Wastewater as Energy Source in California

by Medindia Content Team on  April 8, 2008 at 2:30 PM Environmental Health
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Wastewater as Energy Source in California
A pilot program that would use highly treated water to heat and cool buildings is being tried out in Sonoma County, California. Eventually the water could irrigate landscaping and vineyards.

Under the wastewater recycling plan, 55- to 60-degree water would be pumped from the Airport-Larkfield-Wikiup Sanitation Zone Treatment Plant to the business park through underground pipes into a pump inside each building. Once in the pump, a refrigeration device transfers heat to or from the wastewater. A compressor converts that heat energy into warm or cold air that can be pushed through about 3 million square feet of office space at the business park, replacing the traditional heating and air conditioning systems, said Tim Anderson, manager of public affairs for the agency.

In this "open" system, the water could also be used to irrigate landscaping, or, with a secondary set of pipes, flush toilets. Otherwise, the chilly or hot water - between about 40 degrees and 150 degrees - would pass through underground pipes to two adjacent reservoirs. The arrangement could work particularly well for small or midsize cities or suburbs where the energy needed to pump water to low-slung buildings is much less than for skyscrapers.

If the ambitious, expensive plan gets off the ground, environmental planners in similar-size cities around the country theoretically could use the template - developed in part by scientists at the Los Alamos National Laboratory - to slash power bills and better use every last drop of water.

"Recycled water is a new energy source," said Grant Davis, assistant general manager of the Sonoma County Water Agency. "Water and wastewater that you'd normally have to treat and dispose of will become the source for heating and cooling."

The project has gained steam in the past few months as Pacific Gas and Electric Co. and some of the biggest names in the wine business have signed on; in March, county supervisors approved $1 million for a feasibility study.

The flurry of interest comes as more cities and businesses take a hard look at their contributions to greenhouse gas emissions and climate change, and national labs expand their research to include not just military security, but water, energy and economic security, says Kelly Zito writing in San Francisco Chronicle.

"Carbon-free" water by 2015 is the stated goal, that is, using renewable energy sources such as solar and geothermal to power the county's entire network of treatment plants and pumps.

This week, Sonoma officials will meet with lawmakers in Washington about allocating money for this project and establishing a fund, similar to the Community Development Block Grant Program, to pay for similar projects all over the United States. In addition to federal money, Sonoma is considering revenue bonds and creating a special assessment district.

Officials insist the investment is well worth the outlay. For one, they estimate savings of 90 percent on natural gas and about 50 percent on electricity for heating and cooling. The environmental benefits are hard to quantify - but the county is working on it.

Sonoma County Supervisor Paul Kelley was skeptical about the ability of local government to handle sweeping problems such as climate change and greenhouse gas emissions. But after attending the U.N. Climate Change Conference in Bali last year, Kelley changed his mind.

"I know it's costly and challenging and there are a lot of hurdles, but you can sit around and wring your hands over it and do nothing, or you can ... put your shoulder to the wheel and see if we can make it happen locally," Kelley said.

Eventually, planners would like to incorporate vineyards into the loop. Jackson Family Wines, which already uses processed water from rinsing barrels and tanks to irrigate its fields, is exploring ways to store its wine at low temperatures.

"We're looking at every alternative energy source we can if it saves resources and is economically viable," said Clay Gregory, president of Jackson Family Wines.

Vineyards that now draw water only from local streams and wells could stand to benefit even more.

"You see more and more of a need to have additional water sources," said Tom Gore, who oversees farming of 800 acres of grapes for Icon Estates. "The problem is, I don't have a big pipe running through my ranch to allow that right now. In the future, I hope something like that would be available all over the county."

Some top minds are looking into it. At the New Mexico lab, scientists are building a virtual Sonoma County where they can track different scenarios for rainfall, telecommunications infrastructure, commute patterns, demographics and emergency services - a kind of online crystal ball, if you will.

"We all know California will have severe droughts in the next 20 to 40 years and that will affect water supply," said Gary Geernaert, director of the Institute of Geophysics and Planetary Physics at Los Alamos National Lab. "This will help us make educated guesses about what the pressures will be on the public and private infrastructure and help build that into the design."


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