Water issues have always been an integral part of California history. Rapid growth led to rapid increase in water demand, and many rivers and lakes were modified or created to quench the thirst of the millions settling out West. Advances in technology and increasing environmental awareness in the government and corporate sectors led PG&E and the US Green Building Council to establish an annual Water Conservation Showcase, now in its seventh year. The Alliance attended the March 23rd event, which consisted of keynotes, panels, and a detailed technology exhibition.
One of the more impressive case studies profiled at the exhibition is San Jose’s water recycling facility, built in 1997. The city of San Jose has the largest water recycling facility in the US, reusing 10,000 acre-feet (AF) per year (an acre-foot is the volume of an acre of water one foot deep, or approximately 326,000 US gallons). Sim Ong, the presenter and representative from San Jose, noted that out of the city’s 80 large water-chilled cooling towers for building air conditioning, 40 chillers (making up about 1,700 AF/year of potable water consumption) are located close enough to the recycled water pipeline to replace potable with recycled water. By using recycled water in the chiller towers, San Jose’s customers experience multiple benefits including lower cost, consistent quality, reliability of supply, and up to four LEED points. Improved reliability stems from the fact that recycled water supply is directly related to urban water consumption, which is fairly regular, whereas traditional water supplies fluctuate widely with weather and seasonal water conditions. Society also benefits by decreasing the amount of potable (potentially drinkable) water used and reducing wastewater runoff into San Francisco Bay.
Using recycled water in chiller towers does have some challenges keeping it from wide acceptance, and many of those involve additional commitment of resources. Customers have to adjust their treatment methods, modify plumbing configurations, acquire permits, train supervisors and staff, and accept and invest in the new technology, trusting that this investment will be outweighed by the benefits that recycled water provides. There are some technical challenges as well, as the recycled water will have to be treated like any make-up water to prevent scaling, corrosion and biologic buildup. New electrostatic and electromagnetic technologies remove scale without the use of chemicals and help further reduce water consumption.
While using recycled water in chiller towers is an emerging technology with few documented case studies, it nevertheless has the potential to save significant amounts of water and energy, and we look forward to hearing more about it in the future. For more information on recycled water, see the Alliance’s 2008 study, The Role of Recycled Water in Energy Efficiency and Greenhouse Gas Reduction.
With a strong focus on emerging technologies such as recycled water, many of the case studies presented seemed to take for granted that saving water was a good idea; only a handful of case studies provided an economic argument for conservation. Most of the arguments focused on water scarcity and security issues, and while those issues are certainly very important, it’s hard to make a case to a building manager or property owner when the economics don’t work out.
This is a bit concerning because, as author David Carle suggested in his keynote presentation, conservation is the most practical option to meet the increasing needs of the state of California. Building more dams and waterways is expensive and environmentally damaging, and is only a temporary solution to the problem: Southern California is already populated by 18 million people with local resources only able to provide water for 3 million. Providing an alternate source for potable water through desalination is very expensive and also environmentally damaging (e.g. pumping waste brine back into the ocean).
It seems that the current price of water does not reflect the state of emergency many in the water business perceive. Panelist Bill Wilson, of Environmental Engineering and Sustainability, put it aptly: the cost of water is cheap; but the cost of no water is very expensive. Reusing water, like watering non-food crops with treated waste effluent, seems to provide both economic and conservation benefits. But until the price of water increases to accurately reflect its scarcity, the burden is going to fall on government and regulators to build conservation efforts. Such efforts will require a combination of tighter restrictions on water use (such as the controversial proposal to ban grass lawns in Southern California) and greater incentives for water conservation, both in urban and agricultural settings.
Presentations and more information are available online at the USGBC Northern California Chapter website – take a look and tell us what you think!
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