Modern Alchemy: Wind To Water

The Perth SWRO plant in Western Australia utilizes a combination of clean wind power and the highest efficiency ERD available for one of the most efficient and environmentally friendly desalination plants in world.

A Thirsty Natio

The ongoing population growth in Australia’s coastal communities combined with the worst drought in a century have unhappily converged creating the necessity for the Australian government to find water sources that are both located near to the large coastal communities that need them and that aren’t subject to the whim’s of changing weather patterns.

The Solutio

Facing impending water shortages, in April 2005, Western Australia's (WA) Water Corporation made a decision to form a public-private partnership with global water treatment company Degrémont. Degrémont has a 25-year operation agreement with the government owned Water Corporation. The first train (of 12 trains) of the Perth Seawater Desalination Plant (PSDP) is on target to start producing fresh water in November 2006.

The144,000 m3/d Perth SWRO plant, located at Kwinana, will be the largest SWRO plant in the Southern and Eastern hemispheres and is expected to augment the water supply for Perth by more than 17%.

A Novel Plant Design that’s Earth Friendly

As part of Water Corporation and WA’s very progressive stand of not producing additional greenhouse gases, electricity for the plant will be generated by a novel 80 MW wind farm located in WA’s Midwest region. The wind farm, already commissioned, is expected to contribute 270 GWh/year into the general electrical grid, offsetting the Perth SWRO Plant estimated electrical requirement of 180 GWh/year. Once in operation the Perth SWRO plant will have the distinction of being the worlds largest “green-powered” desalination plant.

The plant, with 12 SWRO trains with a capacity of 160,000 m3/day and six BWRO trains delivering a final product of 144,000 m3/day, will have one of the world’s lowest specific energy consumptions, due in part to the use of Energy Recovery, Inc.’s (ERI's) PX Pressure Exchanger”š energy recovery devices (ERDs). The ERI PX is an isobaric chamber type of ERD which recovers energy in the brine stream and delivers it to water going to the membrane feed at a net transfer efficiency of up to 98%, which makes it the world’s most efficient ERD commercially available.

The Perth plant will also have one of the most comprehensive environmental monitoring programs in the world, continuously monitoring the seawater intake and brine outfall as a condition of its continued operation.

The combination of unheralded environmental protection and monitoring, low specific energy consumption, and the use of a renewable energy make the PSDP a world model for providing water in an environmentally sound and sustainable manner, almost magically converting wind to fresh water.

Cost-Effective Design and Solution

At A$323 million (387 million including integration assets) for the 144,000 m3/day Perth plant it is also one of the most cost effective projects of its size (compare to an estimated A$869 million (1.153 billion with integration assets) for the planned 125,000 m3/day Australian Gold Coast SWRO project). The Water Corporation has demonstrated that by using a well planned alliance approach with a desalination plant can be environmentally responsible, well designed, and very cost effective all at once.

ERI PX Details

The Water Corporation and Degremont team selected ERI’s PX technology for their optimized design because they offer significant benefits to SWRO plant designers and operators including the highest available net energy transfer efficiency and the lowest lifecycle costs. Additional benefits include maximum design flexibility, reduced high-pressure pump costs and operational flexibility.

Among the commercially available isobaric ERDs, the PX Pressure Exchanger isobaric ERD also provides the following added advantages:

• Highest available Net Transfer Efficiency ”“ up to 98%
• No bearings, seals, valves - maintenance free operation
• Total design flexibility ”“ for changing conditions
• No wetted metal parts that are subject to corrosion
• No required complicated computer controls
• No vibration, lateral loads, or pulsation
• No potential metal fatigue issues
• Dependability and long life design
• Installed redundancy for maximum on-line time
• Only 80 kg per each PX-220, no special skid or foundation requirements
• Housed in standard SWRO pressure vessels, no special tools required
• Smallest footprint by a factor of 6-10 times
• Local support and service in Europe, Australia, Asia, Pacific, Middle East and North Africa, and the Americas.

Today, PX technology has emerged as the industry standard solution for seawater desalination, with over 5,400 PX’s installed in plants worldwide, significantly reducing the cost to produce over 4.5 million m3/day of fresh water, and saving customers an estimated 502 MW of energy or $264 million a year in operating costs, and reducing CO2 emissions by nearly 4 million tons over a 20 year life of a plant the size of Perth.