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How a Solar Revolution in Farming Is Depleting Groundwater

e360.yale.edu

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Re: How a Solar Revolution in Farming Is Depleting Groundwater

#131

Post by hinkley »

ajb wrote: post #86
bongodongobob wrote: post #60

Earlier quoted context omitted.

Me too because that sounds impossible to calculate.

What difficulty do you see? It's not going to be enough to appreciably change the ocean area, so isn't it just volume divided by the area of the ocean?

I think it would be 1) how accurate are aquifer and coastline topography measures (1 mm wouldn’t be far off but what about a meter? That’s a lot of inundation). And 2) how much has subsidence permanently decreased the carrying capacity of aquifers?

It could be a thing where only 50% of what is extracted can be returned. Either theoretically or safely (eg, earthquakes).

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#132

Post by 20after4 »

blendo wrote: post #128

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…

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

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#133

Post by hinkley »

Cerium wrote: post #107
hinkley wrote: post #52

Earlier quoted context omitted.

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.

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...

I used to joke that once the ice caps melt and fiddle with the earth’s angular momentum, I’ll have enough hours in the day to get everything done. Better WLB these days. And also ice caps melting is less funny than when I said it.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#134

Post by lotsoweiners »

CatWChainsaw wrote: post #124
BurningFrog wrote: post #112

Earlier quoted context omitted.

We've been farming for 10,000 years, and the vast majority of farm land is still fertile.

And thanks to fossil fuel fertilizers and land degradation a lot of topsoil is less than 60 harvests from being degraded completely.

Why can’t it be amended? My region has pretty shitty clay soil but I’m able to mix in compost, mulch, and other amendments and grow all sorts of tropical fruits and other plants that shouldn’t grow here. Am I missing some reason why the farmers have to rely on topsoil?

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#135

Post by lotsoweiners »

j-pb wrote: post #77
mbgerring wrote: post #75

Why not just tax water-hungry crops?

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.

> 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.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#136

Post by bongodongobob »

ajb wrote: post #86
bongodongobob wrote: post #60

Earlier quoted context omitted.

Me too because that sounds impossible to calculate.

What difficulty do you see? It's not going to be enough to appreciably change the ocean area, so isn't it just volume divided by the area of the ocean?

Permeability, amount of precipitation, land usage, evaporation, avg temperature, temperature variation, soil composition, erosion, wells, flood plain, wetland, etc.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#137

Post by tuatoru »

kwere wrote: post #123
tuatoru wrote: post #71

Earlier quoted context omitted.

Getting to space is not going to happen. We don't have the ability to live sustainably on Antarctica, which is several orders of magnitude easier logistically and technologically.

there is no economy in Antartica besides resource extraction, which is banned. Instead a space economy (logistics, tourism, manufacturing, research) its on the rise. No selfsufficient space colonies in the next 50 years for sure

We still don't have the ability.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#139

Post by ajb »

hinkley wrote: post #131
ajb wrote: post #86

Earlier quoted context omitted.

What difficulty do you see? It's not going to be enough to appreciably change the ocean area, so isn't it just volume divided by the area of the ocean?

I think it would be 1) how accurate are aquifer and coastline topography measures (1 mm wouldn’t be far off but what about a meter? That’s a lot of inundation). And 2) how much has subsidence permanently decreased the carrying capacity of aquifers? It could be a thing where only 50% of what is extracted can be returned. Either theoretically or safely (eg, earthquakes).

Makes sense, thanks.

Re: How a Solar Revolution in Farming Is Depleting Groundwater

#140

Post by westurner »

westurner wrote: post #120
westurner wrote: post #28

Earlier quoted context omitted.

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 subsurf…

I see videos of successful bund dig operations; digging half-craters to catch water apparently keeps the water from flashing off. Tilling turns top soil 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 tree…

> Tilling turns topsoil to dirt due to solar radiation

and oxidation.

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