Geothermal Hyperloop
I’ve read about geothermal on this site and understand the downsides of the incredibly high installation costs. However, I just recently came across some info on hyperloops – which are supposed to take up much less space than conventional horizontal closed loop systems. Has anyone had any experience with one of these systems? Do they offer any significant break in terms of lower install costs? Are they more fragile or any less dependable or efficient? Here’s a video I found that describes what it is:
Also, I saw another video (linked below) of someone installing a hyperloop in a river. I had a question for my dad who is building a house in Northen Michigan on the Black River. Are there any potential headaches to installing such a system in a public river like this? Are there efficiency issues with the water temps especially in the winter? What about doing an open source pump and dump into the river? Any thoughts would be appreciated. Thanks.
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Brian,
"Hyperloop" seems to be a brand name for a plastic manifold system -- a way of squeezing lots of small-diameter plastic pipes into a small area.
It's not revolutionary -- and I don't think it changes the fundamental disadvantages of ground-source heat pumps. Remember, the big cost of these systems is the equipment inside your home, not the loops in your yard. For more information, see Are Affordable Ground-Source Heat Pumps On the Horizon?
Brian-I'd be surprised if anyone can just install something in a federally regulated river (which is just about every river, stream, or brook in the country) without all sorts of permits. Dumping anything in the river, even water that has run through the heat pump, would probably require a permit which would not just be a regular Clean Water Act permit, which are pretty easy to get. The effluent water would often be hotter or colder than the river water, which could impact aquatic life.
The river water in winter would probably be pretty cold in Northern Michigan in winter, close to freezing< which would have a negative impact on the efficiency of the heat pump. The big supposed benefit to GSHP is that in winter they take advantage of the relatively warm earth several feet below the surface.
The only Hyperloop I've heard of is Elon Musk's plan to transport people through a big pneumatic tube.
Like anything else, to operate effectively & efficiently the system has to be designed correctly for the loads and conditions, and it's not particularly amenable to DIY design, and COMPLETLELY out of the realm of "design by web-forum".
The Waterfurnace Hyperloop is basically a gloried swimming-pool solar collector re-purposed/re-designed to be buried. This was a popular sort of hack amongst tinkerers a decade or so ago, and I'm not surprised that somebody made a commercial product out of it.
t would work better in a pond than in the dirt. The specific heat of ice is about half that of liquid water, so once it the body of water freezes solid the efficiency goes to hell as the loop temps plummet at 2x the rate. But the heat of fusion of water is HUGE when operating near the freezing point, and that give pond-loops and rivers a significant advantage over buried trench loops. The heat transfer from water or ice to tubing is far more efficient compared to dirt in your backyard trench, so the amount of tubing required is less than with buried ground loop approaches. If used in a pond you want to be sure it's deep enough in the water that it is placed well below the natural ice depth.
Open loop systems in rivers would be prone to all sorts of issues- only for the brave of wallet.
The makers of this product (Teva Energy) seem to be primarily promoting it for pond use, with inserting it in a trench as an afterthought. Their page on the trench installation they specifically warn that they don't enough information to recommend any specific sizing guidelines, which to me means they don't any basis for claiming that it has any advantage over any other design. It looks to me like it would offer a large surface area such that the thermal resistance between the fluid and the ground would be low compared to a conventional design with the same length trench. That might seem to indicate that you could save money by using a shorter trench. But if you used a shorter trench, the smaller volume of earth that you'd be accessing would be too small and so the heat in it would quickly get depleted. I think they started with a solar collector technology and wondered whether they could use it for this application, rather than engineering a superior ground loop system.
For ponds, there are many site-built designs as well as a few products out there that can be used to simply and inexpensively make a pond heat exchanger. This might perform similarly. It looks like it might be less robust. But any pond system is already pretty inexpensive to install compared to trenching or drilling wells, so even if this offers better performance per dollar and is robust, it won't move the needle on overall system cost or performance.