Heat your house with a mechanical windmill (2019)

https://solar.lowtechmagazine.com/2019/02/heat-your-house-with-a-mechanical-windmill/

by solalf • 3 years ago

221 131 3 years ago

solar.lowtechmagazine.com

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.

Rygian• 3 years ago

The spelling that a Spaniard would consider correct is "¿por qué no los dos?" and it would still be acceptable as "por qué no los dos?"

tedunangst• 3 years ago

People posting porque on English forums are not trying to communicate with Spaniards.

bryanlarsen• 3 years ago

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.

toast0• 3 years ago

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.

detourdog• 3 years ago

If one has a solar install already creating a diverse sources of heat makes sense in the northern climates.

fancyfredbot2• 3 years ago

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.

juujian• 3 years ago

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.

Gys• 3 years ago

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?

drcongo2• 3 years ago

Working in Firefox here, though I am using NextDNS for blocking a lot of annoyances and trackers.

truculent• 3 years ago

No issues with Firefox for me. Perhaps an extension is causing some issues?

drcongo2• 3 years ago

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• 3 years ago

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.

blitzar• 3 years ago

your neighbours will probably never speak to you again

I am ordering one right now.

lostlogin• 3 years ago

So many neat articles on that site - the obsolete section is particularly great.

https://solar.lowtechmagazine.com/obsolete-technology/

FriedPickles• 3 years ago

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.

realusername• 3 years ago

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• 3 years ago

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.

jnsaff2• 3 years ago

Exactly this. In my local home energy generation group there are a lot of people thinking they are smart by getting wind generators from alibaba and then selling them because it’s really hard to get anything usable out of them.

Someone working in the field told that anything below mast height of 30m is going to a toy at best.

jfim• 3 years ago

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• 3 years ago

Interestingly, winter has the highest windspeed of all seasons, summer the lowest.

morepork• 3 years ago

Depends where you live, for us it tends to be more cold and still in winter, but the warmer months are windier

ZeroGravitas• 3 years ago

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.

MengerSponge4• 3 years ago

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.

thfuran• 3 years ago

Wouldn't 50% be outlandishly good for solar? I think even 25% would be exceptional.

MengerSponge4• 3 years ago

Yes, but this isn't solar. And to be a like-for-like comparison, we'd have to incorporate the lost/missed energy in the windmill's vanes.

mechagodzilla• 3 years ago

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.

MengerSponge4• 3 years ago

Yes, and wind turbines are 20% to 40% efficient at converting wind into energy

fancyfredbot2• 3 years ago

MengerSponge4• 3 years ago

I know, I saw that. The article is lovely, and I love the design (dithered images like that hits all the right nostalgia notes), but it's lacking in a meaningful technical analysis.

Directly driving the heat pump has the potential to be more efficient still, but it's 1) very hard to design and 2) a custom (and therefore quite expensive) design.

Hooking your turbine to a generator, which can probably do something like 80% efficient transformation of the mechanical energy to electric energy (incorporating losses). Wire that generator to an electric heat pump.

240-320% > 100%

You can lose another half of your electrical energy in transport and storage and still come out ahead. Thermodynamics is weird.

reliablereason• 3 years ago

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• 3 years ago

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.

_Microft2• 3 years ago

Especially when combined with a heatpump that can move a multiple of the input energy as heat.

_Microft2• 3 years ago

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• 3 years ago

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

mr_toad• 3 years ago

Aren’t the air conditioning units in cars usually belt driven?

I can imagine some post-apocalyptic scavenger rigging up an air-conditioning using using a windmill and car parts.

mschuster912• 3 years ago

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.

IshKebab• 3 years ago

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.

atoav2• 3 years ago

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

mschuster912• 3 years ago

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.

rescbr• 3 years ago

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.

beebeepka• 3 years ago

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

falsaberN12• 3 years ago

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.

veb• 3 years ago

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/

landemva• 3 years ago

A friend is thinking of remodel and add solar thermal to heat basement, garage in-floor heat, and another loop for driveway snow melt. The place is well above a mile high. At first thought, it seems very practical during remodeling.

melenaboija• 3 years ago

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.

I am not sure this is true for all use cases and locations. In Spain it is mandatory since 2006 to install solar thermal panels in new buildings [1], it simply preheats water, in this case this seems way simpler than any electrical installation and you already have an energy gain. Hot water is used all year round and Spain has a good amount of sunny days.

[1] https://www.nbcnews.com/id/wbna15698812

pmontra• 3 years ago

A long 1" black pipe on the roof can provide plenty of hot water in summer for showers.

By the way, pipes are one of those things that are both metric and imperial in metric countries. We have two different series of pipes here in Italy, one with 1/2, 5/8, 1, 1 1/4 inches and one in millimeters. Gardening leans toward inches and those sturdy black plastic pipes are at least 1".

aziaziazi5• 3 years ago

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...

mlyle2• 3 years ago

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• 3 years ago

but good luck getting a permit for windmills in anywhere else

Just because silly bureaucracy exists doesn't mean something is a bad idea.

littlestymaar4• 3 years ago

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.

BostonEnginerd• 3 years ago

Heat pumps are somewhat limited in the heat they can provide. For example, it would be difficult for a heat pump to produce several hundred degrees C temperatures for an industrial process.

For applications in their wheelhouse, though, they are absolutely amazing.

stephen_g• 3 years ago

There's plenty of research going into very high-temperature heat pumps. It's likely that eventually that will absolutely be 'in their wheelhouse'. Sure, the COP might only ever be something like 2-3 instead of lower temperature heat pumps (under 80 or so °C) that can be > 4 COP but still should be more than 1...

Jiocus• 3 years ago

The article brings this up towards the end,

"These [eddy current heaters/induction heaters] are comprised of a magnet mounted on a rotating shaft, and can reach temperatures of up to 600 degrees Celsius. Using eddy current heaters, windmills could provide direct heat at higher temperatures, making their potential use in industry even larger."

whatshisface• 3 years ago

There are a couple physical principles that work together to limit solar thermal collectors: heat flows from hot to cold, and mirrors and lenses work both ways. Together, they imply that a solar collector can't heat up anything hotter than the surface of the sun because if the target was hotter than the sun, it would heat the sun up and not the other way around. The surface of the sun is 5.7 thousand Kelvin. This is enough to melt, but not boil tungsten, which I must imagine is a major issue for the tungsten gas industry.

bialpio• 3 years ago

OTOH, I can probably whip up a small windmill using the scrap wood I have laying around under my carport. I'll need to buy some parts for mechanisms / power transmission though...

mistercow• 3 years ago

I wonder how difficult it would be to engineer a direct wind powered heat pump. Theoretically, you could just mechanically drive the compressor and fans, and skip electricity generation.

(To be clear, I'm sure this would not make sense economically, but it would be really cool.)

dsr_• 3 years ago

If you have really steady winds, sure. Otherwise you're probably going to need to smooth out the RPM with an intermediate stage like a flywheel.

oceanplexian• 3 years ago

Actually you don’t even need a mechanical compressor. If you know how a propane fridge works, they boil an Ammonia mixture until it becomes a gas, it‘s condensed back into a liquid, and voila, refrigeration.

With the right materials you could use thermal solar panels to build a silent air conditioner just as easily as a heater with no moving parts, in theory. Here's an old video on the principles behind it (https://www.youtube.com/watch?v=KDPgGDCdAo4).

Xylakant• 3 years ago

For a winning combination, you can use combined thermal/solar panels and then drive a heat pump with the electricity on the pre-warmed water. But that adds complexity. The primary reason we use electricity as intermediary is that it’s comparatively easy to transport even for longer distances and can be used to drive almost any that needs energy - produce heat, cold, mechanical work, computers, …

runeks2• 3 years ago

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!

Please expand on this. I have no idea how these two compare in efficiency (but apparently you do).

jaggederest2• 3 years ago

Thermal collectors, at best, can capture about 90% of the sun's energy. Practically speaking a bit less.

Solar panels, at their best, can capture about 25% of the sun's energy as electricity. There exist heat pumps with a coefficient of performance (COP) such that the system as a whole captures more heat i.e. COP >4

I'm not sure the claim is absolutely true universally, especially in challenging environments, but in a broad sense it is true that turning sunlight into electricity and then using that electricity to power a heat pump has a bunch of advantages over direct solar thermal, not least of which is air conditioning.

philjohn• 3 years ago

Can't comment on a thermal collector, but if we look at efficiency of solar PV and heat pumps:

Solar PV panel: the best ones are up to about 22% efficiency. Heat pumps: again, top of the line approaches 400%

You can't just multiply those numbers, however, there's also losses when you invert DC to AC, but it might be a good starting point.

archi42• 3 years ago

My key takeaway: GP is right, going PV+HP is a safe default; at least around here(!!). Unless you don't get money for selling excess power to the grid (batteries have become massively cheaper though) AND you have a gigantic roof. Even then, it's probably worthwhile investing more into the PV instead of getting solar thermal. Of course this also depends on latitude.

Anecdata 1: Thermal solar installation between 49 to 50deg latitutide, central europe. My uncle's SFH.

Anecdata 2: We're currently adding PV+HP with cooling capacity to our own SFH and I would have loved thermal solar to be great, so I looked into this. (same rough geographic location).

During summer his thermal solar has great efficiency, but the heat tanks are already charged after 1 to 2h (that's what he said when we talked about it last summer). So the installation has at most 2h of say 80% efficiency (during low solar radiation in the morning!) and then another 8h of 0% since the heat can go nowhere. This also wastes the huge energy peak after noon. This means: The ratio between a days "total energy harvested" vs "total energy which reached the collectors" is even less than the arithmetic average of 16% efficiency. Of course they use hot water over day, but that only increases the efficiency a little bit. Especially considering the physically huge tanks they have installed (probably 1000l ballpark, and I think there are two of these?!). Contrary in winter, the temperature differential between collector and fluid is so low that no heat/energy can be harvested at all. (At least for their installation and the winter temperatures around here).

Compare that to PV+HP: Any solar radiation is transformed to electricity with 22% efficiency. In summer the COP [see sibling comments] is very high, so you can still quickly charge that hot water tank and then use the remaining energy harvested for your home or car, or sell it to the grid. Plus the hot water tank can be smaller (less losses!) since you don't need to "store" all the excess energy. E.g. we have 200l hot water and 200l buffer for heating (or actually: Defrosting the HP). During winter the PV still produces some power that the HP can convert to heat (not too much and especially for less hours per day, but >0).

Maybe there are some sweet spots during spring and fall when solar thermal outperforms the PV+HP because it takes the whole day to charge the tanks. But then again when I installed my PV this spring, it produced >110% on a cool (16degC/60degF?), sunny day. So even during those seasons PV+HP are a tough competition.

Nice bonus for the PV+HP (that's what we're doing): If it's too hot in the summer, you can use the excess electricity to drive the HP in reverse mode for 7degC/44degF water temp in the "heating" system for active cooling. Due to condensation this requires dampproof insulation for the pipes, and convector units (sometimes also called "fan coils"?) to move enough air through the heat exchanger (car-like radiator) instead of traditional radiators or floor heating. But every convector can sink 1500W (5100 BTU?); for a room in a well-insulated house this can be enough.

Mind that our roof (south east + north west) has merely 60sqm per half, minus windows and other installations, so there is not too much space to add thermal solar. We get 0.07€ per kWh sold to the grid, so the excess PV mostly pays for itself. Battery is 11kWh usable, based on budget not "what we need" (data wasn't sufficient because we did all the renovations at once); this improves how much we can consume ourself; was more worthwhile than adding hot water tanks (we just can't consume that much hot water every day). We're also adding massive insulation to the 70y old house to slash heating requirements from >40MWh/y to something more sensible.

dacryn• 3 years ago

but thermal collectors are a lot cheaper than heat pumps, thats also important to consider

thsksbd3• 3 years ago

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.

aziaziazi5• 3 years ago

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...

thsksbd3• 3 years ago

If the water is not boiling you're going to need a very large system (for natural convection) or a pump.

bbojan• 3 years ago

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.

aziaziazi5• 3 years ago

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.

was_a_dev• 3 years ago

Driving a heat pump mechanically with a microhydro system would be interesting.

More consistent energy output paired with easy storage.

SoftTalker• 3 years ago

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• 3 years ago

A large tank, like the huge ones for heating oil in some old houses, would probably go a long way.

jv0010• 3 years ago

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

borh375• 3 years ago

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

mhh__• 3 years ago

And Szilard

fy202• 3 years ago

The vapour absorption cycle is similar in that it requires no moving parts. It's commercially used in caravan fridges, where propone is burnt as a heat source.

Tade0• 3 years ago

If you prefer to go even lower tech, check out compost heating:

https://www.happysprout.com/outdoor-living/compost-heating-g...

Unless you have pigs fed with swill, you'll easily produce enough compost to survive the winter in warmth.

rgmerk• 3 years ago

I get the appeal but there’s a reason commercial wind turbines are really big and located in optimal wind resources.

In short, the capacity factor of small wind turbines in the places most people will choose to live is terrible.

It may not be as satisfying but some combination of solar panels, batteries, and heat pumps (with the proviso that people in really cold climate either need to go ground based or have a backup) is going to work a hell of a lot better for anyone not living in the furious fifties.

ensocode• 3 years ago

Low Tech Magazine is a really inspiring page that I love to read, even if I am not particularly interested in windmills. Thanks a lot!

elihu• 3 years ago

"A mechanical heat pump is simply a heat pump without the electric motor – instead, the wind rotor is directly connected to the compressor(s) of the heat pump. This involves one less energy conversion, which makes the combination at least 10% more energy efficient than an electric heat pump driven by a wind turbine."

Running a heat pump directly from a turbine is a really interesting idea, but they overlook the main benefit that heat pumps achieve well over 100% efficiency, if you're just measuring how many watts of energy it takes to produce some number of watts of heat.

A reasonable setup might be to have a heat pump with an input shaft and a differential; one end goes to an electric motor, and the other end goes to a windmill. (Or a water wheel, or some other convenient source of rotational energy.) You could run the heat pump off the windmill, or if you don't need any more heat, the windmill can run into the motor as a generator. If you need heat and the wind isn't blowing, you can run the heat pump off the motor.

That's probably a less practical setup than just using an electric generator windmill and an electric heat pump, but one could argue that's in some sense simpler or more elegant.

2rsf• 3 years ago

Coincidentally I listened today to a podcast about direct water purification using wind turbines, the turbine is directly driving a water pump instead of going electricity->pump.

For water the benefits are not so much about efficiency, direct mechanical systems are the same or less efficient, but about simplicity and cost- those systems can be deployed and maintained in remote and poor areas without a need for costly technicians and parts.

20after4• 3 years ago

I wonder if a torque converter from an automobile transmission would make a good "off the shelf" joule machine. It would certainly work for producing heat from rotational motion but I wonder how it compares to using a water-based impeller.

almostnormal• 3 years ago

There's a practically infinite amount of sun and wind available.

The relevant metric for efficiency is not "heating done" over "sun or wind collected" but "heating possible" over "investment required".

A simple solution can outperform a more complex one.

eek2121• 3 years ago

It baffles me that (here in the US) we don’t take full advantage of the sun in newly built homes. Use the sun to heat water, generate electricity, etc.

I rarely see newly constructed homes include solar panels, much less anything else.

It seems like “every new home needs solar power” should be a thing.

Heat your house with a mechanical windmill (2019)

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