+ Solar power could be the answer for desert aquifers

Is there finally a case for large-scale solar desalination?

I was working in Algeria earlier last year on the site investigation for a gas pipeline project. Our route to work was a two hour journey, part on highway and mostly across the rocky Sahara desert. Next to the highway a new water pipeline was being constructed by a Chinese construction company.

Now I am not quite sure how the pipeline system worked but it seemed to me that they were pumping water from aquifers in the north further south into the desert, to a resort which had now exploited its water past their own safe level of depletion. It is almost the perfect storm for an unsustainable existence.

Whilst bumping along across the desert it came home to me that there was an opportunity to close the cycle on this water and energy problem. Solar power really ought to be used to desalinate water. All this abundant solar energy could be focussed onto delivering the most precious of commodities in the desert, water.

There has to be a case for reducing consumption, recycling and reusing water wherever possible but there is an overall increasing deficit. The last place we need to encourage settlement is in the central Sahara but it inevitably will where there are oil and gas energy resources.

If saline water could be brought into the deserts from the coast and solar power used to clean it up in slow time it could then be used to recharge the aquifers which could store the water safe from the effects of evaporation. Water can then be drawn off from the aquifer at wells as and when people need. There is a case for coupling technologies and there may be some synergies between solar desalinated water and algae to biofuel.

Algae grows best in saline water and high levels of sunlight. It does not take up large amounts of clean water, it digests CO2 and nutrients from waste water and can operate on poor quality land. Furthermore it generates biomass rich in phosphates which can be good for agriculture.

Photography credit: ©David Millngton Photography Ltd