DEWA considers Jebel Ali hybrid option
- From: Vol 4, Issue 12 (December 2003)
- Category: General
- Region: Middle East
- Country: United Arab Emirates
- Related Companies: Doosan Heavy Industries, Mott MacDonald and Ondeo
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Mott MacDonald is to carry out a pilot plant study. The main question is can RO handle the harsh gulf waters?
The Dubai Electricity & Water Authority (DEWA) is to investigate the possibility of developing a hybrid RO-MSF desalination plant at the proposed Jebel Ali L2 station. The authority has appointed the UK’s Mott MacDonald for a study and to prepare tender documents for a pilot SWRO plant to be installed at the Jebel Ali site.
The tender for the 5-10m3/hr demonstration plant will be issued later this month and contract award is scheduled for February 2004. The plant will be operated for a period of 52 weeks and is intended to provide information on how the RO process copes with the notoriously difficult Persian Gulf waters.
The main advantage of hybrid plants is the flexibility they offer for coping with the varying demand for electricity and water. Conventional co-generation plants can experience problems when there is little or no demand for electricity but the demand for water is high (for example, during gulf winters).
If the co-generation plant is scaled down, it produces little or no waste heat for the MSF distillers and auxiliary boilers have to be started. If an adjacent RO unit is used, water can be produced separately, meaning that the boilers need not be started, fuel is used more efficiently and water production costs are lower.
Several countries in the gulf are considering the use of hybrid RO-MSF configurations. The largest example is the Fujairah Phase 1 power and desalination plant at Qidfa, which will produce 285,000m3/d of water on an MSF basis and around 170,000m3/d using RO. The RO plant has been built by Ondeo Degrémont as subcontractor to Korea’s Doosan Heavy Industries. The client is the Union Water & Electricity Company (UWEC).
However, it is by no means certain that DEWA will choose to include a hybrid configuration in the forthcoming tender for Jebel Ali L2. “The waters at Jebel Ali are much more difficult for RO than at Fujairah”, said Olaf Goebel, desalination project manager with Lahmeyer International, DEWA’s consultant for the first L station. Seawater intake at Fujairah is from the much less aggressive Gulf of Oman while the Jebel Ali complex, 30km west of Dubai, lies on the Persian Gulf. Additionally, the Qidfa RO plant is not fully operational yet and is thought to have experienced water quality problems during testing.
“It is not always easy to quantify the advantages of a hybrid plant. Where RO is possible, [a hybrid configuration] needs to be investigated but at sites with very low fuel costs, distillation processes might be competitive”, added Goebel. “There are too many factors which can influence the water generation costs”.