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.
Not great phrasing I agree but the information is there.
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).
I wish journos wouldn't bandy around terminology and statistics they don't understand. It's getting worse.
They just stupidly used watt instead of Wh in the article text.