5 ms·

> requires only 20 watts of power per liter. So if you want a liter, you have to supply 20 watts. For how long? Forever? Does the water instantly become turbid

> requires only 20 watts of power per liter. So if you want a liter, you have to supply 20 watts. For how long? Forever? Does the water instantly become turbid when power is removed? Tsk, tsk, MIT. I would have thought an MIT journo would know what a watt is.

soVeryTired 5y ago
> Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter. Not great phrasing I agree but the information is there.
- qayxc 5y ago
  Nah, still doesn't make any sense either way. Watts is a measure of power, not energy. The amount of power (given they use a pump and electrodialysis) shouldn't depend on the volume. Energy OTOH does. So either their device requires 20W of power - which sounds reasonable as the image shows a <100Wp solar panel next to it - and the volume figure is meaningless. Or the author left out crucial context (e.g. is the power draw correlated with the speed, i.e. 20W @ 0.3l/h). The amount of energy would be 67Wh/l regardless given those numbers. It's just a confused mix of performance (processed volume per hour) and power requirements (which is independent of volume and should only depend on the performance).
- denton-scratch 5y ago
  The trailing "per liter" seems the problem: I think maybe what they mean is that 20W gets you 0.3 liters per hour? So their machine produces 0.3 liters per hour, and draws 20W? I wish journos wouldn't bandy around terminology and statistics they don't understand. It's getting worse.
  - SamBam 5y ago
    It isn't, though, because that would be 60Wh per liter, but the video actually specifies it's 20Wh per liter. They just stupidly used watt instead of Wh in the article text.
aaron695 5y ago
davelondon 5y ago
When someone uses watts as a unit of energy, they mean watt hours. It's very common.
- davelondon 5y ago
  ... and in the video they specify 20Wh/L.

soVeryTired 5y ago

> Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter. Not great phrasing I agree but the information is there.

qayxc 5y ago
Nah, still doesn't make any sense either way. Watts is a measure of power, not energy. The amount of power (given they use a pump and electrodialysis) shouldn't depend on the volume. Energy OTOH does. So either their device requires 20W of power - which sounds reasonable as the image shows a <100Wp solar panel next to it - and the volume figure is meaningless. Or the author left out crucial context (e.g. is the power draw correlated with the speed, i.e. 20W @ 0.3l/h). The amount of energy would be 67Wh/l regardless given those numbers. It's just a confused mix of performance (processed volume per hour) and power requirements (which is independent of volume and should only depend on the performance).
denton-scratch 5y ago
The trailing "per liter" seems the problem: I think maybe what they mean is that 20W gets you 0.3 liters per hour? So their machine produces 0.3 liters per hour, and draws 20W? I wish journos wouldn't bandy around terminology and statistics they don't understand. It's getting worse.
- SamBam 5y ago
  It isn't, though, because that would be 60Wh per liter, but the video actually specifies it's 20Wh per liter. They just stupidly used watt instead of Wh in the article text.

aaron695 5y ago

davelondon 5y ago

When someone uses watts as a unit of energy, they mean watt hours. It's very common.

davelondon 5y ago
... and in the video they specify 20Wh/L.