Desalination really seems like the poster child for the Low Tech Magazine's philosophy of removing intermediaries - why put solar into a solar panel that runs a machine to desalinate, when the...
Desalination really seems like the poster child for the Low Tech Magazine's philosophy of removing intermediaries - why put solar into a solar panel that runs a machine to desalinate, when the light could desalinate directly? That saves on conversion efficiencies, and it saves material (direct solar means no PV costs, only glass). There's some incredibly simple passive desalination tech out there.
That said, PV costs are dropping like a rock, so maybe that's not the biggest concern - glass for direct solar can get dirty and destroy efficiency, whereas solar panels can be potentially more reliable, and an electrical field system could be potentially lower maintenance.
If I'm understanding correctly, you're talking about using evaporation from direct sunlight, which would produce distilled water. Unfortunately, distilled water isn't good for drinking water, as...
If I'm understanding correctly, you're talking about using evaporation from direct sunlight, which would produce distilled water.
Unfortunately, distilled water isn't good for drinking water, as it removes the calcium and magnesium we need from water. It also leeches minerals from the body including the teeth.
MIT engineers have built a new desalination system that runs with the rhythms of the sun.
The solar-powered system removes salt from water at a pace that closely follows changes in solar energy. As sunlight increases through the day, the system ramps up its desalting process and automatically adjusts to any sudden variation in sunlight, for example by dialing down in response to a passing cloud or revving up as the skies clear.
Because the system can quickly react to subtle changes in sunlight, it maximizes the utility of solar energy, producing large quantities of clean water despite variations in sunlight throughout the day. In contrast to other solar-driven desalination designs, the MIT system requires no extra batteries for energy storage, nor a supplemental power supply, such as from the grid.
For infrastructure, there are two main costs, the cost to build the plant (capex) and the cost to operate it (opex). An off-the-grid, solar-powered plant has no opex for fuel or electricity....
For infrastructure, there are two main costs, the cost to build the plant (capex) and the cost to operate it (opex). An off-the-grid, solar-powered plant has no opex for fuel or electricity. That’s good! But what about the other costs?
On the capex side, I wonder how expensive this system is to build? Going without a grid connection or batteries reduces the cost to build, but also decreases output, since it only runs during the day. So the question is whether the savings is worth it?
Since they’ve only built a prototype, they likely don’t know that yet. But it looks like they’re going to give it a go:
“While this is a major step forward, we’re still working diligently to continue developing lower cost, more sustainable desalination methods,” Bessette says.
“Our focus now is on testing, maximizing reliability, and building out a product line that can provide desalinated water using renewables to multiple markets around the world," Pratt adds.
The team will be launching a company based on their technology in the coming months.
For another company with a similar strategy (but to produce natural gas rather than water), see Terraform Industries.
I've always wondered (not enough to do the research yet) about the sustainability and lifecycle of membrane-based desalination. You'd think those fragile plastic layers wouldn't last forever, and...
I've always wondered (not enough to do the research yet) about the sustainability and lifecycle of membrane-based desalination. You'd think those fragile plastic layers wouldn't last forever, and might come with microplastics issues.
As a way to make brackish groundwater consumable in places that otherwise wouldn't have the scale or resources for larger scale desalination, it's interesting. But you've still got to pump, distribute, and sanitize it. I can't see that it's more cost-effective than relocating people closer to resources, and not overconsuming or contaminating groundwater in the first place.
I’m not so sure about that cost comparison. For example, drilling a deeper well might be expensive, but not compared to abandoning the buildings it supplies and building new housing somewhere...
I’m not so sure about that cost comparison. For example, drilling a deeper well might be expensive, but not compared to abandoning the buildings it supplies and building new housing somewhere else. And as the cost of real estate rises, it becomes more worthwhile to spend money to protect it.
Abandoning farmland (at least for water-intensive crops) and shipping food in will happen first; this is effectively a way of importing water. Maybe they could put in solar panels instead?
But the price of real estate can also work the other way, like in rust-belt cities or maybe rural Japan or Italy. As people leave the prices drop and make it easier to abandon.
So what this gets at is that some housing in some locations is much more desirable than others, and it all depends on how desirable it is. Even if you don’t want to live there, if someone else does, it’s hard to pass up the opportunity to sell it to them and get your money out.
Moving people out of cheap, substandard housing, if they have somewhere to go, might be more feasible?
Desalination really seems like the poster child for the Low Tech Magazine's philosophy of removing intermediaries - why put solar into a solar panel that runs a machine to desalinate, when the light could desalinate directly? That saves on conversion efficiencies, and it saves material (direct solar means no PV costs, only glass). There's some incredibly simple passive desalination tech out there.
That said, PV costs are dropping like a rock, so maybe that's not the biggest concern - glass for direct solar can get dirty and destroy efficiency, whereas solar panels can be potentially more reliable, and an electrical field system could be potentially lower maintenance.
If I'm understanding correctly, you're talking about using evaporation from direct sunlight, which would produce distilled water.
Unfortunately, distilled water isn't good for drinking water, as it removes the calcium and magnesium we need from water. It also leeches minerals from the body including the teeth.
From the article:
For infrastructure, there are two main costs, the cost to build the plant (capex) and the cost to operate it (opex). An off-the-grid, solar-powered plant has no opex for fuel or electricity. That’s good! But what about the other costs?
On the capex side, I wonder how expensive this system is to build? Going without a grid connection or batteries reduces the cost to build, but also decreases output, since it only runs during the day. So the question is whether the savings is worth it?
Since they’ve only built a prototype, they likely don’t know that yet. But it looks like they’re going to give it a go:
For another company with a similar strategy (but to produce natural gas rather than water), see Terraform Industries.
I've always wondered (not enough to do the research yet) about the sustainability and lifecycle of membrane-based desalination. You'd think those fragile plastic layers wouldn't last forever, and might come with microplastics issues.
As a way to make brackish groundwater consumable in places that otherwise wouldn't have the scale or resources for larger scale desalination, it's interesting. But you've still got to pump, distribute, and sanitize it. I can't see that it's more cost-effective than relocating people closer to resources, and not overconsuming or contaminating groundwater in the first place.
I’m not so sure about that cost comparison. For example, drilling a deeper well might be expensive, but not compared to abandoning the buildings it supplies and building new housing somewhere else. And as the cost of real estate rises, it becomes more worthwhile to spend money to protect it.
Abandoning farmland (at least for water-intensive crops) and shipping food in will happen first; this is effectively a way of importing water. Maybe they could put in solar panels instead?
But the price of real estate can also work the other way, like in rust-belt cities or maybe rural Japan or Italy. As people leave the prices drop and make it easier to abandon.
So what this gets at is that some housing in some locations is much more desirable than others, and it all depends on how desirable it is. Even if you don’t want to live there, if someone else does, it’s hard to pass up the opportunity to sell it to them and get your money out.
Moving people out of cheap, substandard housing, if they have somewhere to go, might be more feasible?