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Comment by iancmceachern | Hacker News Reader

Make drilling cheaper. This would also help with water access. The biggest cost of small geothermal and water projects is always the drilling. Drill rig time is always a limiting factor.

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Drilling is supposed to get cheaper when it is done with microwaves instead of drill bits.

But the expense of maintaining the necessary steam turbine still makes it hard for geo to compete with wind and solar. This is also a major factor in the cost of operating a nuke plant, with similar effect on competitiveness. Really big steam turbines cost less to keep than a lot of small ones, but then you generally need to build two so you have a backup when one is down for maintenance.

TIL proposals to drill with microwaves [0].

In summary, a (dumb yet durable) metal waveguide+pipe stretches down, it emits microwaves to vaporize the rock face, and gas pumped down through it is released so that it exhausts back up along with the removed mass of rock-vapor/particles.

> [P]roducing the supercritical steam needed requires drilling to depths of 10 to 20 km [...] rock is capable of both producing superheated steam and destroying the microchips and seals required for directional drilling.

[0] https://jpt.spe.org/microwave-drilling-sounds-like-science-f...

That's about Quaise Energy, which have been on HN many times in the recent past.

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

I was hopeful that all of the unused drilling capacity after the shale boom/bust would allow some of the know how and equipment to be reallocated to geothermal but the grid operators and markets are not offering the premium to firm capacity that is required for the longer lead time and increased capital requirements and increased risk in geothermal projects vs wind and solar which can be augmented with battery storage.

It’s going to suck though when we hit a weeklong stretch of cloudy still weather if there isn’t enough spare capacity from other sources to compensate for the missing wind and solar.

> if there isn’t enough spare capacity from other sources to compensate for the missing wind and solar

This seems like a problem Elon would gladly dabble in, pushing out a NACS firmware update or something as an emergency limiter. Maybe first responders get priority, like they do for mobile network congestion.

Or dirtier power remains on cold standby for unusual peaks. This would eventually be outlawed, I imagine.

For week long storage there is always hydrogen, if alternative battery chemistries don’t pan out.

Hydrogen conversion is not only very inefficient, the hydrogen plants are also extremely costly.

Batteries are better bet.

Only for short term storage. Hydrogen is meant for longer term storage where batteries have too high of a losses. E.g. winter vs summer.

Way way way cheaper to 10x overbuild renewables than produce (and store) hydrogen at that scale.

It's actually not. There's a reason there are a lot of hydrogen storage projects for electricity generation going on.

Hydrogen is even better for longer-term storage (e.g. seasonal). Produce hydrogen via electrolysis from solar in the summer, then power things when it's cloudy + low sun angle in the winter. There are quite a few major hydrogen storage projects in progress that do exactly that, FWIW. E.g. https://www.energy.gov/lpo/advanced-clean-energy-storage (Disclaimer: My wife works on that project)

Batteries don't compete for long term storage. Losses are too high. Hydrogen is an excellent solution for longer term (weeks to months to years) storage.

I'm trying to imagine the apocalyptic scenario that'd have all of Texas windless and cloudy for a week? Nameplate values for Texas wind & solar will eventually be well above peak required: excess power can be sold for silly things like bitcoin, desalination, fabbing, etc.

Right now wind is running at 16% capacity producing 6GW; you'd need ~308GW capacity to cover Texas needs from wind alone. Good luck.

That is why there is also solar

And there is also night. And clouds. Texas is good for solar but December and January still have relatively high variance - for example, in December 13 solar produced only 19.3 GWh while it produced 103 GWh two weeks later on December 27.

No single source has ever provided all electricity for any major region. To pretend otherwise is disingenuous.

Fossil fuels have done that trick, long before gridscale wind and solar ever existed.

So really you're the one being disingenuous.

Fossil Fuels aren't all one thing. There are different types, with vastly different infrastructures, etc.

Coal is not natural gas

Winter Storm Uri came pretty close to that. Very overcast every day. Pretty low wind compared to normal. I'm not blaming wind or solar for the failures; it was largely failures in gas production. But solar and wind output weren't close to their nameplate capacity.

Bitcoin sounds like the absolute worst thing to buy with excess electrical production. But desalination sounds like an excellent thing to buy. Silly is not the word I'd use.

The best thing to buy is just battery energy storage (or molten salt or hydro-pumped). Storage prices are falling even faster than the solar PV modules themselves, and there are dozens of huge factories being built every year, in the USA as well.

It seems like desalination is discussed on HN frequently but I have yet to see tech that makes any financial sense, even with somewhat cheaper power.

I wonder if geothermal can offer mild battery storage by using excess energy to pre-heat the water.

Yes, though its not geothermal preciously - https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community

> The Drake Landing Solar Community (DLSC) is a planned community in Okotoks, Alberta, Canada, equipped with a central solar heating system and other energy efficient technologies.

> In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span.

> In 2015–2016 season the installation achieved a solar fraction of 100%. This was achieved by the borehole thermal storage system (BTES) finally reaching high temperature after years of charging, as well as improving control methods, operating pumps at lower speed most of the time, reducing extra energy need as well using weather forecasts to optimize transfer of heat between different storage tanks and loops. During some other years, auxiliary gas heaters are used for a small fraction of the year to provide heat to a district loop. The systems operate at coefficient of performance of 30.

https://www.dlsc.ca

https://www.sciencedirect.com/topics/engineering/drake-landi...

http://proceedings.ises.org/paper/swc2017/swc2017-0033-Mesqu...

I don't know about directly as a battery, but there is potential for energy storage. If you have geothermal HVAC at home, it can (sometimes) be use to heat water in a water heater. Dumping the extra heat into it. And I have heard stuff about using excess energy in the grid to put extra heat into home water tanks as well, so demand is reduced later. It is not getting converted back to electricity, but still a store for energy.

I don’t think thermodynamics lets that work. You can’t move heat from something cold to something hot so unless you are preheating your water to a temperature higher than your deep borehole rocks, all you’re doing is putting the first N joules of heat energy into the water you’re going to pump into your steam turbines using excess grid energy instead of geothermal energy.

Of course you can move heat from something hot to something cold, it’s called a heat pump. Though yeah I get what you meant. There are heat pumps that have entered production that are designed to generate the kind of industrial levels of heat required to heat the water to the level required to add heat to such reservoirs. Whether it makes sense, I can’t say. But it certainly makes sense for geothermal well used for district heating (not electricity). It’s already being done.

Funny thought: if you use a heat pump to store heat energy in summer to be used in winter.. and your reservoir can retain the heat efficiently (think the heavily insulated sand reservoir used in a project in Finland for instance)… could that make the battery effectively more than 100% efficient?

"Lisa! In this house we obey the laws of thermodynamics!" - Homer

This is how Fervo Energy was founded. https://fervoenergy.com

Yeah. We'd do 3"-6" wells at 450ft for hvac geo and it'd be 10%-30% of the project cost. I don't believe drilling has gotten cheaper in my lifetime.

We just recently got Geo HVAC, for our two units it was 800 total feet divided into 2 wells. And drilling was in the area of 25% of the total cost. 50% for the units themselves, and I guess 25% for the other parts, labor, and misc stuff.

While drilling is definitely a big chunk, all of it is so much more expensive than traditional air heat pumps that even without drilling it would still be at least 50% more expensive. Double without US Federal incentives.

> Make drilling cheaper.

How?

I've been wanting to build and try something like this:

https://youtu.be/3pOSzBgB8WU?si=kCyDZA0GkKMFAzNH

Could easily be improved upon, seems workable

For shallow dirt holes, sure.

Not so great once the pressure increases or granite|schist layer intercede.

I've been thinking one could add a water powered bit on the tip not unlike the tips they have on more traditional drill rigs. I think there is lots of room for improvement on this technique, lots of white space between this and a traditional rig.

For the purposes talked about in the linked article they're not really looking for new tech that lies between a traditional mining drill and a garden hose though - they're looking beyond the capabilities of traditional mining drill:

     Commercial drilling doesn’t usually go much deeper than seven kilometers (four miles)—for cost reasons, it’s often even less than that—and many places that might benefit from geothermal aren’t hot enough at that depth to reach the 150 °C needed to generate electricity economically.

    Reaching sufficient temperatures may mean going deeper, which would require new techniques and technologies that can withstand high heat and pressure.

Yeah, I'm not bounding my thinking, and future plans, by this article.

I was just mentioning that something I've been thinking of was similar.

we can power it with free geothermal! the deeper the hole gets, the faster the drilling goes. it's power all the way down!

Power's not the issue, labor is. Untill you can replace roughnecks with robots, it's not likely to change.

with all the free power we could give the roughnecks all the juice they need to mine bitcoin... while they are at work

Agreed: how? Drilling companies have been competing on price for a hundred years; anyone who came up with a significantly cheaper drilling system would be raking in the dough until everyone else caught up.

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