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In the thread on what a future with fusion would like, where energy costs approached zero, one of the questions posed was, "What would the future look like if energy costs trended towards nothing?"

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.

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Energy is getting cheaper very rapidly. I think there's room for an order of magnitude drop in prices per kwh on a relatively short timeline of maybe 1 or 2 decades. Basically to well below 1 cent per kwh. Maybe two eventually: ~0.01-0.1 cent per kwh. That won't happen overnight of course but there are multiple paths to potentially very substantial cost reductions still. At those price levels, energy is close to free and we'll indeed be able to address a lot of things with it.

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.

Agriculture also requires soil, and fertilizers like phosphorus that cannot simply be summoned from the atmosphere with energy.

But it can probably be summoned from many polluted waters.

Good point.

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.

> 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.

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