Masdar City, the carbon-neutral development on the outskirts of the capital, is facing a major challenge in obtaining a supply of fresh water that meets the city's tough environmental specifications. The city's developers are exploring the use of geothermal energy to help desalinate an underground aquifer, Masdar officials said. Masdar is looking for alternative sources of supply after discovering that shallow water reserves just under the city, located near Abu Dhabi International Airport, contained more salt than Gulf water and could not be converted into fresh water efficiently with solar panels and other renewable energy sources, said Dr Ameena al Kulaib, the manager of the water department at Masdar.
"With this kind of salinity we cannot say we have a viable treatment solution already," Dr al Kulaib told a MEED conference in the capital last week. "We cannot just use a sustainable solution without considering commercial viability." The city construction site and Masdar's temporary headquarters were supplied with water from Abu Dhabi Distribution Company (ADDC), she said. ADDC gets its water from the Abu Dhabi Water and Electricity Authority, which uses the heat from huge fossil-fuel power stations to desalinate water from the Gulf.
The utility's multi-stage flash desalination technology, which is in use in most of its plants, produces water that is among the most carbon-intensive in the world. "Energy is the biggest concern everybody has," Dr al Kulaib said. "Water is the biggest consumption of power." Masdar was keeping track of the water it took from ADDC and would look to offset the carbon used later, possibly by investing in more cost-effective desalination elsewhere in the emirate, said Jay Witherspoon, an operations director and technology leader at CH2M Hill, a consultancy under contract with Masdar.
"By the time the city is built out, we will be carbon-neutral," Mr Witherspoon said. In September, Masdar announced it would drill several geothermal wells deep into the Earth in search of heat to help power cooling systems and generate electricity. The company has drilled almost to a depth of 2,500 metres and, if it finds heat of between 100°C and 120°C, it will use the wells to preheat the salt water and then convert it into fresh water on the surface with renewable sources, Mr Witherspoon said.
"Using a geothermal source allows it to be more cost-effective," he said. Mr Witherspoon said if the experiment were successful, Masdar could eventually drill up to six such wells, supplying the city with most of the water it needed for cooling and other needs apart from drinking, and extra energy for the city. Masdar is also looking to drastically cut water consumption of its homes and businesses from normal UAE levels, and make greater use of recycled wastewater, Dr al Kulaib said.
The Environment Agency - Abu Dhabi has estimated that each person in the emirate uses 550 litres of water a day but Masdar wants to reduce use to 105 litres a day, below levels in Germany and Syria, by using low-flow water fixtures and encouraging more responsible personal use, Dr al Kulaib said. The technology will be tested this summer when the first students and faculty of Masdar Institute move into the new campus, she said.
"We can achieve this reduction by using really smart fixtures and fittings without interrupting the comfort of the person," Dr al Kulaib said. She said the city would also use treated wastewater for landscaping and district cooling, and was considering it for personal use apart from drinking, such as flushing toilets. Masdar is also exploring options for recycling the brine and residue left behind after water is desalinated, Dr al Kulaib said. Most desalination plants in the region discharge the residue back into the sea, a practice experts say damages the ecology of the Gulf.
cstanton@thenational.ae
