After off-grid electricity, what chance off-grid water?

Imaduddin Ahmed FT Kigali to Musanze

Early morning mist over the hills of northern Rwanda. Harvesting water from droplets in the air offers a low-cost solution to local water shortages © Imaduddin Ahmed

Financial Times | 31 July, 2017
Innovative solutions bring the prospect of accessible water to the isolated poor
By Imaduddin Ahmed

 

Fifty-one million people lack access to safe water in the core East African Community member states of Tanzania, Kenya, Uganda and Rwanda, according to WaterAid. Over 13,000 children under five die each year of diarrhoeal diseases caused by poor water and sanitation in these states.

Yet, with emerging innovations in water condensation, these and other similar statistics could soon be confined to the history books.

People on the dry hills above Lima, in Peru, for example, harvest their morning fog. Walls of vertically stretched nets between bamboo poles catch droplets that otherwise fail to form rainfall. Gutters below carry the flow of drops to storage containers. Each net contributes 200 to 400 litres a day. The water is not potable, but is useful for small-scale farming, washing and cooking.

During the dry seasons, Rwanda’s Eastern Province district of Ngoma has similar humidity levels to those in Lima. According to census data, Ngoma has one of the lowest rates of access to improved water in the country. Nationally, almost three-quarters of households collect water from improved sources, almost half have to travel more than half an hour to fetch it, and only 11 per cent have water on their premises.

It would not take much to find out whether Ngoma and other parts of Rwanda could achieve water yields from cloud-catching nets like those in Lima. This low-cost innovation should also work in humid parts of Uganda, Kenya and Tanzania. Even if the water was not potable, it would help prevent the cannibalisation of drinking water for other uses.

For more arid environments, researchers at the University of California, Berkeley and the Massachusetts Institute of Technology have found another electricity-free way to condense vapour. Metal-organic frameworks in the form of zirconium fumarate crystals pull moisture from the air into their large pores and feed water into a collector, in response to low-grade heat from natural sunlight.

A kilogramme of metal organic framework harvests 2.8 litres a day at 20 per cent humidity. But at $150 a kilogramme of zirconium, the solution has not yet been developed into a cost effective one.

Veragon, a London-based company, says it has a commercially viable solution for condensing potable water that is being sold to the Italian military, Nato and the UN World Food Programme for operations in the Philippines, Afghanistan, Libya and Senegal, and to commercial distributors in Nigeria, Ghana and Oman.

The company manufactures in Italy “atmospheric water generators” that filter air, condense vapour on cooled panels, oxidise contaminants, add minerals and disinfect the condensed water using ultraviolet light. Inspiration came to the founder, an oral surgeon, on a humanitarian mission in Haiti. While contemplating the absence of clean water, he noticed that the air-conditioning was leaking water that appeared clean.

Atmospheric water generators could make sense for governments seeking to provide access to safe drinking water to dispersed citizens in challenging, hilly geographies where the costs of piping and pumping from mainstream treatment plants are high. A 1,000 litre capacity unit in Rwandan conditions is expected to yield 680 litres daily — enough to cater for the needs of a village of 350 people. €50,000 will purchase a unit that consumes 8-12kWh of energy — a feasible amount for solar panels to provide, as well as for batteries.

Arizona-based Zero Mass Water currently does sell solar-powered units that produce 2-5 litres of water a day, enough for one or two individuals. But at $3,700 a unit, they cost more than five times the mean annual Rwandan gross domestic product per capita.

While solar home systems have conquered economies of scale for rural electricity generation, it remains to be seen whether the same can be achieved with household systems for atmospheric water generation. Micro-grids serving multiple households for now seem the better option.

With upcoming general elections in Kenya and Rwanda, would not one obvious way to canvas rural votes be to promise access to drinking water? There is water in the air. It offers more than a drop to drink.

Imaduddin Ahmed is pursuing a PhD in the economics of rural infrastructure at The Bartlett, University College London. He assisted the Rwandan government in negotiating infrastructure projects for four years.

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