Towards sustainable desalination (2019)
unep.org
unep.org
They setup solar and wind farms at the time to offset the energy required and to my knowledge there's never been any environmental issues with the brine discharge.
They also recycle water here by treating wastewater and pumping it into the ground water where it blends in with water in the aquifer - some of which is later extracted. They pump into the aquifer rather than directly into the water supply because people had an "ick factor" about drinking treated wastewater regardless of how filtered it is.
I think desalination is one of those things that would become plausible at scale, and that also would be a transformative change in human's relationship with the planet.
It's not just water. Most of the big issues we have on this planet have an energy component to them either directly or indirectly. Energy is a bottleneck. Making energy very cheap enables a lot of positive changes.
Take agriculture (and by extension, world hunger) for example. Agriculture requires water, light, warmth, and fertilizers. We can make clean water with desalination. We make fertilizers via energy intensive processes to produce ammonia (usually by first creating hydrogen). Light and heat we can create in green houses with yet more energy. With enough energy, you can grow bananas in Iceland and go skiing in Dubai. Neither of those things is science fiction btw. They really grow bananas in Iceland using geothermal energy and there is an indoor skiing hall in Dubai.
There's also synthetic fuel production, transport, heavy industry, etc. All bottle-necked on energy. With synthetic fuels, there's a cross over point where that gets cheaper than drilling up oil and shipping it half way around the globe to refine it into fuel (all of these things take a lot of energy). It's not that far off.
In fact, since the end product (desalinated water) is easy to store in great amounts, desalination could be one of the processes that would run when surplus energy is available.
With current prices for renewable generation and storage, an overcapacity in production of 300-500% seems to be the optimal from a system cost perspective: In such a world, lots of surplus energy would be available at low cost for a flexible consumer such as this.
That totally happens already. When you look at a windy, sunny day in Germany in the summer, you'll find that renewables are producing so much energy that prices drop into the negative and somebody is being paid to burn it.
I think we'll see this more often with more renewables and it might be a chance to have, not yet highly optimized, processes running that need a lot of energy. Desalination is one of those, so is production of hydrogen.
Given the volume of the oceans compared to average flow of Niagara Falls, the orders of magnitude difference in volumes makes this an insignificant problem, no?
If you dump the wastewater brine offshore a mile or so there may be local concentrations that are polluting but how does this become problematic in the vast open oceans?
If you dump brine, it will stay together as a cloudy salty area for quite a while. No matter where you dump the brine, it will be affecting some ecosystem somewhere.
There are videos of divers moving through different strata of salinities in the ocean, sometimes in caves. It looks as though they’re breaching the water-air layer, but they’re actually coming through a water-water layer of different salt densities.
So dumping in the ocean will still change a local area of ocean to toxic levels of brine concentration.
I’m 100% for desalination, but it’s a tough issue to solve.
https://www.sciencedirect.com/science/article/abs/pii/S00431...
Given the greater currents in the Pacific and Indian oceans I’m sure this could be managed well by dumping out to sea, although I’m sure many plants just pump out near the local beach.
Environmental "concerns" like brine discharge are frequently raised without any reference to the quantitative scale of the impact. Desal plant brine discharge is a highly localised environmental impact.
There's an odd bias we have where highly localised environmental impacts are readily accepted when they're visually obvious (a car park eradicates all life in the area of the car park), but when it comes to the open ocean, a localised impact is not accepted.
I know that it was an expensive device but there was promise to make it affordable enough to become ubiquitous. They seem to have given up on it?
Look at energy requirements of desal vs. fresh water pollution proliferation.
10-14 kwh required to desal 1000 gallons of water.
50% of world's food supply is powered by proliferation of phosphorus and nitrogen rich fertilizer and their corresponding runoff.
Wait, are those numbers right? That doesn't look that expensive to me. That's a roof full of solar for lots of water per day?!
Edit: nope I checked and that is a correct number.
Regarding your greenhouse: Does it sit flat on the earth? I'm thinking about lowering the greenhouse at my parents house somewhat into the earth, I think 2 feet would already help with keeping it warmer...
A lot of people do something like this-
https://ceresgs.com/environmental-controls/gaht/
I did the math and used a kill a watt to monitor the usage and just doing a little space heater hooked to an Inkbird temperature controller was plenty economical for me. I have cheap electricity where I live though. About 30 cents a night when it is freezing outside. So absolutely worst case scenario would be $9 a month which I can handle for how much joy it gives me to be able to grow plants in the winter.
Sounds great with your energy prices. At that rates, I'd go for electric heating, too. :-D
If the salt were made into a boat, it could be sailed away (moved more easily than on land) and could mix with seawater over a much wider area. Even if it sinks after a short period, it would still be in a rock-like form that would mix with seawater over a longer time period. Similar to how the salt in the sea came from rocks originally?