In some areas, the water use just from cleaning solar panels becomes a serious issue (let alone using more water to cool them). It's not much water to spray on some panels you are experimenting with, but for a large installation it seems like it would be a lot of water.
"When one end of the panel is placed in dirty water, it draws a thin layer of water upwards, which evaporates in the sun, purifying it. By placing the panel inside a glass box, the team collected the evaporated water for use, separating it from the dirty water with a layer of insulation."
3 cm^2 of the material produced 5 ml of water in 2 hours. They don't say what it cost to make.
> it should come as no surprise that the energy you get out by wasting your fresh water isn't as much as the energy you put in to get it in the first place
Agreed, but maybe the effect can be used to alleviate the cost of getting the fresh water? For example, it doesn't cost so much to heat up a building once it's been heated up if it has heat exchangers in its HVAC: the output heat is used to heat up incoming hot air. A wasteful process can be made more efficient with stupid tricks.
> which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 liters per square meter
I would be very interested to see data on this vs. sunlight and climate conditions, in what weeks/month of the year they tested it. I think its effectiveness would be highest at MIT's location from late April to end of September and considerably less in colder/overcast/less sunny weather and winter.
"They have developed a completely passive system that is based on a foam-like material that draws moisture into its pores and is powered entirely by solar heat."
Every day they're using 20.7 litres of water to keep a single panel clean. It's an interesting problem, but I'm certain there's a better way if one were willing to develop better automation.
20 watthours per liter of drinking water is not bad and it's way more efficient than the dehumidifiers. Looks like a great solution even at that slow production rate.
And the cool thing is that the spare "coolness" of the water is released into the air, providing free Air Conditioning while also cheaply heating your water.
>Eventually it’s hoped that buildings will be completely self-sufficient, or “water neutral,” using the same water over and over, potable and nonpotable, in a closed loop.
I can't see that working have they not heard of evaporation? It would work but need a top up. It's a good idea to save water but it may need some fine-tuning for technical reasons and for acceptance by people.
Nice. I've tried searching for it before but clearly didn't get the right combination of keywords. Mostly I've found people using the waste water to pre-heat the supply (which itself is a good idea but doesn't solve the water capacity problem).
I would love that! They make things like that for electrical outlets so you can see how much power things (lamps, clocks, etc) consume. It would be awesome to see the same thing for water. California is in a major drought right now and I'm very curious what in my house uses the most water.
Pretty neat side effect.
reply