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Comment by achow | Hacker News Reader

Seems like this idea is couple of decades in making..

A seawater greenhouse is a greenhouse structure that enables the growth of crops in arid regions, using seawater and solar energy.

The technology was introduced by British inventor Charlie Paton in the early 1990s and is being developed by his UK company Seawater Greenhouse Ltd.

The technique involves pumping seawater (or allowing it to gravitate if below sea level) to an arid location and then subjecting it to two processes: first, it is used to humidify and cool the air, and second, it is evaporated by solar heating and distilled to produce fresh water. Finally, the remaining humidified air is expelled from the greenhouse and used to improve growing conditions for outdoor plants. https://en.wikipedia.org/wiki/Seawater_greenhouse

Making Namibia’s desert green using seawater https://www.newera.com.na/2016/07/08/making-namibias-desert-...

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> On a sunny day, up to 39 megawatts of energy can be produced – enough to power the desalination plant...

They don't appear to be using evaporation and distillation, but instead generate electricity and run the desalination plant with that... I'm guessing, by pressured osmosis, as used elsewhere in Australia.

My question is: why don't they do it as you assumed? Whatever a solar still might lose in efficiency, it must surely make up in the reliability and simplicity of no moving parts.

During the pilot project Sundrop decided to simplify the design. The equipment for the distillation of the hot humid air proved to be complicated to produce with the resources available at the time and they decided to go with a more conventional method.

Personally I think the original design could be made to work, but it needed more R&D than Sundrop was prepared to spend at the time.

Indeed, trying too many new processes all at once would be setting yourself up for failure. Now this works, the other parts can be addressed and further efficiencies made.

There's a great video on youtube about the Advanced Passenger Train in Britain in the 80s where they tried a few too many new things with predictable results.

I can't help but imagine this technique being handy when settling on or terraforming certain planets.

Certain planets with an abundance of salt water?

Or flooding them with such, first? Not that I know which currently-known planets we could do that on.

Thermonuclear bomb the Mars ice caps. I think I read that in a scifi book.

Mars is really cold. At the equator the thin atmosphere can heat up reasonably at noon, but it still hits minus 100f at night even at the equator.

There are subterranean brine rivers on mars so large that they can be seen from orbit.

https://www.nasa.gov/press-release/nasa-confirms-evidence-th...

Not quite. Here is a link that's probably easer to understand.

https://science.nasa.gov/science-news/science-at-nasa/2000/a...

We are not looking at underground water in those pictures we are looking at evidence of likely very short term water causing a tiny amount of erosion in just the right situation. However, it's long been known there is actually quite a lot of ice on Mars.

Slam a shitload of comets into it, like in Seveneves.

If you include moons, plenty of water on Europa, though don't know if it's salt water. Generally I'm against terraforming though, especially because we've not shown we can be good custodians of our home planet.

  Generally I'm against terraforming though, especially because we've not shown we can be good custodians of our home planet.

Which to me doesn't logically follow. Send a few politicians to some $%^# hole of a terraformed moon and see how long it takes before they decide taking care of the earth is important. Second, we are basically terraforming earth, the problem is that we don't really have a clue what the outcome will be. Its the equivalent of giving a 5YO a soldering iron and a laptop and letting them play.

Just because we can and do terraform doesn't mean we should. I'm a big believer in appreciating nature for what it is rather than seeking to dominate it. The Sahara Desert is a great example... Imagine we could cheaply and effectively green the Sahara desert, why would we not want to do that? Perhaps because it adds to the diversity and richness of our world. If you only consider this practically then it makes no sense, as very little grows in the desert, so it's less useful than more fertile land, but when viewed as a cultural asset it absolutely makes sense to keep it relatively untouched by human influence.

This is a stark example, but it applies across the board. As I hinted at before, dominating something is less interesting than working with it.

> I'm a big believer in appreciating nature for what it is rather than seeking to dominate it.

Is a termite mound any less "nature" than some random patch of earth and rock? What about bird nests, beehives and beaver dams?

We are nature. The Universe is one continuous stream of change.

> "We are nature. The Universe is one continuous stream of change."

Sure, but we're not the only expression of nature that exists. By optimising a planet for the desires of one type of organism you do not necessarily optimise it for all living organisms. If we want to be good custodians of a planet we share with other organisms we should seek to balance our needs/desires with those of other organisms we live alongside. Due to our position on the planet at the top of the food chain due to our abilities gained through tools/technology we have a greater ability to influence the quality of life of fellow Earth inhabitants. Whilst nature can be seen as indifferent, humans are not indifferent about the world they inhabit. If it makes it more straightforward to understand, see it as selfishness... I want to live in a world with a rich diversity of life that can thrive alongside humanity because it makes life more interesting for me.

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