发表时间：2014-12-12 14:23:03 编辑：管理员 来源：sacbee.com, BY NEIL PALMER 访问量统计：5
It is not a matter of having to choose between seawater desalination and water recycling, water conservation and stormwater reuse or economic instruments – it is wise to consider all of them.
California, like many parts of the globe, faces ongoing drought conditions that threaten its livelihood. Recent rainfall can distract from the fact that drought conditions persist and may continue well into the future.
As climate science points to drier years to come, many across the planet are adjusting their traditional expectations of water supplies. Population and demand are also growing and new supplies will be needed.
This week,water leaders from Australia are meeting our Californian counterpartsin West Sacramento to discuss the lessons from our long drought. I look forward to sharing Australia’s successes and failures so that California can learn from our experience without, hopefully, having to face such severe water restrictions and crop losses as Australia did.
We applied a number of techniques including conservation, water trading, stormwater collection and on-site gray water reuse, but one of our more tangible successes has been a $10 billion seawater desalination program with the construction of six major plants in all five mainland state capitals.
While rain has fallen in the east coast of Australia, Western Australia continues with long-term reduction in rainfall, similar to California. The Perth and Southern Seawater Desalination Plants have supplied clean, secure drinking water to residents since the first plant was completed in 2006. They currently provide around 180,000 acre-feet, or 38.3 billion gallons, per year – 45 percent of the drinking water supply to Perth’s 1.7 million people.
The Perth plant discharges concentrate into Cockburn Sound, a confined body of water. If ever there was likely to be a problem with brine discharge impacting the marine environment, it is here.
The environmental regulator recognized this, and it has been one of the most-monitored desalination plant outfalls in the world. It has been operating at full flow (at about 70 percent of the size of a desalination plant under construction in Carlsbad) for eight years with no environmental harm.
In addition, the Perth plant (like all the big Australian desal plants) has its energy consumption entirely offset by renewable energy. It is thanks to desalinated water that Perth will be able to continue to function sustainably in the long term. Indeed, it is a most livable city with extensive parks and gardens.
In the eastern states, the drought broke in 2010. Critics of desalination with short memories have been vocal. However, the desalination plants will be operating for at least 50 years, during which time there will inevitably be more droughts, growing demand and, possibly, a drier and hotter climate. Taking a long-term perspective, most people are reassured by the knowledge that they will always have water security, whatever the weather. The cost per household for this insurance against future water restrictions is relatively modest.
California has some of the most fertile agricultural land on the planet, and it serves as an economic boon for the state. The provision of affordable alternative sources of urban water such as desalination ensures that inland regions and agriculture can have a more secure supply.
Coming from Australia, it is a privilege to visit California, which is renowned as the birthplace of reverse osmosis desalination technology in the 1950s and 1960s. It is surprising to me that there are not many more desalination plants in California.
One of the important lessons we learned in Australia is the importance of developing a portfolio of water sources, with some of them being independent of weather and climate. So it is not a matter of having to choose between seawater desalination and water recycling, water conservation and stormwater reuse or economic instruments – it is wise to consider all of them.
California should realize that investing now in secure sources of water like seawater desalination can enable rapid and affordable solutions without adverse environmental impact. Such supplies are always available in times of drought and scarcity and will ensure that generations of coastal-dwelling Californians will enjoy a lifestyle that can rely on a secure water supply.
Neil Palmer is CEO of Australia’s National Centre of Excellence in Desalination.