Sponge creates steam using ambient sunlight | Hacker News Reader

Sponge creates steam using ambient sunlight

news.mit.edu

69 pointsjimsojim19 comments

> A solution to this problem came from an unlikely source: Chen’s 16-year-old daughter, who at the time was working on a science fair project in which she constructed a makeshift greenhouse from simple materials, including bubble wrap. “She was able to heat it to 160 degrees Fahrenheit, in winter!” Chen says. “It was very effective.”

Love it when discoveries are made by accident.

That doesn't sound like an accident: it sounds like she considered the problem, and thought of a solution, on purpose.

The researcher having a live demonstration of its effectiveness was serendipitous.

I hate to be the negative guy, but isn't this the obvious, standard, well known way of building a greenhouse? You want to prevent hot air from escaping, you put up something that contains the air. An actual greenhouse doesn't really rely on "the greenhouse effect" of allowing visual light to pass but being opaque to infrared. It's all about preventing hot air from rising. This can be easily seen in polyethylene windowed greenhouses, which get just as hot as glass greenhouses, even though polyethylene is just as transparent to IR as to visible light.

That part of the piece seemed like something the MIT press office coaxed out of them to get a human interest angle TBH.

Really, most of their improvement over the 2014 version seems to come from the spectrally-selective absorber coating, which is a lot more expensive than bubble wrap. So they say this solution might be ~10x cheaper than existing solar destilling plants, but they also say it will need replacement ~10x as often. So depending on exactly how the numbers work out, this might mean slightly cheaper, more labor-intensive desalinisation plants, but we're not covering any deserts just yet.

I wish I knew how this worked. I'd love to build one myself.

The sponge also converted 20 percent of the incoming sunlight to steam. ... The researchers’ current design builds on a solar-absorbing structure they developed in 2014 ... that was able to boil water to 100 C and convert 85 percent of the incoming sunlight to steam.

Even if they're a little confused about turning energy into matter, it does make me wonder if it's possible to manufacture something cheap, flexible, and durable enough that you could carry a "solar still" blanket for survival purposes. Just unroll it over some moist sand or vegetation, and it would distill and collect water that you could then drink out of a little tube.

> It seems MIT buried the lead. They've found a way to convert sunlight to steam. Should come in very handy in space.

Space has the opposite problem: Remember that vacuum is a perfect insulator. The problem is usually about being able to dump excess heat.

Radiative cooling. Vacuum flasks wouldn't work nearly as well as they do if the internal walls weren't reflective.

Can covering coastal waters with these sheets create artificial/on-demand clouds ? That would be awesome for drought prone areas!

The paper is available on researchgate: https://www.researchgate.net/profile/Hadi_Ghasemi10/publicat...

Original link: www.nature.com/articles/ncomms5449

So, what will this breakthrough mean for desalination efforts?

I assume the idea would be to condense the steam as distilled water, and feed the brine back into the brackish water source. Probably the engineering challenges would be getting the salt water into the evaporator, collecting and condensing the vapor, and removing the "used" brine from the evaporator, and making these components operate continuously.

From the article it sounded like this was an idea that was being considered.

the researchers found the structure heated water to its boiling temperature of 100 degrees Celsius, even on relatively cool, overcast days.

It's not surprising that one could get such a result from solar thermal. Heat pipe based solar collectors have been doing this in cloudy English environs for many years. The really impressive part of this solution is its potential extremely low cost.

any instructions how to replicate?

This really is vapor ware!

Please make sure all comments contribute to the article.

Humor is okay, but should at most be supplementing a more thoughtful comment, and not be the primary contribution of a comment.

Is that in the guidelines?

That's sort of an informal rule-of-thumb a lot follow. Amusingly, the guidelines do specifically say "Please don't submit comments complaining that a submission is inappropriate for the site."

Really, the simplest thing to do is make sure you contribute to discussion in some small way, and then put a rider on for the less contributive aspects you want to voice. That's what the above is really espousing, and while it's not a rule, it does seem to make the discussion flow smoother (and prevents people from jumping in about how you aren't contributing...)

Not in the guidelines, but it is kind of addressed here: https://news.ycombinator.com/newswelcome.html

Specifically: The most important principle on HN, though, is to make thoughtful comments. Thoughtful in both senses: civil and substantial.

The test for substance is a lot like it is for links. Does your comment teach us anything? There are two ways to do that: by pointing out some consideration that hadn't previously been mentioned, and by giving more information about the topic, perhaps from personal experience. Whereas comments like "LOL!" or worse still, "That's retarded!" teach us nothing.

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