i.e. - this doesn't have
| any transmission losses, while the electrical grid does).
|
| Does anyone have any comments on the comparison in overall gas ->
| electrical output efficiency between large grid-scale natural gas
| plants and small natural gas generators like this one?
| smartmic wrote:
| Wikipedia has some reasonable figures about Cogeneration fuel
| cells (Ene-Farm is one of those "MicroCHP" fuel cell systems
| for home usage[1]:
|
| > Co-generation systems can reach 85% efficiency (40-60%
| electric and the remainder as thermal).[5] Phosphoric-acid fuel
| cells (PAFC) comprise the largest segment of existing CHP
| products worldwide and can provide combined efficiencies close
| to 90%
|
| For the "95% [...] efficiency", I guess they take the hydrogen
| heat input for calculation of efficiency. What I miss are the
| losses from conversion of natural gas to hydrogen. This has to
| be considered when comparing efficienies eg. with gas fired
| power plants.
|
| So when it comes to large-scale Combined Heat and Power plants
| [2], it depends. There are not only different types of power
| plants (coal fired, gas fired, etc.) but also the heating part
| varies (process steam, district heating, etc.). If you go
| thermodynamically strict, you would also have to consider the
| quality of heat (at which pressure & temperature level is the
| heat extracted). This is normally not considered in the
| standard efficiency formula.
|
| [1]
| https://en.wikipedia.org/wiki/Fuel_cell#Efficiency_of_leadin...
| [2] https://en.wikipedia.org/wiki/Cogeneration
| i_am_proteus wrote:
| I suppose there's some ambiguity in the wording... there's no
| way it's 95% electrical generation efficiency.
|
| The key is that waste heat from electrical generation is used
| to heat an otherwise-cold home, and perhaps the hot water.
|
| That efficiency isn't going to be possible when it's warm
| outside.
| jsmith45 wrote:
| Gas power plants on the grid are pretty inefficient. Like a
| modern furnace they are pretty efficent at getting the heat
| energy out of the gas. However the efficiency of turning the
| heat into electricity is low. They get something like an
| average of 40% overall efficiency. The best gas turbine plants
| on the market can get about 60% efficiency max.
|
| If the power plants were able to provide the excess heat to
| nearby businesses and the like, they could be a lot more
| efficient overall, and there are some that have tried to do
| that, but transporting heat itself is not an easy thing to do
| efficiently, and many plants are things like peaker plants,
| which don't run consistently, making it even harder to sensibly
| use the "waste" heat in the nearby communities.
|
| Then there is the grid losses. Grid transmission loses 5 to 6%
| of the power in the US, making the grid 94-95% efficent.
| cogman10 wrote:
| Combining heat + electrical energy makes the stats really
| muddy.
|
| Does 10% of the burned energy end up as electricity? Or is it
| more like 30%? Hard to tell.
|
| The real question is, what do you do with that heat when you
| don't want it? What's the efficiency then?
|
| I will say, it would be pretty neat if one day we could get a
| mutli-device heat pump system going. Wouldn't it be cool if the
| heat pulled from your home was dumped into the water heater
| before being extracted vented? Or if instead of your fridge
| having a heat pump, it simply tied into a home heat pump
| system?
|
| This sort of thing would call for a centralized compressed
| lines. And, perhaps the reason that's not happened is because
| we don't want to worry about what happens when toxic gasses
| discharge into the home.
|
| Still, would be pretty neat if we could have a centralized cold
| and hot compressed gas system for buildings.
| aftbit wrote:
| Commercial and larger residential buildings often have water
| at various temperatures as a utility. There will be a machine
| room that has large water-to-water heat pumps, then a chiller
| tower on the roof that takes hot water, evaporates some and
| cools the rest, then returns it to the hot-side heat
| exchanger. The cold side will circulate water around the
| building, where it will be used in water-to-air heat
| exchangers on the room or unit level to cool the building. In
| most climates, larger buildings need more cooling than heat,
| but doing the same thing with a hot water system is quite
| common as well.
| mikewarot wrote:
| You could use this to power AND heat the cold side of a heat
| pump, possibly getting far more than the original heat output of
| the gas into a building in a cold climate that would normally be
| too cold for a heat pump.
| stevehawk wrote:
| I'm not smart enough to know what's going on here. This is using
| solar power to help make hydrogen which is then using the
| hydrogen to create electricity? And then because of the heat
| generated it can also be used to heat a structure (to some
| degree)?
| aaron695 wrote:
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