A big bet on geothermal could help prevent a climate catastrophe
homerdixon.com
homerdixon.com
Plasma drilling sounds like it could be useful - the plasma essentially melts the material surrounding the borehole into a glass as it drills down.
We nearly tripled the square footage but our total energy costs stayed almost exactly the same.
Went from gas heat/electric cooling to all electric geothermal. We still have natural gas for a backup generator, cooking and laundry dryer. We kept gas for kitchen/washing because there's a monthly minimum for gas service that we'd use for the generator. DC's Pepco power is notoriously unreliable.
Near-surface geothermal seems a better investment, if you have room for it.
A purely selfish side-effect is NO NOISE from outdoor condenser fans. Three of them necessary would have wasted a lot of space too, and been more maintenance items.
Near surface only works if you've got a lot of square footage to spread it out. The average suburban lot would not have the space for it (I thought that would have been obvious).
We might need to retroname the old one... Geosteam? Borehole?
Maybe a closed-cycle nitrogen or helium turbine would make for fewer overhauls, thus lower maintenance cost, vs. exposing your turbines to superheated steam all the live-long day.
Generation can be divided in several ways.
There are vapour and fluid-dominant systems, which refer to the dominant phase of the heat-transer fluid (water in all cases I'm aware), that is, liquid or steam. I'm not aware of any gas-based heat transfer, though you might want to add CO2 to your list as a potential working fluid. The phase-transition of steam from hot to cold side achieves much of the delivered power, and you'd be missing out on this with a purely gaseous medium.
There are also both naturally occurring and enhanced sites. The former employ some existing geothermal site on Earth's surface, typically geysers or volcano. The latter can be sited anywhere, using a borehole. The difference being that drilling is far more expensive than tapping into an existing near-surface structure. The system Homer-Dixon is describing is a very deep borehole --- tens of kilometers rather than a few thousand meters.
Geothermal heating utilises the direct thermal potential of the ground, rather than generating electricity (or as an adjunct to having generated electricity). These concepts range from existing / opportunistic siting such as hot springs or hot baths, to technically-coupled heat transfer and/or storage through heat pumps with a ground-loop component.
There are also passive designs which simply utilise the insulating capabilities of soil or bedrock. Thick-walled adobe or stone structures thermoregulate by sheer thermal mass (possibly with other elements to increase or reduce solar gain and airflow). Sub-grade, semi-underground, or backfilled structures operate similarly. Seasonal thermal energy storage may be incorporated into single structures or at a community level in which excess summer heat is transferred to a thermally-stable geographic strata, and recovered from the same in winter. This requires that the subterranian layer not have a substantial heat flow, e.g., groundwater which would convey stored heat or cold away.
There are also structures which exhibit an unwanted thermal effect over time. Many deep mines are hot and require active cooling of airflows. The London Underground subway system runs through rock strata which have absorbed heat from equipment and passengers for over a century, and whilst initially cool, is now unpleasantly warm. Plans to actively cool not only the void space (air) but the surrounding rock are now being explored.
Home heating and utility-scale electrical power generation are different in kind, not just scale. They merit different language.
I do agree that present usage is often vague and similar terms are used to describe wildly different applications.
"Residential" or "end-use" vs. "regional" or "grid scale" are among the differentiators I'm familiar with.
Marketing is another driver of much confusion, as selling a ground-loop heat pump sounds much more impressive when described as "geothermal heat pump". The latter is ... stretching definitions at the least, if not openly misleading.
Solar will not take over land people want for anything else. (Although, desert solar farms are a very bad idea, but thus far easy to sell to ignorant investors.) Solar coexists synergetically with existing uses, most especially reservoirs and canals, but also pasture and crop land, and industrial rooftops. Likewise, wind coexists nicely with pasture and boat traffic.
Utility storage will mostly not be in batteries, but in media much, much cheaper.
As an ignorant doofus, care to explain why? Sticking solar panels in otherwise empty land seems like a good idea.
Float them on a reservoir instead, and conversion efficiency is improved to as much as 23%, lifetime increased to... nobody knows yet. Evaporation is reduced. Biofouling underneath is reduced. Some wildlife prefers the shade, under. Turtles like to climb up on the edge. And, cleaning is easy. (Search: "floatovoltaics")
Float them on a canal, likewise; the evaporation and biofouling reductions are extra important there. California estimates they could generate 12 GW on its canals, and prevent millions of gallons of evaporation loss every year.
Stand bifacial (double-sided) panels in fencerows on cropland, running north-south, far enough apart to drive a tractor and stuff between. They pick up morning and evening sun, while protecting crops from heat stress and cutting evaporation. Some crops yield more, few less. When you have plenty of crop land, you don't need them to pick up every last bit of sun; you have plenty of room, so they can be spread out. You could grow berries or cherry tomatoes under, whatever else you grow. They don't get so hot in fields, either, and the vertical mounting keeps dust off. And they produce revenue year-round. (Search: agrivoltaics)
They also do well in pasture, where the livestock keep the weeds down.
On some crops, you want them horizontal above the plants to protect from freak hailstorms, heavy downpour, and harsh noonday sun.
We all like parking under solar panels in parking lots, where they keep the rain off on our way to the car, and keep it from getting too hot inside. And, they make roofs last longer; not just on houses, but on warehouses, factories, airport terminals, malls, what have you.
Finally, deserts are usually a long way from where people want the power.
There is absolutely no shortage of places to put solar panels where they will work better and longer, and do other good besides.
I'd wonder what the cleaning trade-offs would be for 'erected over' vs 'floating in' installations?
Marine growth on the float is OK; I think the panel itself is held up out of the water. I guess a worry could be about heavy things attaching and eventually sinking it, requiring that the carrier be replaced.
At least some canals need to remain "navigable", which needs the panels in a frame overhead. I think this is being done in India.
The last number I encountered was that there was 3GW of floating solar known installed worldwide, much of it in southeast Asia, e.g. Singapore.
There are extensive geothermal power facilities, however, and a surprising amount of the readily-accessible generating capacity is already utilised throughout the world, the primary exception being in the African Rift Valley.
What Geothermal offers that wind and solar don't is high-reliability dispatchable peaking and night-time base-load power. Those loads are low but relatively predictable. There's a challenge with geo in extracting too much thermal energy too quickly, and fractional use on an as-needed basis might result in both longer-term utilisation per site (before the rock is cooled below practical usable levels) and more reliable generation capability for a given site.
A future low-carbon / renewables energy regime will be based on a mix of sources. Geothermal is an excellent option for that mix.
So, if geothermal can get its operations cheaper, it could be good competition for wind and solar. Once plenty of storage capacity is on the grid, overproducing will not ever be a problem: the grid will absorb as much energy as any well can produce, provided the price is right.
This last is why nukes have no future: they cannot produce power at a price the market will pay.
That said, the technical challenges, and costs, of drilling through many kilometers of rock are considerable. As are those of operating geothermal generation sites based on such bores.
The far less challenging Habenro project in Australia is a case study of early estimates being proving exceedingly optimistic:
I'd become aware of that specific project about a decade ago through ... a highly-positive puff-piece published in an overly-friendly Australian energy publication. The tone and fast-and-loose benefits descriptions set off a few alarms. The project ended up as a failure, the company running it pivoted out of geothermal energy.
https://old.reddit.com/r/dredmorbius/comments/1wpa90/how_not...
http://www.theregister.co.uk/2013/05/02/geodynamics_habanero...
I suspect most of the other links in my Reddit piece are dead, though archive copies may exist.
Energy Watch article archive: https://web.archive.org/web/20130805195650/http://www.energy...
ASX link seems dead.
Advertiser on SA Geothermal: https://web.archive.org/web/20130420153842/http://www.adelai...
AGEA: https://web.archive.org/web/20140126042126/http://www.agea.o...
All of that said:
- Geothermal does have long-established, well-proven, economical capability.
- I'm convinced humanity's energy future will largely be renewables.
- The ultra-deep plasma-torch borhole stuff might work. It's something of a longshot though. That said, I'd like to see related technology (e.g., the boring bits) and trial projects attempted.
Even the Habenero project wasn't an utter waste --- it was an experiment, just one that didn't pan out. It would have been far more worthwhile for it to have received coverage which portrayed it accurately, however.
I would like to see steam turbines displaced by something that doesn't need so much maintenance (high-pressure CO2?), so that geothermal could become more competitive with other renewables. But developing tech like that is no walk in the park. GE will do it when their market for steam turbines starts to fall off, faced with renewables.
The main problem with geothermal is that it is quite a bit more expensive than solar and wind, with an "opex" renewables don't have: regular overhauls of the steam turbines. So, a bet on geothermal would be a bet that storage built after there is enough renewable generation to charge it from will not also be cheap. Not a good bet: storage is, for the most part, just E = mgh and E = Fx, requiring only mid-20th-century engineering. (That is not to say more exotic methods won't also be used. Synthetic ammonia, good for fuel and fertilizer, is also a good storage medium. And, better battery chemistries surface all the time, with megafactories for certain of them already under construction.)
Just now, most storage schemes you read about have not had the professional engineering treatment, so are over-complex and expensive. When actually built out, much cheaper, simpler, and more reliable versions of those things will be used. (But Energy Vault's will not be. I predict they will pivot to something orbital soon, to string the saps along.)
Drilling for geothermal might get a lot cheaper, using the tech described in the article, but you still have the steam turbines. That new gadget that turns heat radiation directly into electricity with no turbine might eliminate that expense and make geothermal competitive, but it also might turn out too expensive to use.
So 1 terrawatt = 47 terawatts