Fresh water ban for new cooling plants

The new requirements will be accompanied by changes to tariffs to make electricity sold to air conditioning providers cheaper at night.

New district cooling plants in Dubai will not be allowed to use fresh water and will have to reduce the amount of electricity they draw from the grid in peak hours, the head of the Dubai Electricity and Water Authority (DEWA) said on Monday. District cooling plants are basically giant air conditioners that can cool a building or an entire development up to 40 per cent more efficiently than conventional systems. But they also require vast quantities of water from DEWA's desalination plants. The country is heavily dependent on energy-intensive desalination to provide its fresh water. "District cooling systems are saving energy in one part, while consuming it in another," said Saeed al Tayer, the DEWA chief executive. The majority of the nation's power demand is from air conditioning, and district cooling is seen by DEWA and others as a key way to reduce high power demand that has threatened to overwhelm capacity across the region. The new requirements would be accompanied by changes to tariffs to make electricity sold to district cooling firms cheaper at night and other periods when demand for power was lowest, Mr al Tayer said on the sidelines of a district cooling conference in Dubai. The tariff change will reward firms for implementing "thermal storage" technology that allows the plants to draw electricity at night and produce chilled water for storage and use during the day. According to a decree issued last September by Sheikh Hamdan bin Mohammed, Crown Prince of Dubai, new district cooling plants in the emirate will be required to use treated sewage water, recycled "grey" wastewater or salt water, and to install thermal storage. Mr al Tayer said the law applied to all new plants that were still at the planning stage. "We did a study of the developers. They mentioned that for the next five years, they will need more than 500 million gallons [of water]," he said. "It will cost DEWA billions of dirhams. That's why His Highness Sheikh Hamdan came up with the decree where we ask all district cooling companies to utilise the treated water." The new requirements were not a big hurdle for district cooling firms, said Richard Smith, a technical director at Atkins, a global engineering firm. Several plants in the region already used treated sewage water, he said. "We've done it before. Dubai has a large surplus of [treated sewage effluent] at the moment." Encouraging the growth of district cooling was a key part of DEWA's strategy to reduce the growth in the emirate's power demand, which routinely ranked among the highest in the world, Mr al Tayer said. Power demand in Dubai would grow by at least 6 per cent this year, despite the number of expatriates leaving the country because of the global financial crisis, he said. The company's highest-scenario forecast, developed last year, estimated that demand would grow by an average of 11 per cent per year in the medium term. "There will be an effect, but we don't have a precise figure," he said. "Even if there is one year of slow growth, it will recover. The recovery period will be very fast because the infrastructure is there." Mr al Tayer said the effect of the global crisis was not strong enough for DEWA to consider delaying construction of any of its gas-fired power stations. In an effort to slow demand growth, the utility has implemented education programmes in schools and introduced a new tariff structure last spring that charges customers more for using more than 2,000 kilowatt-hours per month. The tariff change had slowed demand growth by about 1 per cent, Mr al Tayer said. [e-mail]