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Well, that is what they say (without telling anything about the actual drilling method). A typical water well drilling machine is on the back of a large truck
by jaclaz 8y ago
Well, that is what they say (without telling anything about the actual drilling method).
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).
- raverbashing 8y agoDoes it really need to go 80m deep? Seems like a very deep hole They're probably looking at a width of 10cm tops from their description.
- jaclaz 8y agoIt depends on the geology underneath (I have no idea what is under the area they are currently covering) the amount of heat exchange can vary a lot, even within the same type of soil/rock. 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-calore-geotermiche/126-come-realizzare-un-impianto-geotermico-con-pozzi-verticali.html http://en.rossatogroup.com/guide/pompe-di-calore/pompe-di-ca...
- raverbashing 8y agoThanks, that explains it well!
- jaclaz 8y agoReplying to myself, to add some actual data for the drilling rig from another source: >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-geothermal-need-to-be-before-it-becomes-the-next-solar 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): http://www.massenzarigs.com/company/drilling-rig-mi4 http://www.massenzarigs.com/company/drilling-rig-mi4