I know some farmers in North Texas where they are pulling water out of a depleted aquifer. The water is starting to get salty so they're adjusting to salt tolerant variants of their crops. The ground is also starting to drop due to the aquifer draining. It's crazy to see
Ancient subterranean water aquifers are not a sustainable resource in the long run unless a recharge program is implemented that puts as much water into the system on a yearly basis as is withdrawn.<p>See the Ogallala Aquifer under the Midwest:<p><a href="https://www.kcur.org/2023-04-04/with-the-ogallala-aquifer-drying-up-kansas-ponders-limits-to-irrigation" rel="nofollow">https://www.kcur.org/2023-04-04/with-the-ogallala-aquifer-dr...</a><p>The power source for the pumps is sort of irrelevant to the question, it could be fossil fuels, nuclear, solar or wind and the end result of uncontrolled extraction is always going to be exhaustion of the resource.
The problem here is people relying on unsustainable sources of water and then using that water very inefficiently. Relative to farming, cleaning solar panels is a drop in the ocean. In terms of surface area, it doesn't really compare. And of course it doesn't help that people just let the excess water drain away. They pump it up, use it and, then it drains away to rivers and eventually the ocean. Instead, they could be recycling that water and using it for irrigation. But because the water is cheap, nobody cares about it. So it's drained and lost.<p>In the Netherlands which, depending on how you look at it, is technically mostly a swamp with really awesome drainage and pumps, we have ground water shortages. Reason: farmers like irrigating their land (much of it below sea level) with ground water because it is cheap. But they also like to keep their fields well drained so their plants don't rot in the field. So they are actively draining water from their lands while using ground water to keep them at just the right level of wetness. They use massive amounts of water and the drained water is rich in phosphates and other nutrients which is causing all sorts of issues down stream.<p>Not sustainable. The climate in the Netherlands while changing is still quite wet. And besides, two of the largest rivers in Europe flow through the country. Mostly we have issues with water levels of those being way too high, not too low. In other words, there's plenty of water. Except in the ground. Getting rid of excess water is actually a major engineering challenge.<p>Water companies are also tapping into the same unsustainable sources because its cheap and doesn't need a lot of filtering because it's also clean. So there are water shortages and calls for people to use less water, irrigate their lawns and gardens less, and take shorter showers all while we are dealing with getting millions of tonnes of excess water to the North Sea.
The margins are doubtless so narrow that it's not feasible, but pumping during the day into a storage tank, and irrigating at night (while evaporation is relatively low) would be a way to slightly improve soil (though not aquifer) recharge.<p>Certainly it would require less water <i>volume</i>, but again, the infrastructure costs for panels + submersible + storage are probably untenable in precisely the places this is needed most (and where the impacts of depleting the water table will hit the most).
I’m very naive in this space. What percent of water extracted makes its way back into the water table and how long does it take? I assume you lose some to the plant that is harvested and some to evaporation. But how much makes it back?
Pumping water is useful only when coupled with increases in water retention and runoff prevention. Like what is happening in some (arid) places like Northwest India: <a href="https://www.youtube.com/watch?v=79VUAFq2rbg" rel="nofollow">https://www.youtube.com/watch?v=79VUAFq2rbg</a>
I don’t think solar powered irrigation is practical.<p>To water 10 acres of orchard in northern California, where our water levels are “good” (wells are 100-150 ft deep), we need about a 25 hp (20 kW) well pump. That’s ~2 kW per acre.<p>A typical irrigation cycle is on the order of 10-20 hours. So budget about 20-40 kWh/acre for a cycle, and repeat every 10 days or so (crops need to dry out between waterings else disease spreads.)<p>In theory, a kW of solar panels charging a 20 kWh battery for 10 days should work to water 1 acre for an entire summer season, at a capital cost of a wildly uneconomic cost of perhaps $20,000 per acre.<p>These are my wild guesstimates informed by some orchard experience, but please correct me if my numbers seem badly amiss.<p>ps: With PG&E power, we currently pay about $400/acre, per year.
> In theory, switching from diesel or electricity to PV pumping should eliminate greenhouse gas emissions. But in practice, farmers often use their solar pumps to supplement existing pumps, rather than replacing them. And, however it is pumped, the extra water available will also encourage farmers to adopt more intensive farming methods, using more fertilizer and machinery to grow thirstier cash crops, increasing the carbon footprint of the farm.
I've wondered if all the solar panels being put in will mean some areas will never get electrical infrastructure. The local governments will see a region where the only industry generates its own power.
Viewing humanity like a single organism, this is the strategy where like a slime mold we expand to consume all resources, then most of the organism dies off while some number of spores go on to continue to the process elsewhere.<p>If we'd like that not to happen, because we like our civilizations and like not to see them crumble, we must develop some kind of governance mechanism to prevent slime mold behavior.<p>Seeing so many conversations about resource exhaustion/climate change/ecosystem collapse boil down to "nunht uh" is.. I can't even say tiring anymore. I'm beyond tired. At this point we're gonna find out exactly what behavior is encoded in human nature one way or another.