A billboard outside Lima in Peru serves a dual purpose of drawing water and acting to draw students to the newly established engineering university UTEC
Researchers at the University of Engineering and Technology (UTEC) in Lima and advertising agency Mayo Peru Draft FCB have joined forces to launch a panel that produces clean water from the humidity in the air. The panel is strategically located in the village of Bujama, an area south of the capital city of Lima that is almost a desert, and where some people have no access to clean water.
Lima’s climate is mild, although relative humidity levels are high, rainfall is very low due to strong atmospheric stability. The severely low rainfall impacts on water supply in the city, which originates from wells and from rivers that flow from the Andes. Summer rain, on the other hand, is infrequent, and occurs in the form of isolated light and brief showers. The lack of heavy rainfall arises from high atmospheric stability caused, in term, by the combination of cool waters from semi-permanent coastal upwelling and the presence of the cold Humboldt Current; and warm air aloft associated with the South Pacific anticyclone.
UTEC says it wanted to put “imagination into action” and show that it is possible to solve people’s problems through engineering and technology. “A billboard that produces drinking water from air,” says the billboard up high. And it does what it says on the tin: so far, the billboard has produced over 9,000 litres of drinking water – 96 litres a day.
Despite tough conditions with little rain, air humidity reaches 98%, says UTEC. “The panel traps humidity in the air and transforms it into water. It’s that simple,” said Jessica Ruas, a spokesperson from the university. “There is a lot of water. It is right there in the sea, but it is not suitable for drinking purposes, and costs a lot of money to process it.”Ruas says the system might become a wider solution for the problem. “It doesn’t have to come in the shape of a billboard, but ingenuity is key to development”.
“We want to change the minds of future engineers and inspire them,” said Ms Ruas.
The neighbours have given the billboard a warm welcome. It has become a local attraction for and motorists and an indispensable part of life in the local village.
“We hadn’t realised how big the impact would be,” said Ms Ruas.
The atmospheric water generator (AWG), extracts water from humid ambient air. Water vapor in the air is condensed by cooling the air below its dew point, exposing the air to desiccants, or pressurizing the air. Unlike a dehumidifier, an AWG is designed to render the water potable. AWGs are useful where pure drinking water is difficult or impossible to obtain, because there is almost always a small amount of water in the air. The two primary techniques in use are cooling and desiccants.
The AWG methods used on the billboard in Lima are completely passive, relying on natural temperature changes, and requiring no external energy source. Research has also developed AWG technologies to produce useful yields of water at a reduced (but non-zero) energy cost. On the publicity side, the panel itself seeks to attract the “creative minds that Peru needs” to the young UTEC, which was founded only a year ago and the advert covers the cost of an internal system that was about US$1,200 (£790) to set up.
However there are limits to this kind of system. The rate at which water can be produced depends on relative humidity and ambient air temperature and size of the compressor. Atmospheric water generators become more effective as relative humidity and air temperature increase. As a rule of thumb, cooling condensation atmospheric water generators do not work efficiently when the temperature falls below 18.3°C (65°F) or the relative humidity drops below 30%. The cost-effectiveness of an atmospheric water generator depends on the capacity of the machine, local humidity and temperature conditions and the cost to power the unit.
Lima’s climate is mild, despite being located in the tropics and in a desert. Although classified as subtropical, Lima’s proximity to the cool waters of the Pacific Ocean leads to temperatures much cooler than those expected for a subtropical desert, and can be classified as a cool desert climate.
There are some AWG systems that will run in all environments but the cost of extraction may not be completely free. Because significant input of energy is required to drive these AWG processes, this is sometimes called “trading oil for water”. For Military leaders there is the greatest concern to ensure water sources are always available, even in the most arid of places. One such company in Israeli took up the challenge to ensure water can be readily available, anywhere and at any time. Water-Gen, based in Rishon LeZion, Israel, specializes in water generation and water treatment technologies integrated with tactical military vehicles and ground units.