Apple patent app describes storing rotational wind energy via heat in new on-demand electricity generator

“Last month we reported on Apple and Google being the top tech leaders in harnessing solar energy,” Jack Purcher reports for Patently Apple.

“In a new patent application published by the US Patent Office this morning, we discover that Apple has invented a new on-demand system to harness stored wind energy,” Purcher reports. “More specifically, Apple’s patent relates to techniques for storing rotational energy from a wind turbine as heat and using the stored heat to subsequently generate electricity on demand.”

“Apple’s invention provides a system that generates electricity. During operation, the system uses a set of rotating blades to convert rotational energy from a wind turbine into heat in a low-heat-capacity fluid,” Purcher reports. “Next, the system selectively transfers the heat from the low-heat-capacity fluid to a working fluid. Finally, the system uses the transferred heat in the working fluid to generate electricity.”

More info, including Apple’s patent application illustrations and diagrams, in the full article here.


  1. Motion to Heat->Heat to Motion->Motion to Electricity. Surely too many conversions and hence too many inefficiencies. Not to mention all that thermal cladding to keep the heat in. Why not just MOTION to ELECTRICITY (Batteries) and be done? Not that I know better than Apple, but nevertheless confusing.

          1. There’s nothing dumb about Tjk’s statement. Wouldn’t you assume that Apple would have thought through their innovation enough to know whether it had any merit? Wouldn’t you also assume that your 2-minute read and a post on the subject probably misses some key concepts in the process?

            The reality is that you’ve oversimplified the process of converting motion to electricity, and then jumped to the conclusion that any other way seems inefficient. The problem is that converting motion to AC current, converting that AC current to DC current to charge batteries, then inverting the battery output to make on-demand AC electricity is EXTREMELY inefficient.

            Worse, because of the size and number of batteries that would need to be involved, it’s physically impossible to do on any large scale, and even if it were, batteries are an ecological nightmare.

            Batteries are terrible storage devices for energy storage on a large scale like this patent represents, so the comparison is invalid from the start.

            1. “….Wouldn’t you assume that Apple would have thought through their innovation enough to know whether it had any merit?….

              Actually I did. If only you had read my last sentence. Nevermind. Here….You have the smart-alec medal. Happy now!

          2. Paul,

            You should relax.

            By my estimation, this method of storing heat is efficient and not relying on batteries. In addition, energy could still be generated when there is no wind.

            This isn’t designed to be a sole energy source but rather to support power plants and cut costs.

            1. I am quite relaxed. Thank you. Just trying to contribute in my relaxed way as best I can. Trying to ask questions. Trying to wonder. Trying to correct misunderstandings. Etc Etc.

              For example, you seem to misunderstand that energy might not be available when there was no wind. Let me just correct you on that…not that I want to because I somehow want to sneer at you etc…..but just because of progress/discussion. So relax, nothing personal.

              Stored energy can be accessed. Even when there is no wind. This is true for battery storage as well as thermal storage. And yes, I fully realize it is supplemental. That was never in question.

              Now let me offer to you what I have learned today……other than the fact that a simple musing on an idea can cause such a ruckus on this board. I have learned (from other contributors on this thread) that battery storage may not be as good as thermal storage. I found that quite educational and thank all those that pointed that out.

            2. Paul, you are correct that there are losses in any type of energy conversion. The quality of the stored thermal energy is a key consideration in terms of efficiency in converting it to electrical energy. The snarky comments from ignorati like Tjk are unwarranted.

              I’ll keep an eye on this technique. I am not willing to assume that it represents a major breakthrough in energy technology just because the patent submission came from Apple. The patent office does not measure the relative merit of submissions – there are plenty of patents that offer little value, such as the mechanical hat tipper.

    1. Batteries need replacing every so often, perhaps apple has found a greener way, though less efficient. My only thought was wouldnt using the sunlight to grab heat be much better, you can concentrate it and create alot of heat. But I’m sure that already is patented, whereas this method probably isn’t.

    2. Batteries are inefficient too. Plus they’re expensive, bad for the environment and have a short useful life.

      If someone (Apple?) can find a way to store large amounts of solar and wind generated energy for 12 or more hours, they will have solved one of the largest issues holding these renewables back.

      Without an industrial-scale storage mechanism, solar and wind are essentially relegated to smoothing out peaks in demand when available. Without a way to store solar & wind energy, we’ll always need coal (or much preferably natural gas) for baseload generation.

      We have to seriously start phasing out coal, but we can’t build more hydro, and people are still luke-warm on nuclear.

      1. There have been some good studies on providing 100% of baseline power via renewables with 99.9% availability (modest fossil fuel backups needed to smooth the bumps, just as with the current power grid). I believe that ars technica carried an article on this topic a few weeks ago. People tend to be too pessimistic with respect to wind, solar, hydro, and wave/current power. The existing energy industry has done a tremendous job of injecting money into the system to generate widespread public doubt. Consider the stakes – tens of billions of barrels of reserves representing huge future revenues and profits…if the demand is maintained or increased. We use fossil fuels for many things – burning huge quantities for transportation and electrical energy is wasteful when there are viable alternatives that can be blended into a diversified energy structure.

    3. The big problem with wind-power is storage. Wind isn’t constant, so you need to storage excess generated energy to use when the wind ain’t blowing. I’m no engineer, so I have no idea about the viability of this system, but that is the issue Apple are trying to address.

      1. The best way to store wind power is not to store it at all but to use it immediately by putting it on the grid and reduce the need for other producers. If the whole continent put wind energy on the grid, there would be a nearly constant supply and coal plants would only be needed to supply peak demand.

    4. Paul, if this innovation is used in the Apple data centers, then the heat produced by wind turbines could be used to augment the heat pumps that already exist. Heat waste is one of the larger problems that data centers face and is typically solved by installing large and complex A/C units and liquid cooling systems. If apple can use the waste heat to provide power then they really do have an innovation worth developing and protecting.

    5. Generally true but what you are missing is that once a well insulated heat reservoir has reached a nominal working/productive temperature, the efficiency increases and the costs to maintain that optimal temperature are relatively tiny for both input and energy harvesting.
      There are huge efficiencies to be made at various points of the system and I suspect Apple has identified some of these. We upgraded our domestic heat pump with a new pressurised unit and immediately realised a benefit from reduced pump activity/power usage.

    6. I used to live near Altamont Pass in Ca which has had a large number of wind turbines since the 80s. US WIndpower used to own/manage many of the turbines and they’d do PR/educational talks at the local highschools. Invariably folks would ask why so many windmills were not operating.

      It turns out wind turbines can only generate electricity within a vary narrow band of wind velocity. That’s why they have complex breaking/transmission systems (they also require a lot of maintenance).

      Finding a way to store the energy generated by a larger windspeed bandwidth while also physically decoupling generator from the turbine would result in more efficient energy production,reduced wear/tear on equipment. Maybe that’s what the patent tries to address? (I’m too lazy to look at it).

    7. Nuclear fission to heat, heat to water, water to steam, steam under pressure to turbine, turbine generates electricity.

      Start with coal and follow the same recipe.

      Obviously, a heat source can create electricity.

  2. Probably because electrical storage is a) expensive, b) lossy, and c) requires batteries being replaced (ongoing expense). A system like this isn’t particularly efficient, but it’s more efficient in the long term than going straight to batteries.

    The idea is to store wind energy, a rather tricky thing to do. Wind energy generated in the US is usually supplemental to coal/gas/nuclear power since it cannot be relied upon to be 100% constant.

  3. Actually storing wind energy is easy – the tricky bit is to achieve fast switch over times (from storing to extracting when demand exceeds supply). For that you need millisecond reactivity. Surprisingly there is a cheap, effective, and fast way to do it – store it as pressurised air.

  4. To me, the upshot of the story is that it is heartening that , the most innovative company on the planet, is addressing possible solutions to create alternative energy sources that could be sold to individual households. Pretty neat. I’d love to tell my electric company to go fuck themselves. Wish they would also R&D a car.

  5. ok, as long as there isn’t some subsidy hidden in the cost mix that makes it appear to contradict the laws of reality, which cannot be broken by anyone even if we take a poll that says we can.

    Thats where wind is right now.

  6. Actually heat is a huge problem in power production. Two thirds is lost as heat and the last third is actual usable power. Since I do not know the heat to power ratio a large scale wind generator, would assume similar to standard power plant. So, a one megawatt windmill will likely waste two megawatts of waste heat. If you find a way to store that amount of heat for later use, of course with converted loss, you could create a large efficiency increase in windmill tech.

    Looks as if Apple is address a similar problem with their data centers and as such could be used in windmill power generation. Even power plants are testing methods of using waste heat to grow algae to process as an oi replacement. Apple again seems to be looking at reducing waste. This time it is heat wasted in the process and heat is very easy to create in mechanical systems.

  7. Guys, this is a patent application. It may never issue.

    You have to read the claims and compare to other existing patents to get an idea of whether the claims are likely to issue. Lots of claims get tossed out.

    If Apple achieves only minor claims on issuance, they may have no practical value to the patent.

  8. There’s a lot of discussion about the efficiency of the approach described in Apple’s patent. What people seem to be missing is that this Research and Development work can lead to other breakthrough related or completely unrelated to the actual patent. Through such experimentation, new laws are learned that can be applied in new ways. This particular approach may never be used, but aspects of it may contribute to other innovations. That’s the point of R&D.

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