There doesn't appear to be anything new about this, ground-source heat pumps have been available for domestic use for quite some time.
And going by the name, and looks, it's actually an air-source heat-pump, but I could be wrong.
Ground source scales well if you have a large building and a large body of water near by then the payback time is short. But at single family home level it's just not that useful.
Further south solar systems have below your 5-10 year payback period.
There is a way: open-loop systems.
A few years ago we installed an open-loop ground source heat pump (ClimateMaster brand) for under $6k. Water at 50F is drawn from a preexisting 15 gpm/50 foot well, through the heat pump unit, then dumped in a dry well at around 40F. It uses half a million gallons of water a year (costing <$30 in electricity), but of course there's no aquifer depletion, and closed-loop systems also use energy to pump water. This unit also pre-warms hot water at its coefficient of performance (about "600%"), reducing electric DHW costs.
We homeowner installed, so we weren't eligible for NYS incentives. But it cut our annual bill in half vs. the previous heating oil furnace, with a payback period of 5-8 years.
Relative net savings depend on getting a system sized for your use, and how much cooling you use in the summer. But, you can also add solar panels for summer use with the overall value balancing over the year.
For clarity, my system provides both water heating and space heating/cooling.
It's basically "free" if your house needs a well anyway. (this assumes a lot about the ground under your house but it's relatively true ;P)
If you live in a mild climate, you are just not going see a lot of payback because as you said, you don't spend a lot.
Note: Most of them also provide hot water, not just heating and cooling
But all told, the path to making it popular would be to make it part of new construction. I understand why they want to try to make retrofitting cheap, but it's just not even close right now.
A typical water well drilling machine is on the back of a large truck and will bore a 30-40 cm hole for (prices here in Europe) 80-90 €/m.
There are smaller drill rigs (nothing that actually needs to be invented, only "normal" micropiling rigs) that can bore 10-20 cm diameter holes for a price of 60-70 Euro/m.
Let's say you need two holes 80 m deep, at 20 €/m difference (80-60=20 or 90-70=20):
28020=3,200
which represents roughly 10% of the actual price for the dandelion system (the real, not subsidized price) of 35,500 US$.
A typical small micropiling rig has a boring rate of around 100 or maybe 120 m per day so either they are really using a new, ultrafast technology (which I personally doubt) or are using less deep bores, and in any case the depth depends on the geology of the site, so everything is probably "averaged".
A geotermic pump with inverter with 20-30 kW of heating/refrigerating power should be around 15,000-18,000 € so, without more data 30,000 € or 35,000 US$ don't seem such a breakthrough (most probably they have huge savings due to the "massive" scale of operation, instead).
They're probably looking at a width of 10cm tops from their description.
As well the diameter of the bored hole implies a given diameter of the inner pipes, and they have obviously different thermal exchange capacity, though you can use smaller pipes using higher pressure in them.
Here there are some "generic" references (it is the site of an Italian firm that builds geothermal inverters, their English could be bettered):
http://en.rossatogroup.com/guide/pompe-di-calore/pompe-di-ca...
>Second, it has developed its own drilling rig–smaller and more nimble than traditional geothermal rigs. The custom-built machine is 19 feet long, 8 feet wide, and 8 feet tall, and weighs about 23,000 pounds compared to more than 70,000 pounds for a standard drilling rig. That means it can get closer to the house, and it won’t damage the grass so much, Hannun says.
Third, it drills a smaller hole–4.5 inches wide instead of a standard 6 inches. That means less dirt and rock coming out and less grout with which to fill the gap between the pipe and the ground. A six-inch hole produces 662 gallons of “spoils” and uses 561 gallons of grout to fill, Hannun says. A 4.5-inch one produces only 372 gallons of spoils and 271 gallons of grout–a 50% materials and spoils reduction. At the same time, Dandelion’s rig collects all the waste, so it’s not spread across the yard, Hannun says.
https://www.fastcompany.com/40440653/how-cheap-does-geotherm...
Unless the actual drilling technology has changed, it is nothing "new", an example of a "common" compact micropiling rig (also suitable for wells):
Even better if the existing geothermal and utility incumbents rise to the challenge and out-market and out-engineering naive Google to drive even greater adoption of sustainable tech!
I would take issue with their terminology though. To me, geothermal energy is extracting energy from hotspots in the earths's crust, as in Iceland, hot springs, and so on.
This is just using the stable temperatures below the surface as a source/sink for a heat-pump - no energy is being extracted. Hence ground-source heat-pump.
The advantage is that, while the outside air is almost always the wrong temperature (hot in the summer when your pump needs it to absorb heat, cold in the winter when you need to pull heat out of it), the ground is basically always the right temperature.
The disadvantage is install costs because you have to put piping underground by either trenching or drilling.
My sister outside of Pittsburgh, PA has had a https://www.waterfurnace.com for 17 years. Her system has paid for itself a few times over. She has 1500 ft of plastic tubing burried in her front yard.
Another fun thing made possible by geothermal: Some roads and sidewalks in Reykjavik are actually heated to prevent icing over.
(And before someone says it: Yes, Greenland is colder, but Iceland still gets pretty freaking cold. After walking two miles or so in an Icelandic blizzard once, I feel like I can claim some expertise on the subject.)