These are typically representative of cost performance per watt of one part of a more complex deployed energy system. Things like the aluminum / steal for the container / framing, copper / aluminum for the transmission and wiring, land and labor for installation decline at much less aggressive rates or increase over time.
In almost all pareto optimal least cost energy system models that I've seen, high penetration of solar, wind, batteries plus some minority amount of (clean) baseload power is the most capital efficient energy system.
The water at these temperature / depths has a lot of dissolved salts and minerals so it's not (human / ag) usable. Modern designs are closed loop systems where production wells bringing the hot water to the surface go through a heat exchanger to a different working fluid to drive the turbine and then is re-injected back into the reservoir. There is consumptive water use for fracking the reservoirs in these types of enhanced geothermal systems, but beyond that it's more water redistribution in the area around the well systems where re-injection and production lead to different pressurization from pumping / natural ground water replenishment rates.
Newberry Volcano is too good to be true in that there are few (outside of Yellowstone) equivalent sources of geothermal awesomeness at similar depths in the USA. Good for research bad for generalization of drilling costs to hit similar temperatures. There are federal protections for geothermal drilling anywhere near Yellowstone.
It does work technically I think it is still an open question if it can work economically. There are issues of commercially viable flow rates / thermal decline rates that are harder physical limits you run up against and the pilot design doesn't address. In human timescale terms it's more like heat mining rather than renewable heat due to thermal depletion rate vs replenishment rate. These systems have a targeted lifetime of ~20-30 years and net power will decline over this timespan.
The core breakthroughs were working with partners to develop PDC bits that enable high rates of penetration in drilling out these horizontal wells in high temp granitic rock and then demonstrating plug / perf fracture networks that have a high engineered permeability in these source rocks to support economical flow rates and heat transfer. These were considerable advances over previous efforts.
There will be other learning by doing advances in how you structure your power plant design to take advantage of these to make practical long term power production possible (well spacing and injection / production placement / flow rate and temperature decline management).
In traditional fault hosted (not magmatic) geothermal the convection of the water up the fault brings the thermal energy closer to the surface where drilling depths are economical. This convection heats the surrounding rock and over hundred thousand - million of years brings the background temperature around a large volume at depth surrounding these systems considerably above traditional background geothermal gradients. By drilling into a much larger volume of impermeable hot rock surrounding a very small permeable fault hosted section you can considerably enhance the power potential of a traditional fault hosted geothermal system (the E in EGS). That is what Fervo is doing and why their projects are situated right next to traditional geothermal power plants.
The assumption is that if you can increase drilling efficiencies enough then you don't even need a fault hosted or similar system to bring that energy close to the surface, you can just drill down deep enough to get at similar temperatures. That is a big assumption in the economics.
Fervo uses engineered reservoirs in granitic basement rock so this is less of an issue. Hot rock in a working fluid can still dissolve silicates out of the granite and lead to scaling / degradation of the flow rates through the reservoir and that is a risk but chemical anti scaling treatments are used to reduce this.
CA has the worlds largest geothermal power complex in the Geysers. That one field produces an equivalent amount of power as all the geothermal in Iceland and there are others.
In geothermal there is still a lot of interest in efficiency and exploring different working fluids because binary systems now have efficiencies of 10-20%. That is why you see companies like Sage Geosystems working on developing / deploying supercritical CO2 turbines to try and boost practical power densities.
There is no way to tell yet what the longevity of the resource will be as it's too early. In fracked resources the main issue is "short circuiting" where increased flow rates travel along preferential paths between the doublet wells as the source rock cools and cooling rate of the source rock in general. This causes the MWt of the resource to decline per injection / production well. Fervo is getting around this by drilling extra wells per pad to be turned on in response. Many geothermal resources decline over time as heat is slowly extracted and these declines are somewhat manageable by tuning the injection production well rates and drilling new wells. They are built into the economics of existing plants. Geothermal is kind of extractive and not "renewable" in this way over medium term time scales, you need to continuously keep drilling at a certain rate. Rock is a good insulator and it takes a long, long time for it to heat back up.
You are right there is no getting around that relatively low grade heat in geothermal is a big barrier for scaling in terms of energy production. Binary /organic rankine cycle geothermal plants used for these low / medium temperature resources operate at ~10% efficiency. Dry / flash steam resources are higher but produce waste in terms of emitted GHG and / or crap in the geothermal brine.
Deep geothermal promises to provide what is usually considered high-grade heat (800+°), but what I'm trying to understand is how cheaply you can convert that high-grade heat into electricity, because the answer seems to be "far too expensively to be competitive with wind and solar".
Supercritical geothermal is similar to talking about the economics of fusion. There is a DOE enhanced geothermal test site near the Newberry Volcano in central Oregon which has temperatures close to this range at reachable depths. That is more of a demonstration site for drilling technology.
Yes, but if (as I am claiming) there's no way to economically turn heat into electricity, it's irrelevant whether supercritical geothermal steam costs trillions of dollars per borehole or is free; either way it's uneconomic as a source of electricity.
In almost all pareto optimal least cost energy system models that I've seen, high penetration of solar, wind, batteries plus some minority amount of (clean) baseload power is the most capital efficient energy system.
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