Speaking purely from a technical perspective, if renewable energy were to scaled up somehow it probably makes sense to do it. I don’t know of any downside other than the immense energy inefficiency of the process

When you take salt water and pull out all the water, you're left with enormous amounts of salt-brine. Then you're left with the question of what to do with the new pile of waste you've created.

Guess how the Middle East handles this problem.

Producing one liter of fresh water produces about 1.5 liters of brine, though there are big differences in the “recovery ratio” (freshwater to brine) between plants, based on the salinity of the source feed water and desalination technology used, Jones explains.

Every day, the nearly 16,000 desalination plants in 177 countries produce 95 million cubic meters of water and discharge 142 million cubic meters of brine.

Over a year, that’s enough to cover Florida under a foot of brine, the authors say.

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One problem with brine dumping is that it depletes the oxygen dissolved in the receiving waters around the plant, explains Jones. “High salinity and reduced dissolved oxygen levels can have profound impacts on benthic organisms, which can translate into ecological effects observable throughout the food chain,” he says.

The toxic chemicals used in water pre-treatment or as anti-scalants and anti-foulants in the process don’t bring benthic life joy either.

“Development of energy-efficient, cost-effective and environmentally benign concentrate management systems is critical if desalination is to become a major part of a sustainable water future,” pointed out Pei Xu and colleagues in Environmental Engineering Science in 2013.