x Abu Dhabi, UAEFriday 21 July 2017

What the Gulf's cities can learn from the lowly mushroom

Growth is impossible without the right infrastructure below.

Above the erstwhile salt flats of an arid Gulf island, skyscrapers sprout like mushrooms of concrete and steel. Signifying high-density human habitation in one of the harshest environments on Earth one severely lacking in water they are a wonder of the modern world. There is very little natural about the cities of the Gulf region. In their extreme dependence on artificial fresh-water sources, they are an ecological phenomenon unique in human history.

But just as mushrooms are the fruit of a larger organism lying below ground, the skyscrapers are merely the most eye-catching manifestation of a gigantic urban infrastructure that in a few short decades has transformed the landscape here. The most vital part of that is the power and water network that makes life possible in Abu Dhabi and other modern cities strung out along the Gulf and Red Sea coasts.

It was the vast oil and gas reserves of the emirate of Abu Dhabi that drew millions of people to live and work here. It is those same energy resources that sustain the recently swollen local population by fuelling the world's biggest concentration of water desalination plants. The fungal mycelium, or web-like part of the organism that pushes up mushrooms, requires a power source usually decaying organic matter that provides a store of chemical energy.

Desalination plants also need power to vapourise water or push it through porous membranes. In the case of Abu Dhabi's huge water projects, power is needed on a massive scale. At present, that energy also comes from buried organic matter: oil and gas. Gas has been the fuel of choice for Abu Dhabi's combined electricity generation and water desalination plants, because it burns more cleanly than oil and is valued less as an export commodity. But in the case of gas shortages, which have developed every summer in recent years, oil can also be used as fuel for de-salting water. So it is perhaps not too surprising that in this country, oil is cheaper than drinking water.

Desalination can also be a natural process, powered by the sun. Not much of that takes place within the desert confines of the Arabian peninsula, but on a global scale the sun desalinates water all the time by causing it to evaporate from the oceans, lifting the vapour high into the atmosphere and depositing it on land as rain or snow. Eventually, the water makes its way back to the world's seas and oceans under the influence of gravity, picking up mineral content as it flows.

With less than 100mm of rainfall per year, Abu Dhabi has had to improvise to sustain its hugely expanded and dense population. The nomadic tribes historically survived by tapping the limited groundwater resources. Those tribes had to move around, if only because they would exhaust the local water supply if they stayed in one place for too long. Settled city life in Abu Dhabi and the rest of the Gulf region is a recent phenomenon that was scarcely possible before the advent of commercially viable large-scale water desalination technology. That did not emerge until the 1980s, and began to flourish worldwide only in the 1990s, according to the International Desalination Association, based in Topsfield, Massachusetts.

Today Abu Dhabi produces about 2.8 billion litres of desalinated water every day. It plans to double that over the next decade at a cost of roughly Dh73 billion (US$20bn). Dubai has a comparable programme to expand its desalination capacity. But in future, not all the energy for desalination will come from fossil fuels. The UAE's civilian nuclear power programme is linked as much to the projected water demand as to expected growth in electricity consumption. Indeed, power generation and water desalination are inextricably linked here, as it is more cost-efficient to build and operate large integrated power and water projects than to develop separate facilities for each.

Solar power could also figure prominently in future water supply, although it may take years, perhaps decades, to develop on a scale large enough to be cost-effective. Still, there are some clear advantages to using sunlight the one energy source that Abu Dhabi has more of than oil to produce fresh water. One technology, concentrating solar power (CSP), uses mirrors and lenses to boil water, producing steam to drive a turbine. A CSP plant could desalinate water as a by-product of generating electricity. Minus the turbine, that is very much how nature arranges water desalination on a global scale.

The Gulf region's cities may be largely artificial - but then again, aren't all cities? Still, just as mushrooms are products of green meadows and forests, their skyscrapers tower above well-watered cityscapes generously endowed with green spaces. Could the ever expanding man-made water projects one day turn much larger tracts of desert green? In terms of saving the planet and feeding the mass of people here, that could be energy well spent.

@Email:tcarlisle@thenational.ae