[HN Gopher] Heat your house with a mechanical windmill
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Heat your house with a mechanical windmill
Author : solalf
Score : 103 points
Date : 2023-08-20 18:23 UTC (4 hours ago)
(HTM) web link (solar.lowtechmagazine.com)
(TXT) w3m dump (solar.lowtechmagazine.com)
| realusername wrote:
| > The Calorius type 37 - which had a rotor diameter of 5 meters
| and a height of 9 meters - produced 3.5 kilowatt of heat at a
| wind speed of 11 m/s (a strong breeze, Beaufort 6). This is
| comparable to the heat output of the smallest electric boilers
| for space heating
|
| Well, there you have it of why it's a relatively unknown tech
| (that I also didn't know about). The heat produced is very small
| for a house yet the blade still needs to be very high, making it
| impractical on most houses. On top of that hot water transport on
| long distances is a recent thing due to advancement of pipe tech
| which made communal version of those impossible at the time.
| usrusr wrote:
| Wind is just not good at all scaling down, no clever trick on
| the every use side or I the side of blade geometry will ever
| change that.
| seeknotfind wrote:
| Essentially, it's more efficient to generate heat directly from a
| windmill, than first turning it into electricity.
|
| That being said, porque no los dose. Efficient heat is great, but
| you don't always need it. If you only use the electric generator
| a few months a year, it may still be worth it, given you're
| investing in a windmill.
| bryanlarsen wrote:
| Given that a heat pump can be a lot more than 100% efficient,
| it's likely more efficient to generate electricity and then use
| a heat pump to heat the house.
| [deleted]
| fancyfredbot wrote:
| The article has a long section on using the windmill to
| directly drive the compressor of a heat pump using a gearbox.
| This is likely to be more efficient than converting to
| electricity and then using that to run an electric
| compressor.
| toast0 wrote:
| There's no reason you couldn't run the compressor of a heat
| pump mechanically. Then the question becomes is it more
| efficient to generate electricity to run a motor (or a linear
| compressor, I suppose), or use a gearbox to change the
| rotation speed. Plus or minus if you need mechanical air
| movement in the conditioned space.
| bluGill wrote:
| The reason you don't want to do that is you need to store
| the energy for times when the wind isn't blowing.
| TeMPOraL wrote:
| Energy storage doesn't require going through electricity
| either; in fact, highest capacity storage systems are
| mechanical - flywheels, lifting heavy objects high, or
| pumping water up the hill.
| LgWoodenBadger wrote:
| Mechanical heat pumps are covered in the article. And for
| the child response to yours, mechanisms for sourcing heat
| for longer periods are also covered (e.g. 10k, 20k liter
| tanks of warm water, hydraulic oil vs water as primary heat
| transfer fluid)
| detourdog wrote:
| If one has a solar install already creating a diverse sources
| of heat makes sense in the northern climates.
| juujian wrote:
| For a lot of folks in the Northern hemisphere, heating is the
| largest share of domestic electricity consumption. Same for
| offices. I would say there is great potential for this to
| reduce electricity consumption, plus the hot water can be
| stored without the loss at conversion that electricity has.
| Rygian wrote:
| The spelling that a Spaniard would consider correct is "?por
| que no los dos?" and it would still be acceptable as "por que
| no los dos?"
| tedunangst wrote:
| People posting porque on English forums are not trying to
| communicate with Spaniards.
| mschuster91 wrote:
| > Renewable energy production is almost entirely aimed at the
| generation of electricity. However, we use more energy in the
| form of heat, which solar panels and wind turbines can produce
| only indirectly and relatively inefficiently. A solar thermal
| collector skips the conversion to electricity and supplies
| renewable thermal energy in a direct and more efficient way.
|
| Ooof. What? The first paragraph and it's just utter bollocks.
| Combine a solar panel or a wind turbine with a heat pump and
| despite generation losses it will outperform _any_ thermal
| collectors - there 's a reason these got virtually phased out!
|
| And on top of that: local windmills, that may work out on farms
| in backwater rural towns with no grid worth calling it that, but
| good luck getting a permit for windmills in anywhere else, and
| when there's no wind you're straight out of luck whereas an
| electric heat pump can always be powered from the grid, or in the
| case of a massive power outage, from an on-site backup generator.
| aziaziazi wrote:
| > Combine a solar panel or a wind turbine with a heat pump
|
| Two studies did that and mechanical heat pumps win. Here's the
| links from the blog post:
|
| https://elib.dlr.de/103317/1/20160224%20-%20Master%20Thesis_...
|
| https://www.sciencedirect.com/science/article/pii/S096014811...
| mlyle wrote:
| You're talking past each other.
|
| He responded to a statement in the article comparing solar
| thermal collection with solar + heat pump.
|
| The article mostly talks about mechanical heat pumps, and you
| leapt to that, talking past him.
|
| (I think both the article and him are not strictly correct:
| solar thermal heating has a place but is not typically a
| efficiency win).
| ForHackernews wrote:
| > but good luck getting a permit for windmills in anywhere else
|
| Just because silly bureaucracy exists doesn't mean something is
| a bad idea.
| IshKebab wrote:
| For wind sure, but is that true for solar? Solar panels are max
| 20% efficient and head pumps typically have a COP of 2-3, so
| solar thermal only has to have an efficiency of around 50%. 1
| second googling tells me it is 70%.
|
| I think the real reason nobody does solar thermal is because
| it's just so much less practical to deal with pipes and pumps
| and heat reservoirs than wires and batteries. Also it is
| useless in the summer when you don't need heating.
|
| Wind is always going to be niche for most people for obvious
| reasons.
| veb wrote:
| I have seen these turbines within city limits (in NZ):
| https://www.powerhousewind.co.nz/thinair-wind-turbine/
| apparently they make a lot less noise. I'm sure some
| intelligent people will keep iterating on these technologies.
|
| They do an awesome solar+wind deal too:
| https://www.powerhousewind.co.nz/powercrate/
| atoav wrote:
| Having a black water tank on the roof for solar heated warm
| water is not uncommon in southern Europe.
|
| Most camping showers work by the same principle. If you need
| warm water and you have enough sunlight to warm it when you
| need it, this is not a bad idea
| beebeepka wrote:
| > I think the real reason nobody does solar thermal is...
|
| You have a weird definition of nobody. They are not as
| popular these days but do exist and are very useful. Don't
| even that much sun to produce warm water
| mschuster91 wrote:
| > 1 second googling tells me it is 70%.
|
| ... at full sun visibility, that is. However, in winter where
| it's cloudy, raining or, worse, there's snowpack on the
| panel? Now it's at 0%, right when you actually need it the
| most.
|
| So you have to have the solar heating system and a fallback
| for winter/night, and the headaches of all that extra
| pipework just don't make it worth the effort because all
| you're going to get from it is a few hot showers during
| summer.
| Retric wrote:
| Solar thermal still works with clouds and under light snow,
| you might be thinking of concentrated solar but that's a
| different story.
|
| Also, storing a few hundred kWh of heat in a hot water tank
| is vastly cheaper than batteries. The real advantage of
| solar thermal is it can scale so well, thus allowing the
| benefit of a heated pool and later driveway without extreme
| expense. An expanded mindset around heat being so cheap
| means you can do things like warm an exterior patio for
| chilly fall days etc etc.
| falsaberN1 wrote:
| Being from a ridiculously rainy region and having worked on
| solar thermal, I can warrant you that while it's not as
| functional when in bad conditions, it still works.
|
| Consider it's usually set as a setup combined with a
| standard heating system (gas, electric...), and while there
| are situations where it can't handle the full load
| (absolutely horrible darker than night days) it'll always
| reduce or nullify costs. And since installation and
| maintenance are relatively cheap, it's always going to save
| you some money on the long run.
|
| Also consider some areas can be really hot, but have very
| cold water lines. I need to heat my water in summer despite
| being above 40oC outside. Having solar negates that cost
| entirely, giving you like 9 months where you spend nothing
| in water heating. Considering how expensive gas/electric
| has become in this country, it's quite the relief for a
| wallet.
| falsaberN1 wrote:
| I worked on solar thermal for a while. It was even mandatory
| to install in new buildings in my country for a while (before
| all solar was forbidden for personal use until recently,
| don't ask, I hated it too. Forced me to become a sysadmin
| though, which was a good move).
|
| You can get pretty good efficiency with solar thermal panels
| and indeed they are more near the 70% mark. Just a "black
| paint" panel can get "decent" results and it's relatively
| cheap. I remember back in the training days, our teacher just
| held a metal pane, painted black, into the sun for a
| demonstration. And got to 80oC in a few minutes. In January.
|
| They are not so useless in summer depending on where you
| live. In my region, despite being tropical-tier hot, water
| comes out really cold from the urban lines, so you always
| need to use some gas for a heater (butane or city gas).
| Having a solar thermal setup completely nullifies that
| (admittedly not large, but existing) expense during summer
| and reduces it during winter. Since many buildings here
| already have it as a feature, it's a little expense reduction
| which is always welcomed.
|
| I miss working on that field.
| rescbr wrote:
| > I think the real reason nobody does solar thermal is
| because it's just so much less practical to deal with pipes
| and pumps and heat reservoirs than wires and batteries.
|
| It very much depends where one is located. My parents' house,
| in a subtropical climate region, has had solar thermal for
| over 2 decades. Now they've also installed PV panels, but hot
| water is still mainly solar thermal with electrical heating
| as supplement.
|
| New houses also have dual setups like theirs. Solar thermal
| collectors for hot water + PV for other electric usage and
| selling the excess to the grid.
|
| > Also it is useless in the summer when you don't need
| heating.
|
| You still do need some water heating in the summer.
| littlestymaar wrote:
| > there's a reason these got virtually phased out!
|
| Citation needed. In my country they sell very well nowadays so
| they don't look as they've been phased out at all. And for good
| reason IMHO: they are much more rustic than heat pumps and are
| likely going to live for much longer than the later with
| cheaper maintenance.
|
| Also, as heat can be stored pretty efficiently (and cheaply)
| compared to electricity, the day/night intermittency isn't so
| big of a deal.
| jfim wrote:
| That's pretty fascinating. I was looking at off grid setups in
| Canada, but the issue there is that peak energy usage is during
| winter, which is also the time of the year with the lowest
| illumination and snow on solar panels. Having the ability to
| generate heat that way would keep the more scarce electricity for
| other uses that cannot use heat or mechanical energy as inputs.
| AS37 wrote:
| Interestingly, winter has the highest windspeed of all seasons,
| summer the lowest.
| morepork wrote:
| Depends where you live, for us it tends to be more cold and
| still in winter, but the warmer months are windier
| ZeroGravitas wrote:
| I always enjoy the articles on this site.
|
| I'd enjoy them a bit more if they didn't continually insinuate
| stuff about modern renewables that they clearly know not to be
| true due to the way they phrase it.
|
| If people leave your article with misconceptions about modern
| renewables then that is a bad thing.
| MengerSponge wrote:
| Lovely, but heat pumps can easily top 300% efficiency. If your
| electrical generation and transport is ~50% (which seems
| shockingly bad), you get a _lot_ more heating from a heat pump
| than from direct mechanical heating.
| fancyfredbot wrote:
| The article has a long section on using the windmill to
| directly drive the compressor of a heat pump using a gearbox.
| This is likely to be more efficient than converting to
| electricity and then using that to run an electric compressor.
| thfuran wrote:
| Wouldn't 50% be outlandishly good for solar? I think even 25%
| would be exceptional.
| mechagodzilla wrote:
| Electricity from solar panels on your roof is in the range of
| 16-23% efficient, but there are no distribution losses.
| Electricity from a coal plant or single-cycle natural gas plant
| is ~30-40% efficient, and a combined-cycle natural gas plant
| can reach up to 60% efficiency under ideal conditions, with an
| additional 5% of produced electricity lost in distribution.
| reliablereason wrote:
| Seams more useful to generate electricity and use the waste heat
| that comes out of the inefficiency of the electricity generation.
|
| Electricity is a far more useful energy type.
| nottorp wrote:
| For one this article is wonderfully out of season <wipes
| sweat>.
|
| If you generated electricity you'd be able to also use it for
| cooling.
|
| For two... how much land do you need to have for a 8 meter
| windmill and a reservoir with 20 tons of water? Looks out of
| the question even with detached house suburbs.
| _Microft wrote:
| Especially when combined with a heatpump that can move a
| multiple of the input energy as heat.
| was_a_dev wrote:
| Driving a heat pump mechanically with a microhydro system would
| be interesting.
|
| More consistent energy output paired with easy storage.
| Gys wrote:
| No idea how I can see the contents of this article. I see the
| title and a big yellowish area below for comments and signing up.
| Maybe because I use Firefox?
| drcongo wrote:
| Working in Firefox here, though I am using NextDNS for blocking
| a lot of annoyances and trackers.
| drcongo wrote:
| Readers in the UK might like to know you will almost certainly
| need planning permission to put one of those in your garden, and
| your neighbours will probably never speak to you again. The
| latter could be seen as a benefit for some.
| brightlancer wrote:
| Most incorporated places in the US (city, town, village, etc)
| will require permission from the local government to put up a
| windmill/ wind turbine; even when it's not required, local
| governments find ways to punish legal behavior they don't like.
|
| In rural and unincorporated areas in the US, folks would likely
| be OK.
| [deleted]
| SoftTalker wrote:
| Where I live, there isn't a lot of wind on cold winter nights.
| The air tends to be very still in fact. I would not want to rely
| on wind for my heat.
| actionfromafar wrote:
| A large tank, like the huge ones for heating oil in some old
| houses, would probably go a long way.
| bbojan wrote:
| Or generate electricity to run a heat pump for 2 to 3 times more
| heat generated than what you get from frictional heating form a
| windmill.
| aziaziazi wrote:
| This method has the drawback to loose energy (with heat!) to
| convert motion (windmill) to electricity, and then electricity
| back to motion (heat pump stator). This post talks about the
| idea of _mechanical heat pumps_ to avoid those losses and cite
| two papers that back his claims.
|
| We shall not be blind on the many avantages of electricity but
| on a pure efficiency scale converting motion to heat is a
| better idea than motion to (electricity and heat) to (motion
| and heat) to heat.
| _Microft wrote:
| How (im)practical would it be to directly drive the compressor of
| a heatpump by a source of mechanical energy?
|
| For some reason I am almost expecting jacquesm to show up with
| some first-hand knowledge ;)
|
| Edit: there is a section on this the end of the article.
| userbinator wrote:
| You'd need a system with an open-drive compressor (like
| automotive A/C or very early fridges), and a rather high gear
| increasion, but it's certainly possible. Imagine something like
| this with the motor replaced by the windmill:
|
| https://www.youtube.com/watch?v=ViO3Xky3nYE
| thsksbd wrote:
| Boiling water through friction requires seals [1] , and rubber
| seals are pretty hard (not impossible) to make low tech.
|
| The lowest tech solution IMHO is a squirrel cage generator and
| ohmic resistors. No magnets or fancy electronics are needed. Just
| remnant magnetization of soft iron and some copper wire/tube.
|
| [1] a demo doesn't need seals, but a heating solution that will
| work for ten years will.
| aziaziazi wrote:
| > seals
|
| Are they also required bellow boiling temp ? You probably don't
| need much more than 55C at home. Increase the temp to store
| more energy and use a thermal expending socket to stop heat
| production before boiling temp.
|
| > ohmic resistors
|
| Isn't it similar to the eddy current generator he talk about ?
| http://www.bulipi-eee.tuiasi.ro/archive/2013/fasc.4/p12_f4_2...
| lostlogin wrote:
| So many neat articles on that site - the obsolete section is
| particularly great.
|
| https://solar.lowtechmagazine.com/obsolete-technology/
| jv0010 wrote:
| well while we are on the topic of heating i am still surprised
| 'data furnaces' have not been adopted more.
|
| https://en.wikipedia.org/wiki/Data_furnace
| FriedPickles wrote:
| Very cool. I wonder if there's an even simpler geometry that
| chokes the flow of the air and uses the heat at the construction.
| May need to be very large, but it could be an architectural
| thing.
| borh375 wrote:
| > windmill can not only provide mechanical energy, but also
| thermal energy. The problem is that almost nobody knows this.
|
| It can also provide A/C to cool a house then. The problem is that
| almost nobody knows this, except Einstein of course
| https://en.m.wikipedia.org/wiki/Einstein_refrigerator
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