DUBAI //A developer says a high-tech treatment system has cut water use by a third at one of its district cooling plants.
The water, enough to fill almost four Olympic-sized swimming pools, was saved over five months. The savings highlight opportunities that go mostly unrealised across the Emirates.
Limitless, the developer behind The Galleries office and residential complex in Dubai, installed the patented water-treatment system in November last year.
The company then compared the water consumption of its chiller plant in the first five months of this year with the same period last year, and said it found water use was down by 33 per cent.
District cooling works by chilling water in a central plant then distributing it through pipes to buildings. Inside the buildings, the pipes are connected to conventional air-conditioning units that allow the cooler temperature of the water to chill the air passing through them.
The Limitless plant uses water cooled to a temperature of about 5°C. It services about 800,000 square feet of space.
The newly installed device, known as the Dolphin, is produced by the US company Clearwater Systems. It sends electromagnetic pulses into the cooling plants' water. The waves kill water-borne bacteria and prevent corrosion and scaling, eliminating the need for chemicals.
The lack of chemicals allows the water to stay longer in the system before it must be discharged as waste, said William Skopek, senior mechanical engineer at Limitless.
The waste water can be cleaned and used for irrigation.
"Any time you have an open chilled-water system, the water can only stay in the system a certain length of time," Mr Skopek said.
If chemicals are added to the water in the cooling system, the water can circulate up to five times. But it can circulate up to eight times when treated with electromagnetic pulses, he said.
This also reduces the amount of waste water produced by the cooling system. A chemical system's outflow must be taken for treatment by tankers, requiring two or three tanker visits a day.
The water produced by the new system is sent to the development's small water-treatment plant, where it is cleaned, together with other types of waste water, and used for irrigation. More than three million litres have been recycled for irrigation since the system was installed.
Mr Skopek said he was not allowed to disclose the cost of the system, but it would pay for itself within two years.
"So far, it is already a good return on investment," he said, adding the decision last year by the Dubai Electricity and Water Authority (Dewa) to start applying a fuel surcharge gave a higher value to the efficiency savings.
Saving water can also have a positive effect on the environment. Desalination plants burn fossil fuels to turn seawater into water for drinking, irrigation and district cooling. The process releases greenhouse gases that contribute to global warming.
Most efforts to improve the efficiency of cooling systems have focused on reducing their energy consumption, rather than amount of water used.
Air conditioning takes between 60 and 70 per cent of the country's energy production. The effect of cooling systems on water use is less well understood.
Limitless is the fourth in the UAE to install the system, said Dan Mizesko, managing partner of US Chiller Services, which distributes the system in the region.
"In the Gulf region, we have installed it in Saudi Arabia, the UAE and Qatar on 200,000 tonnes of cooling systems," Mr Mizesko said. Shopping malls, convention centres, office towers and district cooling plants are among the clients.
The Dolphin system is popular in the US, where there are 4,000 installations, he said.
"It is popular anywhere in the US where water savings are a priority," Mr Mizesko said.