How a Solar Revolution in Farming Is Depleting Groundwater

https://e360.yale.edu/features/solar-water-pumps-groundwater-crops

by rustoo • 2 years ago

124 120 2 years ago

e360.yale.edu

throwaway5959• 2 years ago

How is this a solar problem? The article clearly states there’s diesel pumps as well that do the same thing.

warble• 2 years ago

Cheaper to run constantly.

actionfromafar• 2 years ago

It's cheaper to extract the water than it used to be.

ethbr1• 2 years ago

Diesel has a consumable that must be purchased when the pump is run.

With solar, there's presumably less difference between "run the pump 24/7" and "only run the pump when cost efficient."

It's essentially the same argument in favor of solar power generation. Fossil fuel generation = plant-capital-cost + fuel-per-generated-unit. Solar generation = plant-capital-cost + negligible-wear-per-generated-unit.

pstrateman• 2 years ago

The water being pumped is basically a battery.

So it's much more effective than solar is on the normal grid.

h0l0cube• 2 years ago

Even still, solar has just enabled agriculture on places and on margins that it wasn't viable before. Agriculture itself is also an enabler of the problem, but not the actual problem of the moment. The real problem is how do we, on limited resources, feed a global population that is increasing in size and wealth (and attendant waste)?

tfigueroa• 2 years ago

Exactly. The problem is the excessive water extraction, not the technology making it cheaper.

richrichie• 2 years ago

Technologies have side effects - some good, some bad. This effect of solar i admit i had not thought about.

tomrod2• 2 years ago

It's not a direct effect of solar. It's cheaper energy with undisciplined resource abuse.

yieldcrv• 2 years ago

its an awareness problem in both belief of doing something more environmentally friendly and cost

toss1• 2 years ago

It is not a solar problem.

It is a Tragedy Of The Commons problem.

Solar just happens to be an enabling technology. Other technologies that brought cheap power to those areas would have done the same thing, e.g., wind or very cheap diesel (biodiesel?) would have the exact same effect if they happened to arrive first. Putting Solar in the headline and as the culprit is a truly cheap shot.

The real problem is that now that power is cheap, it is to everyone's individual advantage TODAY to pump more, but everyone's disadvantage tomorrow when the groundwater reserves run dry. Classic Commons problem, and it's screaming to the inevitable result. The only solution is some way to monitor and regulate the draw from the groundwater.

cutemonster4• 2 years ago

I wonder what other Tragedy of the Commons enablers lie waiting, undiscovered. (AI maybe in some ways can be one?)

The only solution

But is it really a problem, from everyone's perspective?

Because, if water is scarce, then, those with money become even more important and wealthy -- they're the only ones who could afford really deep pumps? And now they can sell the water, for more and more money. What's not to like about that?

fnordpiglet• 2 years ago

From the article:

None of this should be seen as a condemnation of solar power, says Balasubramanya. “The fundamental problem is not the solar technology itself.” Whatever the technology, “if the cost of pumping is zero, then people will pump unless some restriction is put on them.”

—

The article also discusses that the panels are much cheaper to run than diesel and are subsidized by agencies and governments while the diesel pumps are not. So, yes, it’s not specifically about solar but about the economics of solar.

Jedd6• 2 years ago

In addition to the ways described in sibling responses to this question - diesel pumps suck, solar (submersible) pumps push.

In practice you can't suck more than about 8 metres (in theory it's a bit more), and while there are ways you can force a ground-based pump to get water up from a deeper depth than that .. the economics work against you.

A submersible pump - DC-driven by solar typically - can sit at the bottom of your bore, and push 100 metres or more upwards. No sucking required, so they're relatively simple and efficient.

(My little 75mm x 500mm submersible solar pump, for example, is pushing about 5k litres per day through 600 metres of 50mm pipe, with a vertical (head) of ~40 metres from bore water level.)

schneems• 2 years ago

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?

owyn2• 2 years ago

I am too but the answer is zero, and nobody knows but probably a long time. The whole Central Valley is like 30 feet lower now. A bit of rain isn't going to fix that.

scheme271• 2 years ago

Probably just a fraction. A lot probably evaporates and anything that the plant absorbs and incorporates just goes away when crops are harvested and shipped elsewhere.

e40• 2 years ago

From what I’ve read, it takes a very, very long time to replenish the water table. Eons.

contravariant2• 2 years ago

I'd see what the Dutch water suppliers have to say about it, pumping up ground water and managing the water table is kind of their thing.

cutemonster4• 2 years ago

Apparently pumping up, yes, managing, less. See this comment here:

https://news.ycombinator.com/item?id=39732506

... ground water shortages. Reason: farmers like irrigating their land (much of it below sea level) with ground water because it is cheap ...

ramraj07• 2 years ago

Each aquifer is differen: some recharge quite fast with two rain seasons. Others take thousands of years.

westurner3• 2 years ago

What are some solutions for water table depletion and how comparably sustainable are they?

How much water is extracted from air by PV panels that output H2O, and what are the impacts?

Do drilling and fracking consume lots of water and create holes through aquifers? Do holes in aquifers cause aquifers to drain out to lower chambers of the earth?

Historically, people have moved to where the water is.

Is there a subsurface ocean on Earth or Mars?

Is there enough of a thermal gradient between very deep wells and surface water to generate energy?

How many humans operating humanoid robots operating construction equipment does to take to build irrigation canals?

Perhaps helpful new solar distillation tech for #Goal6 #CleanWater:

- "Desalination system could produce freshwater that is cheaper than tap water" (2023) : "Extreme salt-resisting multistage solar distilation with thermohaline convection" (2023) https://news.ycombinator.com/item?id=39507692

Perhaps there are already sustainable salt-tolerant plants without GM; algae, kelp, sargassum

There is plenty of salt water on Earth. Does life on earth depend upon and/or derive from ocean thermohaline cycles?

fredrikholm• 2 years ago

What are some solutions for water table depletion and how comparably sustainable are they?

Water harvesting has been successfully applied to thousands of villages in India and parts of northern Africa.

The Paani Foundation is especially amazing, as they annually lift hundreds of villages from dry wells and tanker dependence to tens of feet of water in wells and ponds in as little as one rain season using nothing but planning and cheap labour (the villagers).

westurner3• 2 years ago

I see videos of successful bund dig operations; digging half-craters to catch water apparently keeps the water from flashing off.

Tilling turns topsoil to dirt due to solar radiation.

No-till farming methods like residue mulching prevent soil depletion and retain water in topsoil; in order to create healthy soil as an output.

Hugelkultur is basically residue mulching and rainwater catchment.

Removing all of the trees reduces the level of water in the air and soil.

What sorts of agricultural machines can service bunds, raised beds, and hugelkultur mounds instead of rows?

heavyset_go• 2 years ago

You can think of the water as ancient. It's been there for a while and it took a long time to get there.

dreamcompiler• 2 years ago

The water in most of the big US aquifers is at least 10,000 years old. There are some exceptions like the Edwards Aquifer in Texas but for most, rainwater is irrelevant. The water was put there by glaciers during the last ice age and once it's gone, it's gone forever.

This is why most groundwater pumping is properly called water mining.

lifeisstillgood• 2 years ago

I simply assumed it was refilled by rain … darn half remembered geography lessons!

Amazing - if it was a mineral or metal then there would be a mining company charging market rates for the mining … what is happening in this case?

WithinReason2• 2 years ago

FTA: "Irrigation is responsible for around 70 percent of the global underground water withdrawals, which are estimated at more than 200 cubic miles per year. This exceeds recharge from rainfall by nearly 70 cubic miles per year."

So 65% makes it back.

_heimdall5• 2 years ago

These numbers could be wildly innacurate. We have no good way of measuring this at scale and end up using modeling to answer these questions. Models are only as food as the inputs though, and we don't know what we don't know.

_heimdall5• 2 years ago

In the real world these systems are way too complex to have specific answers like this. We simply don't know, and have no way of knowing for sure.

The best, and my opinion only reasonable, answer to that kind of scenario is to just not intervene. We shouldn't be sucking water out of aquifers at such a scale that the water level drops when we have no idea of the long term impacts.

Jedd6• 2 years ago

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.

Certainly it would require less water volume, 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).

peterleiser3• 2 years ago

If you don't irrigate during the day in hot climates some crops will die, and the yields will be terrible for most.

Jedd6• 2 years ago

If you don't irrigate during the day in hot climates most crops will die

That is clearly not true.

Most crops are fine with watering after sunset / before sunrise.

fbdab103• 2 years ago

Doesn't that mean we should stop growing crops in such regions?

nyokodo3• 2 years ago

pumping during the day into a storage tank, and irrigating at night

Or, irrigate during the day but use sub-surface drip irrigation. [1]

1. https://www.ksre.k-state.edu/irrigate/oow/p05/Evett.pdf

Jedd6• 2 years ago

Yes, sub-surface, or drip close to root zone, is perfect -- however that's really expensive, in terms of capex as well as maintenance, harvesting, etc.

Drip systems tend to require a) a lot of pressure, and b) a very consistent pressure, to get reliable output. These are also expensive to buy & run.

Drip or leaky-hose type underground systems are difficult to maintain (I've tried!) just because you can't see them. The way you find out something's wrong is usually because a plant or an area is looking very very happy, and other plants / areas are dying off.

Under-mulch is good, but doesn't lend itself to broadscale cropping as described in TFA.

a_gnostic2• 2 years ago

Also, evaporation losses at leaf stomata can be adjusted with carbon dioxide.

_heimdall5• 2 years ago

If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.

Jedd6• 2 years ago

If one tries this approach I'd recommend pumping into a holding pond, ideally up hill from the land to be irrigated. Tanks would be absolutely massive for a crop on any meaningful scale, especially if its big enough to be putting a dent in the aquifer.

Sure, but almost all the countries TFA mentions are generally farmed by small landholders, so irrigation via stored water is not infeasible. The mammoth style broadacre tiny-return-per-hectare, heavily mechanised, fertiliser- and insecticide- reliant style agriculture popular in the USA isn't so common in these places.

The 'dent in the aquifer' you mention (and TFA dwells upon) is because there's thousands of people doing the same thing at the same time to the same aquifer for years on end.

Regrettably TFA doesn't talk volumes, other than three mentions of 'cubic miles'.

Apart from an exasperated 'why do they use anything but metric?' sigh, it's also obviously a heavily aggregated figure across large geo regions.

These small holdings with their panels + pump per field, pulling from an increasingly deep water table, are presumably extracting probably in the range of 10-20 kilolitres of water per day - the size of an average plastic water tank that has a one-off cost about the same as a submersible DC pump + panels. (Lined steel, concrete, etc, become more attractively priced at larger volumes.)

So, yes, absolutely, if your geography allows, then put in a megalitre+ sized hole in the ground up-hill, cover it to reduce evaporation & algae, fence it to prevent animal damage, etc. Happy days.

photochemsyn• 2 years ago

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.

See the Ogallala Aquifer under the Midwest:

https://www.kcur.org/2023-04-04/with-the-ogallala-aquifer-dr...

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.

leros• 2 years ago

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

Gibbon1• 2 years ago

In the Santa Clara Valley farmers pumped enough water out of the ground in the early 20th century the ground dropped a dozen feet in some areas. Bad thing too is that once an aquifer settles like that it's carrying capacity is permanently reduced.

Also in southern California there is a fair amount of previously productive farm land that is salted up and useless. That'll happen to the north Texas farmers you've mentioned. If they're having to switch crops they have another ten to twenty years and it's all over.

Edit: Even better Jakarta is sinking so bad because of ground water pumping that the government plans to abandon it.

neurostimulant• 2 years ago

It's odd that foreign media reporting the Indonesian government plan to move the seat of government from Jakarta to Borneo as primarily motivated by the sinking of Jakarta (it affects the northern part of Jakarta, while the goverment is mostly operating in Central Jakarta), while the other more important (to the government) reasons are usually under-reported, such as to reduce the java-centric development, improving the government's efficiency by moving various government agency closer together instead of scattering everywhere over the huge megacity with traffic jams everywhere, and improving the government image because foreign diplomats will arrive in a pristine, green city instead of concrete jungle with bad air and traffic jams everywhere.

hinkley6• 2 years ago

I did the math once and the amount of water we’ve pumped out of the aquifers worldwide and not replaced is worth more than a mm of sea level rise.

TrainedMonkey• 2 years ago

Please show the math and sources, I would love to see the sauce.

Cerium• 2 years ago

Related: Humans pump so much groundwater that Earth’s axis has shifted, study finds

https://www.cnn.com/2023/06/26/world/pumping-groundwater-ear...

hinkley6• 2 years ago

Correction: 10 cm

https://news.ycombinator.com/item?id=39736050

cameldrv• 2 years ago

I remember reading about how in the Soviet Union, there were places they were irrigating with brackish water and how they were now infertile. The obvious conclusion was that the Soviet economic system was busted to permanently destroy land for some temporary gain.

throwup238• 2 years ago

The American equivalent is the dust bowl. The ancient equivalent is the desertification of Mesopotamia. Etc. etc.

Humans are bad at long term thinking.

Sam6late• 2 years ago

Is it close to these huge sinkholes in Turkey? https://www.dailysabah.com/gallery/turkish-farmers-worry-abo... Because these in Texas seem tiny in comparison https://www.texastribune.org/2023/08/16/texas-drought-heat-a...

itsanaccount3• 2 years ago

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.

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.

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.

Voultapher2• 2 years ago

Picture a roller coaster where the carts have little steering wheels .. that do nothing. We like to imagine we are in control, but zoomed out we behave quite predictably, chasing that unsustainable growth.

I feel you, and I'm not sure how to explain this to children. How honest should we be? I believe there is no version of this that ends well, we are left with outcomes to our decisions on the spectrum of awful to really awful. There is no arguing with physics.

lettergram2• 2 years ago

I actually argue the opposite zooming out. Zooming out our trajectory is up and to the right, like a hockey stick. Almost on every level. We’ve done that with all these disasters that have always happened. Almost like we can innovate or something

VelesDude2• 2 years ago

Stephen Harrod Bruhner once said that society is like of like a plant. It produces its off spring to spread out when it is at its peak health. It makes the biggest fruit just before it dies.

That we started sending intergalactic space probes in the 1970s when, in the west, the energy use per capita was to start to peaking is a funny conincience. Some of those are probably accidentally carrying microbes that will be suspended in state for potentially hundreds of millions of years.

It isnt something to take too seriously but it is a fun concept to contemplate.

Maybe we have the exact same intelligence for logevity as a tomato.

a_gnostic2• 2 years ago

Hoogle cultures,and capturing runoff reduces your agricultural water needs.

https://permacultureapprentice.com/permaculture-water-manage...

nitwit005• 2 years ago

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.

jillesvangurp• 2 years ago

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.

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.

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.

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.

vitiral• 2 years ago

Cleaning solar panels? Did you read the article? It's about solar pumps enabling aquifer exhaustion when used for agriculture

miohtama• 2 years ago

This is exactly what happens in Spain:

https://www.euronews.com/green/2024/02/01/spain-expected-to-...

Agriculture is responsible for 80% of water use. Because water is not market priced for farmers, farmers use very inefficient surface irrigation, causing 50% of water to vaporise.

Then nobody does anything and wishes the government pays them to switch to more efficient irrigation systems.

Edit: Looks like government is doing exactly this - paying farmers to reduce water usage, instead of having a fair price for the water https://www.catalannews.com/drought/item/government-and-farm... Hopefully this leads too a real change is not just a socialist solution kicking can down the road.

mbgerring• 2 years ago

Why not just tax water-hungry crops?

j-pb• 2 years ago

The bigger issue is that 1/3 of crops are used as animal feed. No matter how water efficient they are, you still need 10x as much of them for the same amount of calories.

It'd be much easier and have a bigger impact to just go plant-based.

cutemonster4• 2 years ago

I've read about that, related to farmers shopping down the rain forest in Brazil (to grow beans for hamburger cows). But I don't think it applies to poor development country farmers?

It's not as if the farmers in India are feeding cows and everyone feasts on hamburgers. And in Yemen, they're growing that qat drug (not meat)

lotsoweiners2• 2 years ago

It'd be much easier and have a bigger impact to just go plant-based.

Ok but this is a non starter since myself and a huge chunk of the western population will say no thank you.

nonoesp• 2 years ago

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.

vasco• 2 years ago

When given the chance of reducing your footprint or improving your life, is it that surprising this is the outcome? Specially in developing countries.

_heimdall5• 2 years ago

Farmers often don't have a choice on this. A vast majority of operations depend on debt and government subsidies just to get by, both come with strings attached related to both farming methods used and required yields.

I'd propose that the more sustainable solution here is to help get out of a farmers way (both financially and regulatorily) rather than trying to encourage get another round of changes. I'm assuming the encouragement would have to come similar to the current ones, as either legal requirements or strings attached to the money.

Farming is a nearly impossible business to be in today with depending entirely on debt and subsidies, at least in the US. Prices are insanely low relative to the cost and risk of raising animals and farming crops. Until that problem is fixed, farmers have little choice other than to look for expense optimizations anywhere they can (regardless of long term damage) and follow whatever rules are tied to the money they take.

qwerty456127• 2 years ago

What's the state of technology in producing fresh water from sea water? Isn't there any serious progress making it more efficient and cheap?

pfdietz• 2 years ago

It's become progressively cheaper through incremental engineering improvements. The cheapest way is generally reverse osmosis, especially on water that is just brackish.

But it's also generally cheaper (per unit of saved water) to just use water more efficiently. Agricultural water use can be enormously economically inefficient in the US.

blendo2• 2 years ago

I don’t think solar powered irrigation is practical.

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.

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.)

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.

These are my wild guesstimates informed by some orchard experience, but please correct me if my numbers seem badly amiss.

ps: With PG&E power, we currently pay about $400/acre, per year.

20after4• 2 years ago

There are no batteries involved with the type of solar pumps the article is talking about. They are likely 3 phase pumps powered by variable frequency inverters. The inverters are similar to the VFD¹ motor drives commonly used with industrial machines.

I'm not sure where you came up with a $20,000 cost estimate but it's likely a lot less than that. Particularly if you buy the cheapest stuff direct from China, avoiding avoid the dealers/installers who are probably marking up the equipment by more than 100%. Solar panels and the associated electronics have drastically dropped in price for the past several years. It should be possible to get 200 watt panels for $50-100 (or maybe even less if you buy a lot of them) That's something like $250-$500 per kW of panels. Make it $1000/kW to cover mounting hardware and wiring. The pumps / inverters are maybe a few thousand for a fairly large system.

I'd say the total should come closer to $5,000-$7,000 per acre based on the power requirements you specified.

[1]. https://en.wikipedia.org/wiki/Variable-frequency_drive

Heliosmaster• 2 years ago

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: https://www.youtube.com/watch?v=79VUAFq2rbg

How a Solar Revolution in Farming Is Depleting Groundwater

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