Study details powerful evaporation
Engineers are working on ways to harvest energy from evaporating water.
New research funded by the US Department of Energy suggests natural water evaporation is a promising alternative source of renewable energy.
The evaluation of the amount of energy that can be harvested from this natural process reveals that natural water evaporation could provide power densities three times that of the wind power.
The researchers report on a model to describe how an evaporation-driven engine affects the evaporation rate and provide predictions on how these energy harvesters could optimally perform in the natural environment.
One of the authors of the new report, Columbia University biophysicist Ozgur Sahin first developed the “evaporation engine” in a 2015 paper.
The process relies on a material that changes size when it fills with water.
Dr Sahin’s tests have used tiny spores that absorb water and get bigger, and when exposed to heat, the water evaporates and the spores shrink.
As the spores swell and contract, they feed a generator that produces electricity from motion, and then harvest energy from that process.
The tiny ‘evaporation engines’ sit on the surface of water, drawing it up from the surface into the device and changing the shape of the spores, which create electricity.
The spores are also connected to shutters that control how much water evaporates, so that the amount of energy generated can be controlled.
The system can even store and release over time to create continuous power.
They estimate up to 325 gigawatts of power is potentially available from evaporation from existing lakes and reservoirs larger than 0.1 km2, which is over 69 per cent of the US electrical energy generation rate in 2015.
The findings indicate the power available from this natural resource is comparable to wind and solar power, yet it does not suffer as much from varying weather conditions.
Finally, the technology can cut the evaporative water losses by nearly half, which might favour the implementation of these energy harvesting systems in regions suffer from periods of water stress and scarcity.