The two PG&E studies show that electrodialysis is the clear energy-efficiency winner for the clarification process. However, the studies also show that makingmodest changes to the cold stabilization process can significantly increase efficiency for this commonly used method.

Since insulation potentially accounts for the majority of cold stabilization energy savings, winemakers are encouraged to insulate tanks. In fact, according to a PG&E Non- Residential New Construction study prepared by Applied Technology Services, simply installing three inches of insulation around tanks can cut energy use by almost 95%. This supports the dramatic drop in electricity — from 1,200 to 22 Wh per gallon — between the two test sites in the Emerging Technologies studies.

In addition to energy savings, electrodialysis offers the benefits of less processing time and reduced wine loss. Although these benefits go beyond the scope

The nuances and long-term plans of each winery will influence the most appropriate method.Winemakers must be especially aware that adopting electrodialysis technology results in increased water consumption that necessitates increased wastewater treatment and associated costs.

Fetzer Vineyards was in a unique position in that they already employed multiple water conservation methods and it was therefore easy to accommodate extra waste water. Winemakers who do not have this capability must be prepared for increased water related expenses. To that end, PG&E will conduct a study in which winery wastewater treatment practices will be examined and benchmarked.

"We are aware that electrodialysis uses more water than traditional stabilization," says Fetzer's Thrupp. "However, the relatively small increase in water for this technology is addressed and compensated for by ongoing water conservation practices throughout the winery, bottling facility, and vineyards. In addition, the water is treated on-site through aeration ponds and is reused in the vineyards and landscaping."

PG&E supports the adoption of electrodialysis technology forwine stabilization as an energy efficiency tool, and encourages winemakers to insulate tanks to save energy in the cold stabilization process. To that end, PG&E is currently offering incentives for adopting non-mobile electrodialysis technology or for insulating wine tanks. To find out how PG&E can evaluate your possible energy savings using electrodialysis technologies, call the PG&E Business Customer Service Center (800/468-4743) and ask for the project manager in your area.

[Steve Fok, PE, has been managing power generation, environmental compliance, and energy efficiency projects at PG&E for 29 years. Steve can be reached at 415/223-4735 or SKF2@pge.com.]