Eli5: why haven’t we started considering or implementing large scale desalinization in response to our water shortages?
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Desalination requires an absurd amount of electricity and is really expensive. It’s not at a point where it’s really worth it on a large scale.
Desalinization is really expensive and difficult to do in large quantities. Pretty much, its low on the list of options compared to just about everything else. Outside of very specific areas (such as some in the middle east with no other options) its still a better option to do any other method over desalinzation.
Also, geography. Transporting water is really inefficient, so unless you’re staying a small area or along the coast, getting the water inland is a big problem. We’re generally no where close to having it be effective to do this
We have, it’s just very difficult to implement. The city of San Diego spent $1 billion on making a desalination plant, but even that can only handle a small percentage of that city’s water needs. Desalination is expensive because it requires a LOT of energy.
There are quite a number of desalination plants around the world. It is one of the solutions to water shortages that is being implemented. And while it is quite stable as it provides a constant source of clean drinking water it is the most expensive. Not only to build and maintain but it also requires a lot of electrical power.
Desalinization is expensive and requires enormous amounts of energy. It also only works on the coast, and many drought-ridden areas are well inland.
Money plain and simple. Desalination of seaworthy is prohibitively expensive. After desalination, the water would have to sell for about 10 to 15 dollars per 1000 gallons. Nobody I’d gonna pay that to irrigate a crop or water their lawn or flush their toilet.
Large scale desalinization is in use today although the definition of “large scale” is pretty important. While people discuss water shortages as a global issue, the crisis areas are local. Large scale desalinization in one location cannot solve the problem of water shortages hundreds of miles away.
Desalinization requires several things
1) Local source of salt water. This pretty much rules out this solution for any inland area. Water is HEAVY. Transporting it takes lots of energy and infrastructure.
2) Large amounts of available energy. Here you have to consider costs and alternative usage. In a poor and energy starved location, energy would either be too expensive or have many alternative uses of greater benefit.
3) A relatively concentrated population that would benefit from it (locally!). This makes desalinization useful in places like Singapore, Israel or Saudi Arabia in cities. It won’t be useful for sparse populations spread out across large areas.
To the matter of scale, desalinization cannot (at this time) be a solution for anything other than human use. Humans might use up to several tens to several hundred gallons a day per person. Wide scale agriculture, on the other hand, uses water by the acre-feet – ie hundreds to thousands of times more water than cities, by and large. And the productivity (economic output) of cities is FAR higher than agriculture or livestock farming.
So I’m going to talk about this from the perspective of the western United States. Obviously things will be different depending on where you live.
There isn’t really a “shortage” of water in the United states. I mean there *technically is*, we don’t have as much water as we want to use, but that “shortage” has far more to do with what we use the water for than lack of rain or snow.
Industrial, home use and commercial water use make up only 14% of all water use in the United States. There’s plenty of water in the state that even if those users quadrupled their demand (they never would), we would have no problem meeting that need. The category that is actually using all of our water (86%) is agriculture. Now agriculture is really important and I’m not saying we should stop growing food but many of these farmers are receiving huge allotments of water at ridiculously cheap prices (tens or hundreds of gallons per penny, orders of magnitude cheaper than water to salination could ever provide). For varying reasons too, they are not being incentivized to be very efficient with their water use either. In fact, because many of their water allowments are written weirdly into state laws, they actually need to use an excess amount of water or they lose it. Even the ones who aren’t incentivized in that way are getting water so cheap that they’re frequently just using it to dump in the desert to grow incredibly water inefficient crops like alfalfa for cattle feed.
Tldr: the Western United States has plenty of water to meet its needs. If we could figure out how to stop vastly overusing it.
*”While there are many variables related to the cost of desalinated water…..a good rule of thumb is $1.10-2.40 per 1,000 gallons for brackish water and* ***$2.46-$4.30 per 1,000 gallons for seawater desalination****.”*
Now that you have the salt out of the water, what do you do with it? If you throw it back in the ocean, pretty soon the ocean will be too salty to sustain life. No more fish? No more tuna salad sandwiches! Next, what about the chemicals used in the process? They gotta go somewhere!
What about the energy required to remove the salt? It’s my understanding that the process uses a lot of energy. That’s expensive and bad for the environment.
So, what do we do? Make drinking water or kill the planet?
Water in general is a cheap widely available product, desalination is expensive environmentally damaging and energy intensive.
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