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Comment by danpalmer | Hacker News Reader

Thank you for this, lots to be optimistic about! Forgive my ignorance, but...

> They expect to be able to combine this with solar/wind to get a firm 24 hour renewable base load.

Why would they need solar/wind to get a renewable base load? I know solar/wind can't provide that base load by themselves (at least not in one region), but I expected that geothermal would basically be constant, or at least fluctuate by only small percentages throughout a day? Does solar/wind really bring anything to the table in terms of base load here, or is it just that geothermal would provide the base load and solar/wind could be used for seasonal usage on top?

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Geothermal heat reservoirs are renewable but not unlimited: heat is taken out of the rock by the working fluid and results in "thermal drawdown" until heat is conducted from adjacent areas. I would assume this is worse for hot dry rock enhanced geothermal systems like this one, where you don't have hydrothermal circulation moving hot water through the reservoir. Just for some graphs: https://www.osti.gov/servlets/purl/888907 . So perhaps only running your geothermal plant at night extends the lifespan of your well.

> Why would they need solar/wind to get a renewable base load? I know solar/wind can't provide that base load by themselves (at least not in one region), but I expected that geothermal would basically be constant, or at least fluctuate by only small percentages throughout a day? Does solar/wind really bring anything to the table in terms of base load here, or is it just that geothermal would provide the base load and solar/wind could be used for seasonal usage on top?

Think of geothermal as being a drop-in replacement for natural gas turbines today. On wind/solar heavy grids, natural gas turbines spin up when wind/solar go down. The most reliable returns on investment in geothermal will come from targeting gas turbines, because that will result in maximizing the utilization of the geothermal system. Building geothermal capacity to meet variable demand is very expensive. Relatively to that, building solar/wind is not.

Utility solar and onshore wind on the other hand are incredibly cheap, especially when you don't have to store the energy. At this moment (~09:45 PDT on November 28, 2023), solar and wind are providing 61% of electric demand in California, with no storage involved [1].

In the case that geothermal starts taking over baseload from natural gas and nuclear, wind and solar will continue their downward price trend and still be favored when their supply and demand are time-correlated, and will also be used for very dispatchable end-uses (i.e. EV charging, water heating).

They will also be coupled with storage to provide demand-following peaker resources (since batteries can respond extremely quickly to demand spikes).

If geothermal gets so cheap that there is little difference in price between it and solar/wind+storage, then it will probably indeed take over a lot of current wind/solar demand, but ever increasing demand from variable loads will continue to soak up wind/solar supply, especially as the transition away from fossil fuels accelerates.

Finally, geothermal has much higher upfront/fixed costs (due to the necessity of drilling and the machinery for the turbine), so while better than nuclear, it's still harder to use for distributed generation than solar. Distributed generation (especially behind the meter) provides resilience to distribution outages.

1. https://www.caiso.com/TodaysOutlook/Pages/supply.aspx

IIRC there have been some experiments with using geothermal plants as peaker plants since you can pump more water down and cap the output so you can ramp output up quickly later. This could work well with the variability of renewables to help balance out the grid, a role traditionally held by coal / gas.

https://www.volts.wtf/p/enhanced-geothermal-power-is-finally

I believe wind/solar are still cheaper than geothermal. They'll be priorities #1 and #2, with geothermal to make up any difference.

edit: and when the sun isn't shining and wind isn't blowing

Base load is an obsolete concept that nobody needs at all. It applies to some coal and nuclear power plants that take days to startup and cannot throttle back. You accepted this because they are very cheap to run.

Renewables have their issues, but they are different than base load.

Let me rephrase - 'constant output 24/7/365 renewable power'

Base load is decidedly not an obsolete concept. Renewables go to zero, and building sufficient peaking capacity to overcome a total loss of grid power would be preposterously expensive. Renewables spread over a large enough geography could, hypothetically, overcome variability, but nowhere in the world has developed the grid capacity (or even renewable generation capacity) to substantiate that strategy, and the odds of the US developing that kind of grid capacity are nil. There will always be a need for substantial base load generation.

What you described is NOT what baseload is about though.

Once again, baseload refers to power plants that deliver exactly the same power 24x7, but only after a couple week startup process. That is not what renewables deliver. It is in fact worthless with renewables because when renewables are at their peak time of day they already provide 100% of power and baseload forces more power on top of that.

Canadian uppercase hello here!

...Here's your baseload: https://energyeducation.ca/encyclopedia/Baseload_power#:~:te....

Also, I guess: what in your mind is the difference between what baseload is, and what baseload is about?

Baseload is a useless concept except in the context of coal powerplants that don't exist. Anything modern either follows the load without problems or has an unpredictable nature that means you don't care about averages.

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