Is humidity usually high by the ocean? Would it be more efficient to pull water out of the air? Maybe take advantage of low night temps to collect dew?
Simple, solar-powered water desalination
111–120 of 205 posts
Re: Simple, solar-powered water desalination
#112This topic always reminds me of the opening scene[1] from Waterworld where a guy on a raft out in the sea passes his urine through some kind of filter that turns it into drinkable water, and drinks it. I was a little kid when I watched it and wondered why he would drink his own urine when he was surrounded by such vast amounts of water. With this type of technology, maybe he wouldn't have had to do something so gross…
Given the agricultural issues in that movie, perhaps the purification device was intended more to collect and concentrate the urea than to purify the water. But that assumes the scriptwriter would have thought of that, which may be a stretch, given that Earth has insufficient water to cover all landmasses to a depth of 7 km. That would require about 3.6 billion cubic kilometers more water than already exists in the o…
On a long enough timeline, especially with more energetic atmospheric conditions, isn't it possible for the land to redistribute itself more uniformly from the various forms of erosion to the extent that it's all submerged?
Re: Simple, solar-powered water desalination
#113A lot of lithium batteries are making their way onto both sailboats and yachts. With significant advantages come equal disadvantages, and those disadvantages are the risk of potential battery fires, which only a Class D fire extinguisher can snuff out. The Dive boat fire in San Diego, where 34-persons perished, is one example.
You don't need batteries to run a reverse osmosis desalinator from solar panels; you can run the desalinator when the sun is shining and store the water. I'm surprised boats are already moving to lithium. I wonder if it would be worthwhile to tow the batteries in a separate buoy behind the boat?
> I'm surprised boats are already moving to lithium.
When the alternative is a bank of lead-acid batteries with effectively ~50% usable capacity and poor charge efficiency, at least for cruisers effectively living at sea off solar power, it's not surprising at all.
Re: Simple, solar-powered water desalination
#114Earlier quoted context omitted.
Kinda explained in the 9th graf: > Unlike some desalination systems, there is no accumulation of salt or concentrated brines to be disposed of. In a free-floating configuration, any salt that accumulates during the day would simply be carried back out at night through the wicking material and back into the seawater, according to the researchers.
So the salt is just going back into the ocean. How is that different from other systems, they end up dumping the salt somewhere.
There's no difference. Except that the processing and shipping of ions is passive / much easier. Contrasted with large permeable membrane plants that have to burn power to push all that brine out into the ocean.
Re: Simple, solar-powered water desalination
#115A thunderfoot video waiting to happen
While we wait are there any sites where people actually intelligently discuss this article?
It seems like a 100 year old tech they are trying to optimise. I feel like random optimisations would mean there are no advances to get here.
But it is possible using computer simulations they could do something of value. Have they?
Re: Simple, solar-powered water desalination
#116>> 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area. So a football field could collect around 8,000 gallons of water per hour. Let's say you can get 5 hours of good sunlight per day = 40,000 gallons of water. >> The team’s demonstration device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation. >> Theor…
> So a football field could collect... 40,000 gallons of water. How many swimming pools of water is that?
40,000 gallons is approximately 150,000 L, while an Olympic pool is in the area of 1,000,000 L.
So around 0.15 Olympic pools — roughly, a football field would fill an Olympic pool in a week.
Re: Simple, solar-powered water desalination
#117A lot of lithium batteries are making their way onto both sailboats and yachts. With significant advantages come equal disadvantages, and those disadvantages are the risk of potential battery fires, which only a Class D fire extinguisher can snuff out. The Dive boat fire in San Diego, where 34-persons perished, is one example.
Conventional boat fuel burns fiercely, too.
Re: Simple, solar-powered water desalination
#118Earlier quoted context omitted.
I guess it's not really surprising for American engineers. Food and drink are measured in Imperial units. Technical doodads are measured in metric. You don't really need them to be compatible in this case: even though it appears that you're talking about multiples of units of length, you don't really compare them. You're not going to do the calculation that this is "1.58 micrometers per second" or ".447 feet per day"…
Given the increasing popularity of 500 mL and 1 L units of bottled water, and the ubiquity of the 2 L HDPE beverage bottle, I think it would have been safe to measure the potable water output in liters. About the only things still sold by whole gallons any more are milk, water, iced tea, and lemonade, in the 1 gal jugs, or water in the 5-gal water-cooler jugs. I'm more confused by the efficiency numbers exceeding 100…
Servings of beverages in the US are still mostly in imperial measures. A can of soda is 12 ounces; so are most bottles. Beer in restaurants is usually a pint; if not, they'll specify ounces. A Starbucks venti is so called because it's 20 ounces; a tall is defined as 12 ounces. And American recipes still use cups and tablespoons (where the rest of the world has gone almost exclusively to grams, and not volume at all).
The soda industry went to 2 liter bottles back when the country tried to go metric, and it stuck. But most things haven't, including the individual serving sizes. So people never really got the feel for anything smaller than a liter.
Re: Simple, solar-powered water desalination
#119"than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area." Units, people. Units. Be imperial. Be metric. Hey! Be both!
I guess it's not really surprising for American engineers. Food and drink are measured in Imperial units. Technical doodads are measured in metric. You don't really need them to be compatible in this case: even though it appears that you're talking about multiples of units of length, you don't really compare them. You're not going to do the calculation that this is "1.58 micrometers per second" or ".447 feet per day"…
> Technical doodads are measured in metric.
Not always. I would wager that you are using an electronic device whose circuit board was dimensioned in 'mils', which are not millimeters but thousands of an inch.
Re: Simple, solar-powered water desalination
#120Earlier quoted context omitted.
New york city is 468.484 sq mi in size... so we're talking about covering 1 to 2% of it in these panels... I'm pretty sure that much roof space is available. Of course it probably makes more sense economically to do it offshore or just have a giant field somewhere outside of NYC and pump the water in, but you could find the space inside the city if you really wanted to.
I think you'd lose a bit of efficiency have to pump circulated seawater to the roof tops to not only provide water to desalinate, but also to flush out the accumulated brine overnight.
Those skyscrapers teem with occupants, each with a bladder, each one a source of saline. The spare water and power we use for growing cucumbers in the hydroponic gardens. The waste brine we use for picking those gherkins, which makes the ideal beer-time snack for those occupants as they re-fill their bladders...