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Comment by smolder | Hacker News Reader

They give current solar desalination efficiency as 1.5 kilos of water per square meter. Shouldn't there be a time component?

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They're using Journalist Power Units. You're lucky it's not in houses per year.

My favourite is an old one from the NZ Herald: "6.85kg - the equivalent of nearly seven 1kg blocks of cheese."

How many Libraries of Congress full of water is this?

I love seeing insane units like this in the press. Dishwashers, giraffes, bowling balls, etc. Americans will measure in anything but the metric system.

One such measure stands out to me - they described the accuracy of some computer hardware as “missing one blade of grass while mowing a lawn the size of a football field flying from a helicopter over mile up in the air” (paraphrasing and using quotes to demarcate the interesting bit; not a literal quote).

I guess it’s effective and memorable because even months later, I remember the gist of the accuracy claim (though not the hardware item name)

I am not American, but I love illustrations. A number + an amount of giraffes that illustrate it are better than just the number.

Wouldn't that be rate rather than efficiency?

So maybe it would be better stated as 1.5 kilos per x joules of sunlight (or per area per day average? At the equator?) but as stated I can't make sense of it.

The number is more about the potential productivity of the system across a time period (a full day, I believe), rather than the speed at which it produces purified water at any given moment.

Here is an article from 2020 from MIT using the same units and wording: https://news.mit.edu/2020/passive-solar-powered-water-desali...

I do agree its confusing.

edit: Later in the MIT article they state their device (which is also a 5.8L/m2 system) - "[...] roughly 1-square-meter solar collecting area could meet the daily drinking water needs of one person.

So I will assume the numbers are per day.

edit2: On second thought, the units aren't that confusing. We already use "BTU", for example, to measure air conditioner performance. We just know that means "per hour". Then just the additional complexity of it being based off surface area. "We bought a 6L/m2 solar desalination plant" sounds the same as "We bought a 15,000 BTU A/C unit". Consumer marketing would drop the sizing - "We just bought a 10L desalination plant" and the thing is as big as it needs to be.

Also, do they mean "peak" or "mean"...

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