[kortex]

It's all about the surface area. The evaporative chiller couples the heat to a much larger volume of air, much more quickly, than a water-air convective heat exchanger. This is due to the high enthalpy of evaporation of water. The hyperbolic towers get an extra boost due to convection.

Once it evaporates to steam, it mixes with more air, which cools it and the steam condenses to fog. But at this point, this heat transfer is of no consequence to the power plant. You can collect this fog without affecting the thermal efficiency of the plant.

But you can't skip that evaporation step because it's the high surface area of the sprayed droplets evaporating that does all the work. You also can't have the collector too close because then you just have a still, and the collector plate heats up from the condensation until it equilibrates. You need the air mixing.

Basically TFA describes a cheap way to get a much larger effective surface area.

[zbrozek]

So... cost, basically? A condenser or heat exchanger will be more capex but consuming fresh water is more opex. And something like these water capture panels might be a way to pick an operating point somewhere in the middle: lose a bit of water, but capture a lot of it for low up-front expenditure?