News for hackers. Stuff that matters.

A comment on Simple, solar-powered water desalination (2020). Parent comment

Re:Simple, solar-powered water desalination (2020) by alpaca128 on Friday July 02, 2021 @06:28AM (#27709832)
Unless you ignore energy sources from the environment you cannot exceed 100% efficiency. And that would be incorrect, applying that same standard to photovoltaic panels would result in infinite efficiency. That doesn't make any sense. Edit: Also, when you take heat/energy from a previous step in the process, you also need to account for the energy put into that previous step. In the end that will again be <100%.

As someone else already pointed out, this would be called Coefficient of Performance. Efficiency is clearly defined and cannot exceed 100% without breaking laws of physics. Call it "3.85 times more efficient than before" or something along those lines and it won't sound like a free energy claim.

[ Parent | on HN ]
Re:Simple, solar-powered water desalination (2020) by Dylan16807 on Friday July 02, 2021 @03:48PM (#27715963)
> applying that same standard to photovoltaic panels would result in infinite efficiency

No it wouldn't. The equivalent for panels would be like... you want to run some number of watts through a diode, and you're using solar panels to collect this power. The diode happens to give off waste light. By aiming this light at your panels, you can recapture most of it back into electricity, and reuse it 2.85 more times.

[ Parent | on HN ]
Re:Simple, solar-powered water desalination (2020) by afiori on Friday July 02, 2021 @01:05PM (#27714077)
the full sentence is:

the [..] device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation.

it seems quite clear how the 3.85 ratio is obtained

[ Parent | on HN ]