> 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
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.
> "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.
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.
> 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.
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.
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.
So many neat articles on that site - the obsolete section is particularly great.
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.
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.
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.
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.
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.
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.
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.
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.
Driving a heat pump mechanically with a microhydro system would be interesting.
More consistent energy output paired with easy storage.
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.
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.
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.
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.
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?
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!
well while we are on the topic of heating i am still surprised 'data furnaces' have not been adopted more.
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.
> 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.