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Reverse Gear

Membrane tech gains ground on thermal desalination.

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ANALYSIS

The demise of thermal desalination in the Middle East has long been predicted but the technology has proved surprisingly resilient in the face of the challenge from the less energy intensive membrane desalination process, aka reverse osmosis (RO), which is by far the technology of choice outside of the Gulf.

Thermal desalination, which heats seawater to produce steam before condensing the purified water, is the most popular method of desalination in the Middle East, due to the abundance of oil and gas which is used as the main source of energy for the process.

One of the reasons for this is the high number of large (over 100,000 m3/day) desalination plants in the GCC, and at such capacities, thermal desalination is a proven technology. Lower primary energy cost in the GCC has further underpinned the use of thermal desalination processes such as Multi-stage Flash (MSF) and Multi-effect Distillation (MED).

However RO is rapidly gaining a greater toehold in the market as countries in the Middle East, particularly the GCC, look for ways to cut back on energy consumption to cope with the demands of rapid economic and demographic growth.

Reversing the trend

The shift in momentum towards reverse osmosis is in line with a move away from building huge desalination plants, says Christian Wee, Global Business Development Director at Aqualyng, a company that has delivered EPC and BOOT solutions to the global desalination industry for 20 years.

Though historically, the Gulf has been the main market for thermal desalination, at the moment all forecasts show that reverse osmosis will take more and more market share, he says. Part of the reason for this is the increasing focus on smaller plants.

“With more focus on medium sized plants, some of the benefits of thermal plants are no longer there, and that helps grow the RO market share,” he says.

Added to this RO is by far the most cost effective technology for standalone desalination plants, which are becoming more and more common in the Gulf, and there are an increasing number of desalination plants using a hybrid of both thermal and reverse osmosis technology due to the cost benefits they offer.

“For standalone water projects, reverse osmosis is definitely the dominant technology,” says Myron Van Ert, Regional Executive of GE Water & Process Technologies for Middle East & Africa. “For the large combined power and water projects, thermal solutions will still be prevalent in the region.

“But, as witnessed in the overall global desal market, RO has clearly demonstrated its cost effectiveness both from a capex and opex perspective. The noted increase in hybrid projects reflects this shift, and the likelihood is favourable that RO will maintain its growth due to its distinct cost advantage and continued technological advances.”

Gulf states have seen domestic energy demand grow rapidly in lockstep with their economies. Saudi Arabia, for example, burns ever more oil in its power and desalination plants which could otherwise be sold on the international market. This trend has put greater pressure on budgets and sharpened the focus on finding cheaper and more energy efficient ways of producing power and water.

These sustainability drives are playing a huge part in the transition towards reverse osmosis which consumes substantially less energy compared to thermal desalination, explains Roland Ang, Managing Director, Business Development for Middle East, Hyflux.

“Advances in membrane technology and scalability also means the cost of membranes has become more affordable and we see a growing trend towards energy efficient methods that couple ultrafiltration in the pre-treatment process with seawater reverse osmosis for desalination,” he says.

“Membrane technology is also flexible, and can also be configured and modularised to meet changes in water demand and specifications, making it suitable for a wide-range of industrial and municipal needs.”

The tide may have turned firmly in favour of RO, though not quite as fast as some had predicted, says Kshitij Nilkanth, Program Manager, Energy & Environment Practice, Frost & Sullivan.

“There is no doubt that the share of thermal technologies is being pulled away by membrane processes, yet a constant evolution of thermal technologies and increased investment in R&D is seen from some of the leading technology companies in the region,” he says. “Industry experts have long predicted that thermal desalination technologies would wither away; however, both MSF and Multi-MED have shown resilience.”

The energy equation

Recent years have witnessed the development of a slew of new desalination concepts aimed at lowering the energy footprint of plants. These include forward osmosis, membrane distillation, tri-hybrid applications using nanofiltration, and low temperature distillation.

Energy can make up to 50% of the cost of producing a unit of desalinated water so improving the energy efficiency of the desalination process has moved high on the agenda of Middle Eastern countries. Governments in the GCC have allocated approximately $100bn towards implementing better water technologies and energy-efficient desalination.

Adding to this is the growing focus on the potential of powering the desalination process with renewable energy. The past year has seen the region take huge strides towards developing renewable power on a large scale. Dubai became the first country in the GCC to announce a major solar power programme with plans to add 3,000MW by 2030.

The tipping point was the drop in the cost of producing solar power from photovoltaic technology in the Middle East to the lowest level in the world. At below $6 cents per KWh, solar power can now compete with power produced by burning hydrocarbons. And that watershed moment looks to have paved the way for the imminent procurement of solar power on a large scale in the GCC’s largest economy, Saudi Arabia.

There are already a number of solar powered desalination pilot projects under development in the Gulf.

The Kingdom of Saudi Arabia, for example, has started work on its first solar powered desalination plant in Al-Khafi near the border with Kuwait. The plant will produce 30,000 m3/day of desalinated water in the first phase and will be extended to 300,000 m3/day capacity in phase two. Plans are to extend the initiative throughout the Kingdom in phase three.

The Environment Agency - Abu Dhabi (EAD) and the Abu Dhabi Water and Electricity Company have awarded contracts to four international companies to develop pilot projects for desalination powered by clean energy. An appropriate technology will be selected to scale up the project at a commercial level.

And just recently Dubai Electricity and Water Authority (DEWA) revealed plans to develop a solar powered desalination pilot project based on reverse osmosis technology.

Despite these encouraging signs, industry experts caution efforts at combining renewable energy and desalination are still at a very early stage.

“Currently, there is some work occurring in the region but it is still at a pilot scale,” says GE Water & Process Technologies’ Van Ert. “It appears more developments are needed to advance this approach and achieve an efficient and cost effective solution. But, as awareness and emphasis is applied to renewable energy, advancements are likely to follow.

”Roland Ang of Hyflux concurs: “Desalination powered by renewable energy would be ideal for the energy-intensive desalination process, but currently the technology hasn’t matured to enable feasibility.”

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