15 ms·

Heat Your House with a Water Brake Windmill

328 points by nyc111 8y ago

nmg 8y ago
Post links to front page. Direct link to article: https://www.lowtechmagazine.com/2019/02/heat-your-house-with-a-water-brake-windmill.html https://www.lowtechmagazine.com/2019/02/heat-your-house-with...
- nyc111 8y ago
  I don't know how that happened but now it won't let me update the URL now.
  - sctb 8y ago
    Updated. Thanks!
SketchySeaBeast 8y ago
I didn't see mention of the noise levels - I know that wind farms are noisy, I wonder how noisy a single windmill would be.
- deleted 8y ago
  [deleted]
- war1025 8y ago
  I have never found wind farms to be particularly noisy. Certainly not any more so than having a road nearby.
  - SketchySeaBeast 8y ago
    I did some research after I made that comment (as one typically does) and I wondering about use in an urban setting - it looks like the ambient noise would be much more obnoxious than anything the windmill puts out.
    - usrusr 8y ago
      Cities can be surprisingly quiet at night.
mauvehaus 8y ago
Related: Boil water with a blender: https://www.youtube.com/watch?v=GjcOobt9Ef8 https://www.youtube.com/watch?v=GjcOobt9Ef8
- itronitron 8y ago
  I wonder if this was ever used in a MacGyver episode.
seiferteric 8y ago
> one Joule equals the amount of energy required to raise the temperature of 1 cubic centimeter of water by 1 degree Celsius. I believe he meant 1 calorie, in Joules would be 4.184.
koala_man 8y ago
TL;DR: Everyone knows that solar can provide electricity at 20% efficiency or heat at 80% efficiency. Almost no one is aware that windmills can do the same. Instead of connecting a windmill to an electric turbine, you can have it churn a pool of water where friction raises the temperature without the conversion loss. Fascinating article. I had never considered this.
- mrfusion 8y ago
  I wonder if you could do even better having it turn a fan and compressor on a heat pump.
  - icebraining 8y ago
    The article talks about this in the "Retarders and Mechanical Heat Pumps" section.
- Symmetry 8y ago
  Electric motors/generators are typically much more than 20% efficient, the usual range is 75% to 95%. And you can use that energy for things besides heating on warm days. EDIT: The overall wind turbine isn't that efficient, that's the efficiency of the conversion of the mechanical rotation to electric power. There's a good deal of loss between the wind itself and rotation to vortices and whatnot.
  - deleted 8y ago
    [deleted]
- wallace_f 8y ago
  I am not a builder, but I wonder if tech like this is stymied by the nature of the housing market? From what I understand, housing is one of the most-regulated sectors, and one which has also seen not much innovation (compare to computers or autos). Were I a Bill Gates, I'd sponsor housing projects where innovators could be rewarded based on sustainability and cost. I guess, in order for anyone to live in them, I'd also have to sponsor some politicians to get government to then allow it. From an efficient resource allocation (in other words, economic) perspective, there appears to be almost noone solving sustainibility problems. What I mean is, sustainability per dollar spent should be at the forefront of our minds, and I'd be very surprised this kind of tech did not find a place in the market if that were allowed to prevail.
viburnum 8y ago
I wonder if this could be scaled up to provide district heating for villages and small towns.
- bluGill 8y ago
  They discuss this: yes but small is key here. It doesn't scale to large towns much less a city. (though if you take each neighborhood separately...) Losses from transmission are high.
  - jacobush 8y ago
    But no? It says small city. In my town we have residential heating for 100k people. It's a power plant dumping all of it's heat into the hot water grid. (Co-generation.) If there were windmills, at the power plant, or really just along the heat distribution waterworks, they could dump their heat into the hot water grid.
    - bluGill 8y ago
      Presumably your small city is using waste heat, so efficiency isn't as important: the goal is electric and the heat is just waste heat that needs to be dumped anyway. When there isn't the co-generation involved efficiency matters more. Note too that nobody has defined the actual size. Your idea of a small town could be larger than my idea of a large city. Local factors matter in this definition as well.
PietdeVries 8y ago
While the idea is new to me - using friction in a windmill to heat your house - the practical use in Western Europe could be limited. Installing a 12 meter windmill in my backyard is not going to happen... And then efficiency. A heatpump has a COP of around 4 or 5, so every 1 kW into the system results in 4 or 5 kW out. A heatpump uses electricity, which can be generated using a windmill, but also via solar panels. And a heatpump is relatively easy to link to your general central heating system. Now if you'd want to link your water-brake windmill to the central heating I guess it would be a 'different biscuit'. And since the smaller systems generate 3.5 kW with a firm breeze, you need backup. Suppose you'd not use a water-brake but a generator and heatpump; wouldn't the overall system efficiency be better in that situation? Or at least more convenient if you add solar panels in case there's no wind?
- icebraining 8y ago
  The article talks about this; it says the most efficient system is a mechanical heat pump (where the wind provides direct mechanical power to the compressor), but only for local generation, since heat transfer is much less efficient than electricity transfer.
  - ams6110 8y ago
    Yes, my thought was to use the windmill to run the heat pump, then buffer the heat as hot water in an insulated tank to heat the house. Not really practical unless you live in a place with fairly regular wind in the winter. Where I live, winter air tends to be fairly still with occasional exceptions and I could be wrong but I doubt it would be a great way to heat the house. Same with solar, in the dead of winter the sun is at quite a low angle in the sky, not even above the tree tops, and I doubt there's much to be gained either from photovoltaic solar or using it to directly heat water for the house.
    - harpastum 8y ago
      Electricity production in winter can definitely be lower, but it depends on latitude. As you might guess, near the equator there's almost no difference in season. According to the US Office of Energy Efficiency and Renewable Energy: "Countries such as the United States, which lie in the middle latitudes, receive more solar energy in the summer not only because days are longer, but also because the sun is nearly overhead. The sun's rays are far more slanted during the shorter days of the winter months. Cities such as Denver, Colorado, (near 40° latitude) receive nearly three times more solar energy in June than they do in December." [1] Looking at these maps [2][3] for solar production in January and July, it seems like a lot of places drop by around 50% summer to winter. So it's a significant drop, but unless you're extremely far north, there's still energy to be harvested. [1] https://www.energy.gov/eere/solar/articles/solar-radiation-basics https://www.energy.gov/eere/solar/articles/solar-radiation-b... [2] January: https://www.nrel.gov/gis/images/map_pv_us_january_dec2008.jpg https://www.nrel.gov/gis/images/map_pv_us_january_dec2008.jp... [3] July: https://www.nrel.gov/gis/images/map_pv_us_july_dec2008.jpg https://www.nrel.gov/gis/images/map_pv_us_july_dec2008.jpg
kazinator 8y ago
Electricity conversion: pretty darn efficient. Conveying the heat from a brake to a building: not so much.
- postalrat 8y ago
  You either live in a warmer climate or don't have electric heat.
- VBprogrammer 8y ago
  Conveying mechanical energy: reasonably efficient over modest distances. https://www.lowtechmagazine.com/2013/03/the-mechanical-transmission-of-power-3-wire-ropes.html https://www.lowtechmagazine.com/2013/03/the-mechanical-trans...
  - kazinator 8y ago
    Are you proposing some sort of chain, belt or shaft drive, such that the brake is actually housed inside the building?
    - VBprogrammer 8y ago
      Yes, that's what I was getting at. You can have the windmill located on a high point on the property (or just far away enough to be out of the way) then convey that energy back to near the house and use a brake to generate the heat near where it is needed.
- Someone 8y ago
  At small scale, why wouldn’t it be efficient? You can use the windmill to also drive a pump that pumps the water through, say, 20 meters of well-insulated pipe and from there through your floor heating system. Also, https://en.wikipedia.org/wiki/District_heating https://en.wikipedia.org/wiki/District_heating is at least somewhat competitive with other methods, so scaling up may be possible, too.
- seanalltogether 8y ago
  Yeah, this article seems like bad engineering, especially when the opening paragraph is trying to compare mechanical energy to solar heat. A windmill with a generator inside it that is hooked to a wire that drives an electric heating element inside your house will be more efficient then a water break inside an insulated chamber that pushes hot water through tubes into your home.
VBprogrammer 8y ago
I've come across this concept before. I think it might have been another post on the same site where they talk about direct mechanical use of hydro-power which made me look further into it. I wonder what the efficiency of using direct hydro / wind power to power an air compressor (say rejecting the excess heat to preheat the hot water supply) and releasing the compressed air for air conditioning.
beerlord 8y ago
So we are basically converting the rotation of the planet to heat.... hmmm. No wonder we are slowing down.
jdblair 8y ago
This impeller design is clever, but it seems that a DC generator and a resistive load would be an easier way to brake the windmill and generate heat. The first advantage is off-the-shelf parts. Electric generators and resistive loading are well known technologies. You can locate the resistive load (literally, an electric heating element) close to where you need the heat and there will be very little mechanical wear.
- bluGill 8y ago
  You are missing something important: they are storing enough heat to last for a couple weeks of no wind (or a cold snap). Enough DC batteries to heat a house that long are expensive and dangerous (fire hazard). A large water tank (10 tons of water or more!) is a lot safer to have around the house. The water tank also means the ability to locate your load anywhere isn't important: either way you have to design your system around the tank. Also, DC is less efficient as the losses at your generator is heat that isn't captured. Generators are typically 80-90% efficient. This is pedantic though and doesn't matter (if this was the only concern DC is wroth the losses because you can divert it to lights or something else that is also useful)
  - jdblair 8y ago
    I didn't spell everything out. I never suggested you store the electricity in batteries. The electric heater would be used to heat some mass, like a tank of water or bricks. I look at this impeller and I see a custom mechanical design, with seals that are prone to failure. You replace that with an off-the-shelf DC motor and a resister bank in a tank of water, and you can put the tank of water in your basement or wherever you already have the heater for your hot-water heating system.
    - apendleton 8y ago
      They also discuss an "eddy current retarder" design, which uses a magnetic mechanism that sounds vaguely like an electric generator but generates heat directly, as an alternative to the water break/impeller design. Sounds like maybe you get the best of both worlds, in terms of a smaller package but avoiding the motion -> electricity -> heat conversion losses due to the extra step.
apo 8y ago
The Joule Machine was originally conceived as a measuring apparatus. James Joule built it in the 1840s for his famous measurement of the mechanical equivalent of heat: one Joule equals the amount of energy required to raise the temperature of 1 cubic centimeter of water by 1 degree Celsius. Although this confuses the definition of joule with calorie, Joule's experiment was brilliant and laid the groundwork for the laws of thermodynamics: https://en.wikipedia.org/wiki/Mechanical_equivalent_of_heat https://en.wikipedia.org/wiki/Mechanical_equivalent_of_heat A weight was suspended from a rope and allowed to fall. The falling weight was mechanically coupled to a paddle in a pool of water. As the weight fell slowly, it turned the paddle. Given that the mass of the weight and the water were known, the work performed by the falling weight and the heat absorbed by the water could be quantitated. Here's a kitchen test of the principle where a household blender is used to boil water: https://www.youtube.com/watch?v=GjcOobt9Ef8 https://www.youtube.com/watch?v=GjcOobt9Ef8 I suspect some heat transfer from the motor through the blades, but it's very surprising the water boils. He could have run a calculation, based on the power output of the blender, to see if the temperature increase was reasonable.
- theoh 8y ago
  Joule's apparatus can be seen at the Science Museum in London. https://commons.wikimedia.org/wiki/File:Joule_Apparatus.jpg https://commons.wikimedia.org/wiki/File:Joule_Apparatus.jpg It's a beautiful device, worth googling around for the various photos that are online. I would embed a few choice images that I found but of course HN doesn't allow that. rolling eyes emoji There's also an old Open University programme which reconstructed his experiment (conducted on his honeymoon, allegedly). It doesn't appear to be on YouTube.
ip26 8y ago
Just for fun, here's a link to their solar+storage server: https://solar.lowtechmagazine.com/2019/02/heat-your-house-with-a-water-brake-windmill.html https://solar.lowtechmagazine.com/2019/02/heat-your-house-wi... https://solar.lowtechmagazine.com/about/ https://solar.lowtechmagazine.com/about/
markovbot 8y ago
>The owner of this website (www.lowtechmagazine.com) has banned your IP address (x.x.x.x). Anyone else getting this? I'm just going to read it on archive.org but it seems weird. I'm coming from a Digital Ocean NYC IP
- LinuxBender 8y ago
  Some sites block VPS's to mitigate bot abuse. Some just send you to endless captchas. Others block in haproxy. Some just 'ip route add blackhole ${ip}'
toss1 8y ago
Great concept to reduce the losses in transmitting and converting energy, and reducing the weight, complexity, and cost of the wind system. But there are issues. 1) It takes a rather large system and stiff breeze, "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", ~25mph wind, to produce a modest heating output. that is the equivalent of two small 1750 watt heaters, which would barely heat a decent size room in cold weather. 2) The system is completely dedicated to heat production, and will be a waste of space over half the year. In the summer, most of the wind will be of essentially no use except for warm tap water. In contrast, you can use electrical generation any time. The best system I've seen of this was at a remote boarding school in Florida. On the roof, they had black serpentine pipes in flat black boxes with glass lids, so mini-greenhouses. In the utility area, they had large insulated water storage tanks. They could get the water to 180F, and had to warn people to be careful when using the tap or taking showers. Pretty impressive, and this was decades ago.
benj111 8y ago
It occurs to me that this could be combined with a standard wind turbine. I assume turbines already generate heat, and they also require brakes for when wind speed gets too high. Best case you could be generating maximum electricity and using the brake to generate useful heat. I guess this would aid dispatchability of the electricity, certainly with regards to limiting output as well.
carapace 8y ago
Kind of a tangent, but also check out the Ranque-Hilsch vortex tube, "a mechanical device that separates a compressed gas into hot and cold streams" - https://en.wikipedia.org/wiki/Vortex_tube https://en.wikipedia.org/wiki/Vortex_tube
roland35 8y ago
I worked on a wind turbine related project for some time and while I overall love renewable energy wind does have a few factors which can limit its effectiveness. This applies for heat as well as electric generation. - As noted in the article, wind can be highly variable in most areas. Optimizing a wind turbine for the average low speed (like here in the US Midwest) means that at super high speed winds can damage your turbine and it may need to be shut off. If you optimize for the high speeds you can get a ton of energy at those speeds but your turbine will mostly be still. Regions with a nice steady wind profile work better for power generation. - Wind turbines with variable pitch blades do exist but add cost and mechanical complexity. - Turbines often are installed at remote locations and maintence is difficult. One crazy story is a friend of a coworker was a tech for the giant wind turbines and fell INTO those giant fiberglass blades and almost died wedged in there before he could be rescued! - "Urban" wind turbines was an idea here in Cleveland a few years ago, but wind turbines generate a lot of vibration which isn't good for buildings. Plus the turbines don't always spin all the time which is bad PR! All this said I think wind power can be a part of a good energy portfolio but like with anything in engineering it boils down to a big "but if.."!!
- dgzl 8y ago
  > Wind turbines with variable pitch blades do exist but add cost and mechanical complexity. I was about to suggest the idea of using gears like from a vehicle's transmission (i.e. first gear is easy to turn, will shift to larger when certain condition achieved), but it sounds like these ideas have been hashed out already.
  - richardhod 8y ago
    Yes, I'm curious about this, and a FAQ on the technical limitations which lead to the situation that GP mentions. I'd have thought that you could have a mechanical / electrical brake on the blades to keep velocities reasonable, or gears as uyou mention, or maybe it's other mechanical stresses.
    - Gibbon1 8y ago
oftenwrong 8y ago
There are two stories for this URL: https://news.ycombinator.com/item?id=19263814 https://news.ycombinator.com/item?id=19263814 (this one) and https://news.ycombinator.com/item?id=19263603 https://news.ycombinator.com/item?id=19263603 I would have expected the anti-duplicate-submission mechanism to prevent one of these from being created, redirecting the later submitter to the already-existing story, given that these were both submitted around the same time.
Animats 8y ago
The article doesn't show a single non-demo installation. This thing looks like a giant mechanical kludge. If you put the brake (the paddles in water part) at the top of the tower, you have to pump water up the tower. If you put it at the bottom of the tower, you need a top gearbox with a right-angle bevel drive, a bearing ring supporting the gearbox so it can face the wind, long shafting, and bearings. Some early power turbines were built that way, but nobody does that any more. Vertical axis turbines like the Savonius turbine and Darrieus rotor can be used, but they're not very efficient, so you need a big one. They also are hard to shut down in an overspeed condition; they can't change direction, change blade pitch, or tilt upward, so you need a strong emergency brake system. Which is why they're rarely seen any more. All this outdoor hot water plumbing needs to be well insulated, or you lose most of the heat. So a field of wind turbines, or one unit some distance from where the heat is wanted, is a problem. Moving energy around over wires is so much simpler. Driving a heat pump mechanically might work better, but that's because heat pumps are far more efficient than heaters. (Moving heat is much cheaper than making it. See [1]). An electric windmill driving a heat pump is probably less hassle. [1] https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/
- lowtechmagazine 8y ago
  "The article doesn't show a single non-demo installation". It does. The Calorius windmill was commercially produced for about a decade, 40 of them were sold. Seventeen of these windmills were still operating in 2012. It's all in the article. Also your points about the savonius are addressed.
  - D_Alex 8y ago
    Your article is interesting, but it makes a number of incorrect or misleading claims, the chief one being that heating via electricity produced by wind or PV is inefficient. On the contrary, it is cheap, uncomplicated and very efficient in the modern context - by using the electric power to run a reverse cycle AC unit (in most cases, existing) you will get around 10 times the heat that a water brake system might deliver, with lower cost and much higher reliability.
pkulak 8y ago
Seems like generating power to feed to a heat pump would still be more efficient, despite electrical losses, considering that good heat pumps can be 3x more efficient than friction/resistive heating.
- Topgamer7 8y ago
  One of the main benefits of the water brake system is the storage of heat. With a sufficiently large insulated tank, you can retain head for days to weeks when the wind subsides. The water brake gives you a little more insurance compared to electricity generation for an off-grid solution.
  - mdorazio 8y ago
    Why couldn't you use a heat pump to heat an insulated tank and get the same benefit?
  - atoav 8y ago
    The problem is wind can be unreliable. With a electrical system you are way more flexible.You can use the generated electricity if you don’t need heat and if you are in the winter in a period without much wind you can fall back on solar or grid. Unless you live in an area with very steady wind during the winter and a more or less equal need for heat all year around, the electrical solution is more practical even if it is less efficient. I could imagine this for warm water with a different system used for heating or something like that.
VBprogrammer 8y ago
Whenever I read anything about wind turbines I'm reminded of this article. It's a shame the photos are missing at the moment. Maybe Jacques is around somewhere and can restore them. https://jacquesmattheij.com/how-to-build-a-windmill/ https://jacquesmattheij.com/how-to-build-a-windmill/
- ashtonbaker 8y ago
  The photos are working in the Wayback Machine: https://web.archive.org/web/20160813143636/http://www.jacquesmattheij.com/how-to-build-a-windmill https://web.archive.org/web/20160813143636/http://www.jacque...
golemiprague 8y ago
Heating water by the sun is very common in Israel since the 1950'. It is not working with solar panels but rather with a system that works more or less like this: Cold water is pumped (or flows by pressure) to the collector where the sun heats it. The heated water flows back to the collection tank. Since hot water is lighter than cold water, the heated water in the pipes moves up towards the tank, which sits at a higher level, and the cold water sinks from the tank to the bottom of the collector, creating a natural circulation cycle.
mark-r 8y ago
Can anyone explain to the ignorant among us (i.e. me) why converting to heat is so much more efficient than converting to electricity? The article makes the claim but doesn't back it up. What are the losses involved with each approach?
- deleted 8y ago
  [deleted]
- bluGill 8y ago
  Ultimately all approaches convert to heat with 100% efficiency. However the in between stages and what you do with the heat are in question. A Generator is 80-90% efficient in general, then you have battery charging losses (which I do not know), then battery discharge losses, finally, you have power transmission losses to get the electric around. All of the above losses are not captured. They are claiming that because everything is converted directly to heat near where it is used their total losses are less. (they assume insulation here) The losses in their system are gears (some of which exist in most generator systems), and tank losses over time. It is plausible they are right. However it all depends on local install factors which can be manipulated either way.
- sleavey 8y ago
  I think the main point the article was eluding to was that if you use wind power to first generate electricity then convert this into heat, you have two conversion steps with loss: wind to electricity, and then electricity to heat. The overall efficiency is then the product of the efficiencies of the two steps. If you produce heat directly from wind, you cut out one conversion with its associated inefficiency.
  - mark-r 8y ago
    I always figured electricity to heat was nearly 100% efficient, it's the generating of electricity where the losses occur.
kristiandupont 8y ago
I've heard several times that electrical heaters of any kind are expensive and much less efficient than other heat sources and I feel like I am throwing money out of the window when I turn them on. This doesn't make any sense to me though. Can someone with a better understanding of physics than me explain to me why this would be the case? I would imagine electricity to be just about the most efficient way to transfer energy. And furthermore, as I understand it, lost energy tends to become heat!
- dec0dedab0de 8y ago
  Because in order to get the electricity to your house the power plant had to first do whatever it needed to do to generate the electricity. for example if the power plant is burning oil, and converting that to electricity, then you convert that electricity to heat you're going to get much less heat than just burning the oil yourself.
  - dragonwriter 8y ago
    > for example if the power plant is burning oil, and converting that to electricity, then you convert that electricity to heat you're going to get much less heat than just burning the oil yourself. OTOH, the power plant probably has a rail connection or pipeline for oil, and the marginal energy cost of transporting an additional unit of oil to the power plant is probably quite low compared to the marginal energy cost of transporting the same additional unit of oil to your house.
    - dec0dedab0de 8y ago
      I'm not sure about that. I usually get about 125 gallons at a time. And since heating oil is just diesel with dye in it, we can just add deliver costs in gallons. Even assuming im the only delivery, I doubt it would take more than a gallon of gas to travel to my house. But to be safe lets say 5. With the above assumption, the question is Could 130 gallons burned at a power plant generate more heat in my house via electricity. Than 125 gallons burned in my house directly. I dont know enough to give an answer but my gut says no.
frankus 8y ago
I nearly flunked thermodynamics in college, so take this as the harebrained scheme/Burning Man hack that it would be. But I've wondered if you could get a useful amount of cooling/greywater disposal/hot clean water supply by mounting a wind-powered vacuum pump on top of a tall (11m +) column of water so that the water in the column would boil at ambient temperature.
- tlb 8y ago
  It turns out that water boils quite slowly at room temperature and low pressure, so you’d need a very large surface area.
netjiro 8y ago
Or, wind -> electricity -> heat pump (1:5) -> lots of heat?
ggm 8y ago
The obvious critique is that people in extreme poverty deserve every attention moment they can get, to derive a benefit with the lowest cost (to them) possible. But, when this represents an ad-hoc, it can often leave them stranded on a low increment from zero. So, adding proper drains to a favela is good because it reduces child mortality from bad drains, but its still a slum: the fix is unclear but probably involves a revolution. These mechanisms are good because they can be easily understood and whilst they will require patching and hacking and repair and are inefficient and can't do all things, if they can provide a stable heat source to remove the burden of burning things, which actually kills more women and children because of lack of oxygen, CO/CO2 poisoning, asthma and other effects, there is a huge positive upside. But, as has been said since at least the 1920s what we really need is soviet power, plus electricity.
aaron695 8y ago
Windmills are to noisy for cities (not necessarily it's claim) Large windmills have limits of ~300 meters from houses, not sure about small ones but unless you can cheaply get it to 5 meters, it's a fail. We know city noise kills, home windmills ramping up and down can't be good. It's have to be up there with cars and air conditioners / heat pumps. https://www.ge.com/reports/post/92442325225/how-loud-is-a-wind-turbine/ https://www.ge.com/reports/post/92442325225/how-loud-is-a-wi... Meh -https://www.theguardian.com/lifeandstyle/2018/jul/03/sonic-doom-noise-pollution-kills-heart-disease-diabetes https://www.theguardian.com/lifeandstyle/2018/jul/03/sonic-d...
QuamStiver 8y ago
I am curious about the potential for a hybrid wind turbine (clutchable): Generate electricity during peak hours (high price) / Generate storable heat during off-peak hours. Or would it be better to generate e-power all the time if the turbine is capable of it?
neilwilson 8y ago
Why do we keep trying to come up with ways to heat things when a human is a 100 watt heater at rest? Just insulate the building properly and then you can use rooftop solar to cool it down on those days when it gets too hot - largely because the sun is shining. Moving heat is generally easier than generating it.
- speedplane 8y ago
  Unless you live in a styrofoam box, you're going to need heating. Also, people like windows.
  - neilwilson 8y ago
    PassivHaus standard can be warmed with a 1Kw heater at -10 degrees celsius. They have windows, doors and mechanical ventilation.
    - speedplane 8y ago
      I just read about Passive House, thanks for citing it. The standard requires less 15kWh/m^2 per year. I live in the U.S. in a 1200 sq ft apartment, small for U.S. standards, and that comes to ~4.5kwH per day. To put that in perspective, an 80 Watt computer running all day uses up nearly half of that margin. A small 6000 BTU A/C (good enough for a small bedroom) uses up the entire allowance if you run it for 8 hours in your bedroom while sleeping. An electric dryer will use up the entire allowance if you do two loads of clothing. I love that people are thinking about this, and I truly hope that it becomes standard, but it's not exactly reasonable for folks to expect such a level of efficiency without paying through the nose.
- benj111 8y ago
  This seems like a reasonable argument for wearing a jumper. I think you're firmly into diminishing returns if you're insulating your house to be warmed purely by body heat through the depths of winter. Plus what happens if you have a child? Do you remove insulation, run the AC through winter?
AltmousGadfly 8y ago
What I don't quite understand is: heat will be a byproduct of using electricity anyway, since it is always the waste product in the end. So why not generate electricity that can be put to good use first?
GrryDucape 8y ago
Another model could be to run an air compressor from the turbine. Compression will give you a heater, and then releasing the compressed air will give you cooling. Thinking about it some more, you should also be able to get kinetic energy out (or electricity) and water, by running a turbine on the compressed air and collecting moisture from the cooled air. Essentially one of these: https://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cycle#Gas_cycle https://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cy... - they're not technically as efficient as a phase change, but if it's simpler and there are fewer moving parts, it might be a win.
severak_cz 8y ago
The point of the article is that (unlike people would expect) THERE IS a direct way how to convert mechanical energy to heat. It can be even more effective (in theory) than heating via electricity from wind, because there is only one energy conversion (motion -> heat unlike motion -> electricity -> heat). Big downside is that heating with water brake is somewhat impractical and unexplored territory. However big plus of this approach is that you can make water brake with middle-age technology.

328 points by nyc111 8y ago

nmg 8y ago

Post links to front page. Direct link to article: https://www.lowtechmagazine.com/2019/02/heat-your-house-with-a-water-brake-windmill.html https://www.lowtechmagazine.com/2019/02/heat-your-house-with...

nyc111 8y ago
I don't know how that happened but now it won't let me update the URL now.
- sctb 8y ago
  Updated. Thanks!

SketchySeaBeast 8y ago

I didn't see mention of the noise levels - I know that wind farms are noisy, I wonder how noisy a single windmill would be.

deleted 8y ago
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war1025 8y ago
I have never found wind farms to be particularly noisy. Certainly not any more so than having a road nearby.
- SketchySeaBeast 8y ago
  I did some research after I made that comment (as one typically does) and I wondering about use in an urban setting - it looks like the ambient noise would be much more obnoxious than anything the windmill puts out.
  - usrusr 8y ago
    Cities can be surprisingly quiet at night.

mauvehaus 8y ago

Related: Boil water with a blender: https://www.youtube.com/watch?v=GjcOobt9Ef8 https://www.youtube.com/watch?v=GjcOobt9Ef8

itronitron 8y ago
I wonder if this was ever used in a MacGyver episode.

seiferteric 8y ago

> one Joule equals the amount of energy required to raise the temperature of 1 cubic centimeter of water by 1 degree Celsius. I believe he meant 1 calorie, in Joules would be 4.184.

koala_man 8y ago

TL;DR: Everyone knows that solar can provide electricity at 20% efficiency or heat at 80% efficiency. Almost no one is aware that windmills can do the same. Instead of connecting a windmill to an electric turbine, you can have it churn a pool of water where friction raises the temperature without the conversion loss. Fascinating article. I had never considered this.

mrfusion 8y ago
I wonder if you could do even better having it turn a fan and compressor on a heat pump.
- icebraining 8y ago
  The article talks about this in the "Retarders and Mechanical Heat Pumps" section.
Symmetry 8y ago
Electric motors/generators are typically much more than 20% efficient, the usual range is 75% to 95%. And you can use that energy for things besides heating on warm days. EDIT: The overall wind turbine isn't that efficient, that's the efficiency of the conversion of the mechanical rotation to electric power. There's a good deal of loss between the wind itself and rotation to vortices and whatnot.
- deleted 8y ago
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wallace_f 8y ago
I am not a builder, but I wonder if tech like this is stymied by the nature of the housing market? From what I understand, housing is one of the most-regulated sectors, and one which has also seen not much innovation (compare to computers or autos). Were I a Bill Gates, I'd sponsor housing projects where innovators could be rewarded based on sustainability and cost. I guess, in order for anyone to live in them, I'd also have to sponsor some politicians to get government to then allow it. From an efficient resource allocation (in other words, economic) perspective, there appears to be almost noone solving sustainibility problems. What I mean is, sustainability per dollar spent should be at the forefront of our minds, and I'd be very surprised this kind of tech did not find a place in the market if that were allowed to prevail.

viburnum 8y ago

I wonder if this could be scaled up to provide district heating for villages and small towns.

bluGill 8y ago
They discuss this: yes but small is key here. It doesn't scale to large towns much less a city. (though if you take each neighborhood separately...) Losses from transmission are high.
- jacobush 8y ago
  But no? It says small city. In my town we have residential heating for 100k people. It's a power plant dumping all of it's heat into the hot water grid. (Co-generation.) If there were windmills, at the power plant, or really just along the heat distribution waterworks, they could dump their heat into the hot water grid.
  - bluGill 8y ago
    Presumably your small city is using waste heat, so efficiency isn't as important: the goal is electric and the heat is just waste heat that needs to be dumped anyway. When there isn't the co-generation involved efficiency matters more. Note too that nobody has defined the actual size. Your idea of a small town could be larger than my idea of a large city. Local factors matter in this definition as well.

PietdeVries 8y ago

While the idea is new to me - using friction in a windmill to heat your house - the practical use in Western Europe could be limited. Installing a 12 meter windmill in my backyard is not going to happen... And then efficiency. A heatpump has a COP of around 4 or 5, so every 1 kW into the system results in 4 or 5 kW out. A heatpump uses electricity, which can be generated using a windmill, but also via solar panels. And a heatpump is relatively easy to link to your general central heating system. Now if you'd want to link your water-brake windmill to the central heating I guess it would be a 'different biscuit'. And since the smaller systems generate 3.5 kW with a firm breeze, you need backup. Suppose you'd not use a water-brake but a generator and heatpump; wouldn't the overall system efficiency be better in that situation? Or at least more convenient if you add solar panels in case there's no wind?

icebraining 8y ago
The article talks about this; it says the most efficient system is a mechanical heat pump (where the wind provides direct mechanical power to the compressor), but only for local generation, since heat transfer is much less efficient than electricity transfer.
- ams6110 8y ago
  Yes, my thought was to use the windmill to run the heat pump, then buffer the heat as hot water in an insulated tank to heat the house. Not really practical unless you live in a place with fairly regular wind in the winter. Where I live, winter air tends to be fairly still with occasional exceptions and I could be wrong but I doubt it would be a great way to heat the house. Same with solar, in the dead of winter the sun is at quite a low angle in the sky, not even above the tree tops, and I doubt there's much to be gained either from photovoltaic solar or using it to directly heat water for the house.
  - harpastum 8y ago
    Electricity production in winter can definitely be lower, but it depends on latitude. As you might guess, near the equator there's almost no difference in season. According to the US Office of Energy Efficiency and Renewable Energy: "Countries such as the United States, which lie in the middle latitudes, receive more solar energy in the summer not only because days are longer, but also because the sun is nearly overhead. The sun's rays are far more slanted during the shorter days of the winter months. Cities such as Denver, Colorado, (near 40° latitude) receive nearly three times more solar energy in June than they do in December." [1] Looking at these maps [2][3] for solar production in January and July, it seems like a lot of places drop by around 50% summer to winter. So it's a significant drop, but unless you're extremely far north, there's still energy to be harvested. [1] https://www.energy.gov/eere/solar/articles/solar-radiation-basics https://www.energy.gov/eere/solar/articles/solar-radiation-b... [2] January: https://www.nrel.gov/gis/images/map_pv_us_january_dec2008.jpg https://www.nrel.gov/gis/images/map_pv_us_january_dec2008.jp... [3] July: https://www.nrel.gov/gis/images/map_pv_us_july_dec2008.jpg https://www.nrel.gov/gis/images/map_pv_us_july_dec2008.jpg

kazinator 8y ago

Electricity conversion: pretty darn efficient. Conveying the heat from a brake to a building: not so much.

postalrat 8y ago
You either live in a warmer climate or don't have electric heat.
VBprogrammer 8y ago
Conveying mechanical energy: reasonably efficient over modest distances. https://www.lowtechmagazine.com/2013/03/the-mechanical-transmission-of-power-3-wire-ropes.html https://www.lowtechmagazine.com/2013/03/the-mechanical-trans...
- kazinator 8y ago
  Are you proposing some sort of chain, belt or shaft drive, such that the brake is actually housed inside the building?
  - VBprogrammer 8y ago
    Yes, that's what I was getting at. You can have the windmill located on a high point on the property (or just far away enough to be out of the way) then convey that energy back to near the house and use a brake to generate the heat near where it is needed.
Someone 8y ago
At small scale, why wouldn’t it be efficient? You can use the windmill to also drive a pump that pumps the water through, say, 20 meters of well-insulated pipe and from there through your floor heating system. Also, https://en.wikipedia.org/wiki/District_heating https://en.wikipedia.org/wiki/District_heating is at least somewhat competitive with other methods, so scaling up may be possible, too.
seanalltogether 8y ago
Yeah, this article seems like bad engineering, especially when the opening paragraph is trying to compare mechanical energy to solar heat. A windmill with a generator inside it that is hooked to a wire that drives an electric heating element inside your house will be more efficient then a water break inside an insulated chamber that pushes hot water through tubes into your home.

VBprogrammer 8y ago

I've come across this concept before. I think it might have been another post on the same site where they talk about direct mechanical use of hydro-power which made me look further into it. I wonder what the efficiency of using direct hydro / wind power to power an air compressor (say rejecting the excess heat to preheat the hot water supply) and releasing the compressed air for air conditioning.

beerlord 8y ago

So we are basically converting the rotation of the planet to heat.... hmmm. No wonder we are slowing down.

jdblair 8y ago

This impeller design is clever, but it seems that a DC generator and a resistive load would be an easier way to brake the windmill and generate heat. The first advantage is off-the-shelf parts. Electric generators and resistive loading are well known technologies. You can locate the resistive load (literally, an electric heating element) close to where you need the heat and there will be very little mechanical wear.

bluGill 8y ago
You are missing something important: they are storing enough heat to last for a couple weeks of no wind (or a cold snap). Enough DC batteries to heat a house that long are expensive and dangerous (fire hazard). A large water tank (10 tons of water or more!) is a lot safer to have around the house. The water tank also means the ability to locate your load anywhere isn't important: either way you have to design your system around the tank. Also, DC is less efficient as the losses at your generator is heat that isn't captured. Generators are typically 80-90% efficient. This is pedantic though and doesn't matter (if this was the only concern DC is wroth the losses because you can divert it to lights or something else that is also useful)
- jdblair 8y ago
  I didn't spell everything out. I never suggested you store the electricity in batteries. The electric heater would be used to heat some mass, like a tank of water or bricks. I look at this impeller and I see a custom mechanical design, with seals that are prone to failure. You replace that with an off-the-shelf DC motor and a resister bank in a tank of water, and you can put the tank of water in your basement or wherever you already have the heater for your hot-water heating system.
  - apendleton 8y ago
    They also discuss an "eddy current retarder" design, which uses a magnetic mechanism that sounds vaguely like an electric generator but generates heat directly, as an alternative to the water break/impeller design. Sounds like maybe you get the best of both worlds, in terms of a smaller package but avoiding the motion -> electricity -> heat conversion losses due to the extra step.

apo 8y ago

The Joule Machine was originally conceived as a measuring apparatus. James Joule built it in the 1840s for his famous measurement of the mechanical equivalent of heat: one Joule equals the amount of energy required to raise the temperature of 1 cubic centimeter of water by 1 degree Celsius. Although this confuses the definition of joule with calorie, Joule's experiment was brilliant and laid the groundwork for the laws of thermodynamics: https://en.wikipedia.org/wiki/Mechanical_equivalent_of_heat https://en.wikipedia.org/wiki/Mechanical_equivalent_of_heat A weight was suspended from a rope and allowed to fall. The falling weight was mechanically coupled to a paddle in a pool of water. As the weight fell slowly, it turned the paddle. Given that the mass of the weight and the water were known, the work performed by the falling weight and the heat absorbed by the water could be quantitated. Here's a kitchen test of the principle where a household blender is used to boil water: https://www.youtube.com/watch?v=GjcOobt9Ef8 https://www.youtube.com/watch?v=GjcOobt9Ef8 I suspect some heat transfer from the motor through the blades, but it's very surprising the water boils. He could have run a calculation, based on the power output of the blender, to see if the temperature increase was reasonable.

theoh 8y ago
Joule's apparatus can be seen at the Science Museum in London. https://commons.wikimedia.org/wiki/File:Joule_Apparatus.jpg https://commons.wikimedia.org/wiki/File:Joule_Apparatus.jpg It's a beautiful device, worth googling around for the various photos that are online. I would embed a few choice images that I found but of course HN doesn't allow that. rolling eyes emoji There's also an old Open University programme which reconstructed his experiment (conducted on his honeymoon, allegedly). It doesn't appear to be on YouTube.

ip26 8y ago

Just for fun, here's a link to their solar+storage server: https://solar.lowtechmagazine.com/2019/02/heat-your-house-with-a-water-brake-windmill.html https://solar.lowtechmagazine.com/2019/02/heat-your-house-wi... https://solar.lowtechmagazine.com/about/ https://solar.lowtechmagazine.com/about/

markovbot 8y ago

>The owner of this website (www.lowtechmagazine.com) has banned your IP address (x.x.x.x). Anyone else getting this? I'm just going to read it on archive.org but it seems weird. I'm coming from a Digital Ocean NYC IP

LinuxBender 8y ago
Some sites block VPS's to mitigate bot abuse. Some just send you to endless captchas. Others block in haproxy. Some just 'ip route add blackhole ${ip}'

toss1 8y ago

Great concept to reduce the losses in transmitting and converting energy, and reducing the weight, complexity, and cost of the wind system. But there are issues. 1) It takes a rather large system and stiff breeze, "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", ~25mph wind, to produce a modest heating output. that is the equivalent of two small 1750 watt heaters, which would barely heat a decent size room in cold weather. 2) The system is completely dedicated to heat production, and will be a waste of space over half the year. In the summer, most of the wind will be of essentially no use except for warm tap water. In contrast, you can use electrical generation any time. The best system I've seen of this was at a remote boarding school in Florida. On the roof, they had black serpentine pipes in flat black boxes with glass lids, so mini-greenhouses. In the utility area, they had large insulated water storage tanks. They could get the water to 180F, and had to warn people to be careful when using the tap or taking showers. Pretty impressive, and this was decades ago.

benj111 8y ago

It occurs to me that this could be combined with a standard wind turbine. I assume turbines already generate heat, and they also require brakes for when wind speed gets too high. Best case you could be generating maximum electricity and using the brake to generate useful heat. I guess this would aid dispatchability of the electricity, certainly with regards to limiting output as well.

carapace 8y ago

Kind of a tangent, but also check out the Ranque-Hilsch vortex tube, "a mechanical device that separates a compressed gas into hot and cold streams" - https://en.wikipedia.org/wiki/Vortex_tube https://en.wikipedia.org/wiki/Vortex_tube

roland35 8y ago

I worked on a wind turbine related project for some time and while I overall love renewable energy wind does have a few factors which can limit its effectiveness. This applies for heat as well as electric generation. - As noted in the article, wind can be highly variable in most areas. Optimizing a wind turbine for the average low speed (like here in the US Midwest) means that at super high speed winds can damage your turbine and it may need to be shut off. If you optimize for the high speeds you can get a ton of energy at those speeds but your turbine will mostly be still. Regions with a nice steady wind profile work better for power generation. - Wind turbines with variable pitch blades do exist but add cost and mechanical complexity. - Turbines often are installed at remote locations and maintence is difficult. One crazy story is a friend of a coworker was a tech for the giant wind turbines and fell INTO those giant fiberglass blades and almost died wedged in there before he could be rescued! - "Urban" wind turbines was an idea here in Cleveland a few years ago, but wind turbines generate a lot of vibration which isn't good for buildings. Plus the turbines don't always spin all the time which is bad PR! All this said I think wind power can be a part of a good energy portfolio but like with anything in engineering it boils down to a big "but if.."!!

dgzl 8y ago
> Wind turbines with variable pitch blades do exist but add cost and mechanical complexity. I was about to suggest the idea of using gears like from a vehicle's transmission (i.e. first gear is easy to turn, will shift to larger when certain condition achieved), but it sounds like these ideas have been hashed out already.
- richardhod 8y ago
  Yes, I'm curious about this, and a FAQ on the technical limitations which lead to the situation that GP mentions. I'd have thought that you could have a mechanical / electrical brake on the blades to keep velocities reasonable, or gears as uyou mention, or maybe it's other mechanical stresses.
  - Gibbon1 8y ago

oftenwrong 8y ago

There are two stories for this URL: https://news.ycombinator.com/item?id=19263814 https://news.ycombinator.com/item?id=19263814 (this one) and https://news.ycombinator.com/item?id=19263603 https://news.ycombinator.com/item?id=19263603 I would have expected the anti-duplicate-submission mechanism to prevent one of these from being created, redirecting the later submitter to the already-existing story, given that these were both submitted around the same time.

Animats 8y ago

The article doesn't show a single non-demo installation. This thing looks like a giant mechanical kludge. If you put the brake (the paddles in water part) at the top of the tower, you have to pump water up the tower. If you put it at the bottom of the tower, you need a top gearbox with a right-angle bevel drive, a bearing ring supporting the gearbox so it can face the wind, long shafting, and bearings. Some early power turbines were built that way, but nobody does that any more. Vertical axis turbines like the Savonius turbine and Darrieus rotor can be used, but they're not very efficient, so you need a big one. They also are hard to shut down in an overspeed condition; they can't change direction, change blade pitch, or tilt upward, so you need a strong emergency brake system. Which is why they're rarely seen any more. All this outdoor hot water plumbing needs to be well insulated, or you lose most of the heat. So a field of wind turbines, or one unit some distance from where the heat is wanted, is a problem. Moving energy around over wires is so much simpler. Driving a heat pump mechanically might work better, but that's because heat pumps are far more efficient than heaters. (Moving heat is much cheaper than making it. See [1]). An electric windmill driving a heat pump is probably less hassle. [1] https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/

lowtechmagazine 8y ago
"The article doesn't show a single non-demo installation". It does. The Calorius windmill was commercially produced for about a decade, 40 of them were sold. Seventeen of these windmills were still operating in 2012. It's all in the article. Also your points about the savonius are addressed.
- D_Alex 8y ago
  Your article is interesting, but it makes a number of incorrect or misleading claims, the chief one being that heating via electricity produced by wind or PV is inefficient. On the contrary, it is cheap, uncomplicated and very efficient in the modern context - by using the electric power to run a reverse cycle AC unit (in most cases, existing) you will get around 10 times the heat that a water brake system might deliver, with lower cost and much higher reliability.

pkulak 8y ago

Seems like generating power to feed to a heat pump would still be more efficient, despite electrical losses, considering that good heat pumps can be 3x more efficient than friction/resistive heating.

Topgamer7 8y ago
One of the main benefits of the water brake system is the storage of heat. With a sufficiently large insulated tank, you can retain head for days to weeks when the wind subsides. The water brake gives you a little more insurance compared to electricity generation for an off-grid solution.
- mdorazio 8y ago
  Why couldn't you use a heat pump to heat an insulated tank and get the same benefit?
- atoav 8y ago
  The problem is wind can be unreliable. With a electrical system you are way more flexible.You can use the generated electricity if you don’t need heat and if you are in the winter in a period without much wind you can fall back on solar or grid. Unless you live in an area with very steady wind during the winter and a more or less equal need for heat all year around, the electrical solution is more practical even if it is less efficient. I could imagine this for warm water with a different system used for heating or something like that.

VBprogrammer 8y ago

Whenever I read anything about wind turbines I'm reminded of this article. It's a shame the photos are missing at the moment. Maybe Jacques is around somewhere and can restore them. https://jacquesmattheij.com/how-to-build-a-windmill/ https://jacquesmattheij.com/how-to-build-a-windmill/

ashtonbaker 8y ago
The photos are working in the Wayback Machine: https://web.archive.org/web/20160813143636/http://www.jacquesmattheij.com/how-to-build-a-windmill https://web.archive.org/web/20160813143636/http://www.jacque...

golemiprague 8y ago

Heating water by the sun is very common in Israel since the 1950'. It is not working with solar panels but rather with a system that works more or less like this: Cold water is pumped (or flows by pressure) to the collector where the sun heats it. The heated water flows back to the collection tank. Since hot water is lighter than cold water, the heated water in the pipes moves up towards the tank, which sits at a higher level, and the cold water sinks from the tank to the bottom of the collector, creating a natural circulation cycle.

mark-r 8y ago

Can anyone explain to the ignorant among us (i.e. me) why converting to heat is so much more efficient than converting to electricity? The article makes the claim but doesn't back it up. What are the losses involved with each approach?

deleted 8y ago
[deleted]
bluGill 8y ago
Ultimately all approaches convert to heat with 100% efficiency. However the in between stages and what you do with the heat are in question. A Generator is 80-90% efficient in general, then you have battery charging losses (which I do not know), then battery discharge losses, finally, you have power transmission losses to get the electric around. All of the above losses are not captured. They are claiming that because everything is converted directly to heat near where it is used their total losses are less. (they assume insulation here) The losses in their system are gears (some of which exist in most generator systems), and tank losses over time. It is plausible they are right. However it all depends on local install factors which can be manipulated either way.
sleavey 8y ago
I think the main point the article was eluding to was that if you use wind power to first generate electricity then convert this into heat, you have two conversion steps with loss: wind to electricity, and then electricity to heat. The overall efficiency is then the product of the efficiencies of the two steps. If you produce heat directly from wind, you cut out one conversion with its associated inefficiency.
- mark-r 8y ago
  I always figured electricity to heat was nearly 100% efficient, it's the generating of electricity where the losses occur.

kristiandupont 8y ago

I've heard several times that electrical heaters of any kind are expensive and much less efficient than other heat sources and I feel like I am throwing money out of the window when I turn them on. This doesn't make any sense to me though. Can someone with a better understanding of physics than me explain to me why this would be the case? I would imagine electricity to be just about the most efficient way to transfer energy. And furthermore, as I understand it, lost energy tends to become heat!

dec0dedab0de 8y ago
Because in order to get the electricity to your house the power plant had to first do whatever it needed to do to generate the electricity. for example if the power plant is burning oil, and converting that to electricity, then you convert that electricity to heat you're going to get much less heat than just burning the oil yourself.
- dragonwriter 8y ago
  > for example if the power plant is burning oil, and converting that to electricity, then you convert that electricity to heat you're going to get much less heat than just burning the oil yourself. OTOH, the power plant probably has a rail connection or pipeline for oil, and the marginal energy cost of transporting an additional unit of oil to the power plant is probably quite low compared to the marginal energy cost of transporting the same additional unit of oil to your house.
  - dec0dedab0de 8y ago
    I'm not sure about that. I usually get about 125 gallons at a time. And since heating oil is just diesel with dye in it, we can just add deliver costs in gallons. Even assuming im the only delivery, I doubt it would take more than a gallon of gas to travel to my house. But to be safe lets say 5. With the above assumption, the question is Could 130 gallons burned at a power plant generate more heat in my house via electricity. Than 125 gallons burned in my house directly. I dont know enough to give an answer but my gut says no.

frankus 8y ago

I nearly flunked thermodynamics in college, so take this as the harebrained scheme/Burning Man hack that it would be. But I've wondered if you could get a useful amount of cooling/greywater disposal/hot clean water supply by mounting a wind-powered vacuum pump on top of a tall (11m +) column of water so that the water in the column would boil at ambient temperature.

tlb 8y ago
It turns out that water boils quite slowly at room temperature and low pressure, so you’d need a very large surface area.

netjiro 8y ago

Or, wind -> electricity -> heat pump (1:5) -> lots of heat?

ggm 8y ago

The obvious critique is that people in extreme poverty deserve every attention moment they can get, to derive a benefit with the lowest cost (to them) possible. But, when this represents an ad-hoc, it can often leave them stranded on a low increment from zero. So, adding proper drains to a favela is good because it reduces child mortality from bad drains, but its still a slum: the fix is unclear but probably involves a revolution. These mechanisms are good because they can be easily understood and whilst they will require patching and hacking and repair and are inefficient and can't do all things, if they can provide a stable heat source to remove the burden of burning things, which actually kills more women and children because of lack of oxygen, CO/CO2 poisoning, asthma and other effects, there is a huge positive upside. But, as has been said since at least the 1920s what we really need is soviet power, plus electricity.

aaron695 8y ago

Windmills are to noisy for cities (not necessarily it's claim) Large windmills have limits of ~300 meters from houses, not sure about small ones but unless you can cheaply get it to 5 meters, it's a fail. We know city noise kills, home windmills ramping up and down can't be good. It's have to be up there with cars and air conditioners / heat pumps. https://www.ge.com/reports/post/92442325225/how-loud-is-a-wind-turbine/ https://www.ge.com/reports/post/92442325225/how-loud-is-a-wi... Meh -https://www.theguardian.com/lifeandstyle/2018/jul/03/sonic-doom-noise-pollution-kills-heart-disease-diabetes https://www.theguardian.com/lifeandstyle/2018/jul/03/sonic-d...

QuamStiver 8y ago

I am curious about the potential for a hybrid wind turbine (clutchable): Generate electricity during peak hours (high price) / Generate storable heat during off-peak hours. Or would it be better to generate e-power all the time if the turbine is capable of it?

neilwilson 8y ago

Why do we keep trying to come up with ways to heat things when a human is a 100 watt heater at rest? Just insulate the building properly and then you can use rooftop solar to cool it down on those days when it gets too hot - largely because the sun is shining. Moving heat is generally easier than generating it.

speedplane 8y ago
Unless you live in a styrofoam box, you're going to need heating. Also, people like windows.
- neilwilson 8y ago
  PassivHaus standard can be warmed with a 1Kw heater at -10 degrees celsius. They have windows, doors and mechanical ventilation.
  - speedplane 8y ago
    I just read about Passive House, thanks for citing it. The standard requires less 15kWh/m^2 per year. I live in the U.S. in a 1200 sq ft apartment, small for U.S. standards, and that comes to ~4.5kwH per day. To put that in perspective, an 80 Watt computer running all day uses up nearly half of that margin. A small 6000 BTU A/C (good enough for a small bedroom) uses up the entire allowance if you run it for 8 hours in your bedroom while sleeping. An electric dryer will use up the entire allowance if you do two loads of clothing. I love that people are thinking about this, and I truly hope that it becomes standard, but it's not exactly reasonable for folks to expect such a level of efficiency without paying through the nose.
benj111 8y ago
This seems like a reasonable argument for wearing a jumper. I think you're firmly into diminishing returns if you're insulating your house to be warmed purely by body heat through the depths of winter. Plus what happens if you have a child? Do you remove insulation, run the AC through winter?

AltmousGadfly 8y ago

What I don't quite understand is: heat will be a byproduct of using electricity anyway, since it is always the waste product in the end. So why not generate electricity that can be put to good use first?

GrryDucape 8y ago

Another model could be to run an air compressor from the turbine. Compression will give you a heater, and then releasing the compressed air will give you cooling. Thinking about it some more, you should also be able to get kinetic energy out (or electricity) and water, by running a turbine on the compressed air and collecting moisture from the cooled air. Essentially one of these: https://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cycle#Gas_cycle https://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cy... - they're not technically as efficient as a phase change, but if it's simpler and there are fewer moving parts, it might be a win.

severak_cz 8y ago

The point of the article is that (unlike people would expect) THERE IS a direct way how to convert mechanical energy to heat. It can be even more effective (in theory) than heating via electricity from wind, because there is only one energy conversion (motion -> heat unlike motion -> electricity -> heat). Big downside is that heating with water brake is somewhat impractical and unexplored territory. However big plus of this approach is that you can make water brake with middle-age technology.