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W i n e s & V i n e s A P R i L 2 0 1 4 55 G R A P E G R O W I N G W I N E M A K I N G eries already do this for safety reasons. However, sequestering or using the CO 2 makes a lot of sense, and the byproducts may even have value. After impurities are removed in gas absorption columns, the carbon diox- ide can be reused for car- bonating beverages, in processing or even feeding algae in ponds to produce biofuels. The CO 2 can also be bubbled through a solu- tion of calcium hydroxide to produce cal- cium carbonate (chalk) used in wallboard or other products. Minimizing water use Water has always been tight in California, and it's becoming more so, a situation highlighted by the current drought. Wine- making typically requires 4 to 6 gallons of water per gallon of wine produced, and most of that is for washing equipment. Some large wineries, however, use little more than 1 gallon of water for each gal- lon of wine produced. Reclaiming and reusing water as well as reducing its use increases sustainability, may lower costs and may also become mandatory. Cleaning in place is one way to do this. Another way to reduce the water required is to capture and use rainwater. Treating and reusing cleaning water is yet another approach. (We're focusing on the winery, but of course recycled water can also be used for irrigation as well as flushing toilets, etc.). To reuse wastewater it must first undergo coarse filtration or centrifugation to remove larger particles, then mem- brane filtration such as reverse osmosis to remove ions and other small impurities. Another "waste" that can be used is heat. Wineries can recycle hot water streams used for bottling line sanitization and tank warming for heating spaces. Likewise, they can recycle cold streams used for tank cooling and cold stabiliza- tion in similar ways. Even better, they can abandon inefficient uses like tank cold stabilization in favor of energy-saving methods like ion exchange. Alternate ways to generate energy are already popular. Photovoltaic cells are commonly used to generate electricity from sunlight, and some wineries also heat water with the sun. These arrays can be placed where they don't occupy valuable vineyard land such as on rooftops, over leach fields and parking lots or even ponds. In the latter case, this also reduces evaporation from the pond. Roof-mounted arrays can reduce heat load on buildings. Photovoltaic cells can also split water and release hydrogen, which can be stored and used to generate electricity in a fuel cell when sunlight is not available or is obscured. Other ways to save energy come to mind, notably configuring buildings to use natural sunlight, daytime heating and night cooling as well as thick insulation to main- tain temperatures. Heat pumps or under- ground arrays of boulders can store excess heat or cold to reduce energy needs. The winery of the future will surely use technology to improve wine, lower pro- duction costs and increase sustainability. Even wineries that turn to traditional approaches like gravity feed, native yeasts and concrete and wood fermentors can benefit from instrumentation and auto- mation that help guide winemakers to making better decisions. Managing temperature gradients in tanks I t's well known that temperature has a big impact on phenolic extraction in red wine fermentations, but enologists are learning more and more about this complex subject through research. Temperature affects both the optimum length of fermentation and color and phenol extraction. However, gradients exist within tanks and the cap. This can cause different extrac- tions of anthocyanins and tannins, for example, to occur at different tank levels and locations. Researchers at UC Davis are measuring these gradients with the aim of avoiding hot spots and guiding the length and timing of pump overs to control phenolic extraction. UC Davis has developed research fermentors that can be programmed for timing, frequency and length of pump overs with ongoing measurements of Brix. It is working on real-time sensors for color, phenolics and cell concentration. At present, temperature control in large fermentation vats is rather basic. One issue is that the cap can be sig- nificantly warmer than the juice below, causing faster extraction in the cap. This temperature difference can be controlled using cap management with pump overs or punch downs. However, the volume of pump over does not seem to affect extraction. Monitoring and controlling these param- eters could improve the process. P.F. These automated tank-temperature monitors are already in use at the UC Davis winery. Dr. David Block notes that automating processes for stainless steel tanks (like these recently installed at UC Davis) has been common in the dairy and pharmaceutical industries for years. UC DAvIs