Comment by andruschakartem
10 hours ago
23 months to build is impressive, but the number that matters for EGS is thermal drawdown. If the fractured rock cools faster than modeled they have to keep drilling new wells, so I'd like to see Cape's output a few years in.
Fervo engineers for thermal drawdown up front, it is well known that for EGS to maintain constant power output you need to periodically re-stimulate the field after a period of some number of years. What matters for the economics is the rate of eventual drawdown. The nameplate 100MW is also a bit misleading as it represents gross power output without taking into account the parasitic load of pumping which for an EGS plant is quite high. There was a ~60% parasitic load for their test facility and IIRC Fervo is eventually targeting 30-40% for the commercial power plant.
Would the deep-drilling approach enabled by Quaise alleviate this issue ?? I was super-interested when Quiase was first announced, but not sure if they are moving towards viability. Insights appreciated. Thx, NSC
Not really, it is more the limiting physics of extracting heat through conductive transfer in the rock. The rate of heat extraction through fluid convection has to be less than the rate of conductive replenishment though the basement rock to not get thermal drawdown and these rates are often not economical.
Is there any reason to believe this is likely?
If it wasn't, enhanced geothermal would be everywhere, which it isn't. (Yet, this company would say.)
Op is really just describing a core breakeven metric on the energy source. In the same way you measure an oil well with half-life of useful output, this is basically saying "EGS can prove to be useful if they can make sure they extract more economically useful heat than the economic costs of constantly drilling new wells."
Since no one has really made EGS widespread yet, that suggests no one has yet cracked this nut.
> If it wasn't, enhanced geothermal would be everywhere, which it isn't.
That seems like a fallacy.
4 replies →
It is not an uncommon problem with geothermal.