Winery Water and Energy Use, and New Technologies.
Reproduced with permission from the Enology-Grape Chemistry Group at Virginia Tech
A study conducted in California several years ago reported that the wine industry was the largest energy user among food industries (Selfridge, 2009). This realization, coupled with economics and concerns regarding climate change, has promoted continued concern about energy and water use.
The word sustainable became common vernacular in the wine industry by about 2008. Not fully defined, it meant different things to different people, which was likely part of its appeal. It added a virtuous green dimension which often represented some nebulous combination of ecology and the environment. For some, it was a new way of packaging an old idea – corporate social responsibility. For those in the wine industry, it usually meant some professed emphasis on energy, water, chemical, and/or packaging management.
By 2009, sustainability began to take on a new ethos that also placed emphasis on economics. To sustain profits, virtually all in our industry continued to attempt to cut costs. However, the forces that initially motivated the wine industry to be concerned about environmental and ecological practices have not changed and will not disappear.
Today, the term sustainability has been perhaps overplayed. However, it is essential that industry members understand the difference between conservation, and energy and water efficiency. They are not the same. We have placed a great deal of emphasis on conservation, but much less on improving efficiency.
Sources of energy consumption in the winery, according to A Guide to Energy EfficiencyInnovation in Australian Wineries, are as follows. It has been suggested that it takes 10 liters of water to produce one liter of wine, 2.4 liters of that in the winery alone, and about 0.71 GJ of electricity to make a kiloliter of wine (McCorkle 2009).
- Refrigeration: 40-60%
- Pumps, fans, drives: 10-35%
- Lighting: 8-20%
- Compressed air: 3-10%
- Packaging and bottling: 8-30%
- Other consumptions: 3-15%
a. Winery Design and Energy and Water Use. We can divide energy and water use into building design features and winery operational components. Energy/water use and winery design considerations include the following:
- LEED certification
- Building materials
- Earth-sheltered buildings
- Green roofs
- Building orientation/insulation
- Brise soleil/solar blocks
- Natural lighting and venting
- Rainwater collection
- Alternative energy, including geothermal, solar, wind
Energy and water use is not formulaic. Environmental and ecological practices are site- and operationally specific. Each producer should answer some fundamental questions, including these: What is your philosophical disposition with regard to ecology and the environment? What is the true measure of your impact, your footprint, at your location? What are your goals? A list of goals were reviewed by the Monterrey County Vinegrowers Association, and includes the following: saving money, staying ahead of regulations, recognition, renewed energy, possible carbon credits in the future, and net zero energy use.
There are, of course, levels or tiers of ecological and building practices. LEED certification, for example, has a range of 25-69 attainable points. The number of points determines the level of certification, from Basic, to Silver, Gold, and Platinum. The following are some winery building considerations adapted, in part, from one of our Winery Planning and Design seminars, presented by Joe Chauncey (2008) of Boxwood Architecture, Seattle, Washington:
Use regional materials and local fabricators:
- This helps to reduce transportation impacts and stimulates the local economy.
Use building and construction materials with a high percentage of recycled content:
- Straw-construction buildings are becoming more popular. Straw is the inedible stalk of grains such as wheat, rice and rye.
Create a building with mass:
- A thin-wall building with a metal skin and batt insulation allows heat (and cold) to penetrate more quickly than a thick-wall building.
- Build with concrete, masonry, or stone, and sandwiched insulation.
- Thick-wall buildings absorb heat all day long, and release it at night with little impact on the interior temperature.
Use cool-build materials:
- If metal roofs are utilized, use materials developed or painted with infrared-reflecting pigments to lower the amount of heat-absorbing light. This can create a cool roof.
- Cool roofs reduce heat absorption and cooling costs.
Reduce heat loss or gain:
- Have portions of buildings underground or partially underground to take advantage of the earth’s constant temperature.
- Have barrel storage areas where walls are in contact with the earth, which can eliminate the need for cooling. Air movement, from fan coil units cooling an above-ground barrel room, dries out the barrels and increases evaporation. To help control this problem, winemakers humidify this space, adding cost and some additional potential problems.
- Barrel rooms that do not need cooling will promote less evaporation.
Consider geothermal heating and cooling:
- Water circulates in a sealed loop that extends well into the earth.
- In the winter, the water absorbs heat from the earth and carries it to a compressor which raises the temperature.
- In the summer, the water takes heat away from the building and transfers it to the earth.
Orient buildings to take advantage of solar energy or maximize shading.
Optimize the use of shading:
- Blocking sunlight that would fall on building surfaces can dramatically reduce cooling loads.
- Plant trees along the south and west faces of buildings.
- Install wall trellises; grow vines or shrubs to shade walls.
- Design sunscreens that shade and ventilate heat away from wall surfaces.
Consider low emissivity insulation on windows:
- Metal oxide glazing can allow the sun’s heat and light to pass through glass while blocking the heat from leaving the building, thus reducing heat loss.
Increase daylight levels and outside views:
- Add skylights or upper windows (clerestories), while avoiding direct sunlight on barrels or tanks.
- Design additional windows and skylights in subterranean spaces to expand views to the outdoors from as many occupied spaces as possible.
Use minimal exterior lighting and computerized cut-off fixtures, motion sensors, and/or timers for both interior and exterior lighting:
- Use environmentally-sound lighting.
- Paint inside walls and ceilings a light color, as dark colors absorb light.
- Fluorescent lights produce the same amount of light, yet generate one-fifth as much greenhouse gas.
Design natural ventilation:
- Design windows or louvers at or near the floor level of the winery to bring in cool night air that blankets the ground. By also opening a louver in the upper part of the winery, a passive ventilation system is created. Hot air that has been accumulated during the day can be exhausted through a louver in the clerestory area. The hot air leaving the winery pulls cool night air in the lower louver. Such purging can be done without mechanical equipment.
b. Monitoring Winery Energy Use. Energy and water use are tied together. The Wine Institute and California Association of Winegrape Growers have divided winery energy use among the following:
- Refrigeration system
- Tanks and lines
- Motors, drives and pumps
- Heating, ventilation and air conditioning (HVAC)
- Lighting—offices and labs
- Lighting—outdoor and security
- Office equipment
- Winemaking processes
Each producer interested in energy and water efficiency should quantify or benchmark their activities. The advantages of benchmarking lie in our ability to measure, contrast, and chart our true progress. Monitoring winery practices involves identifying resource use and designing practices to lower use (Boulton, 2008, 2009b). A number of matrices can be reviewed, including those suggested by Michael et al. (2009):
- Wine volume/ton
- Total energy/ton
- Water/volume of wine produced
- Personnel hours/ton
- Wastewater COD and BOD/ton
Wineries need to properly compare and contrast their facilities and performance against others, and understand the importance of scaling. For example, energy and water use should be evaluated within a relative production volume or scale, in order to compare and contrast different size wineries.
Scaling is not linear. For example, large wineries generally have a smaller surface area per wine volume produced than small wineries (Boulton, 2009a). This is relevant in benchmarking and comparing the energy and water use within our industry. Carbon dioxide emissions, on the other hand, can be compared directly, based on tonnage or fermentation volume. In the absence of energy and water scaling, our industry will not be able to accurately establish benchmarks or evaluate progress in environmental and ecological sustainability.
If you don’t know where you are going, any road will take you there.
c. Winery Processes and Energy and Water Use. Winery energy-intensive practices include the following (Boulton, 1998):
- Cooling of white juice for settling
- Cooling of wine for bitartrate stabilization
- Poor tank insulation
- Multiple tank transfers
As suggested, in part, by Boulton (2008), energy saving practices to consider are numerous and include the following:
- Flotation settling for white juice
- Fluidized bed for cold stabilization
- Electrical conductivity for cold stabilization
- Use of inhibitor agents for cold stabilization
- CIP (clean in place), pigging systems
- Protein adsorption columns for the elimination of the need for bentonite
Because refrigeration accounts for 40-60% of the total energy utilization of a winery, evaluation of this area is a logical point of focus.
d. Flotation for White Juice Settling. In conventional white wine processing, refrigeration is often used to settle juice. Flotation is a solid-liquid separation procedure that uses compressed air or nitrogen gas to saturate grape juice or must in a tank. Gas bubbles adhere to particulates in the juice, enabling them to float to the top where a foam cap forms. The cap can then be separated from the clarified juice. Fining agents, such as bentonite, gelatin, silica or carbon, may be added prior to gas saturation to optimize particulate flocculation, if needed.
Flotation is generally used to clarify white and rosé juice, but can be used to clarify red juice that is being put through thermo-processing such as flash détente. There are several advantages to using flotation settling, as suggested by Lansing (2012):
- Reduces clarification time, space and energy.
- Can be done quickly, in several hours.
- Reduces number of settling tanks, therefore space and cleaning.
- Because this is done relatively quickly, there may be a benefit with regard to preserving aromatic quality. Some varieties benefit from hyper-oxidation and, therefore, air vs. nitrogen gas can be used.
- Can result in juice with lower NTU compared to conventional cold settling.
- Can recover gas used in this process, if desired.
e. Cold Stabilization Procedures and Energy Use. Several factors can influence bitartrate stabilization, as discussed by Zoecklein et al. (1999), including the following:
- Nucleation, or the number of nuclei on which crystals can form and grow
- Diffusion, or the rate at which the dissolved potassium bitartrate comes into contact with the crystal formations
- Crystal growth rate
There are several methods commonly used to stabilize bitartrate, including refrigeration, refrigeration with contact seeding, fluid bed technology, electrical dialysis, and crystal inhibitor compounds.
i. Contact seeding. In this process, chilled wine is commonly seeded with powdered potassium bitartrate of a certain size, which hastens the crystallization rate by lowering the activation energy required for crystal formation (see Zoecklein et al. (1999) and online publication titled “A Review of Potassium Bitartrate Stability” at www.vtwines.info).
ii. Fluid bed technology. In this process, a wine is filtered through a potassium bitartrate bed where crystallization may occur. Wine can be passed through the crystal bed several times until stabilization is reached.
iii. Electrodialysis. In an electrodialysis system, tartaric acid is removed as wine passes through an electrical field which separates ions using anionic and cationic membranes. The ions are potassium (K+), calcium (Ca++), and negatively-charged tartaric acids.
The cationic membrane allows positively-charged calcium and potassium to pass through, while the anionic membrane allows negatively-charged tartaric acid ions to be removed. As depicted below, one chamber holds wine, while another contains a solution of potassium and calcium ions. Water flows through the second chamber, creating a brine solution made up of the potassium and calcium ions, as illustrated by Wollan (2010) (Figure 1).
There are several advantages in the use of electrodialysis, including the following (Wollan, 2010):
- More energy efficient than conventional stabilization. For example, compared to conventional cold stabilization, a reduction from 1200 watt-hours/g to 7.9 watt-hours/g (Fok, 2009).
- Reduction in processing time by as much as 97%.
- Components are not changed as compared with conventional cold stabilization or contact seeding. Thus, there is little impact on titratable acidity (tartaric and malic acids) and, therefore, pH.
- Potassium bitartrate and calcium tartrate salts are removed from solution.
- Portable systems will soon be available
The major disadvantage is that this process uses a significant quantity of water.
iv. Addition compounds, including CMC. Additional compounds, such as carboxymethyl cellulose (CMC) may be alternatives to contact seeding, electrodialysis, and other wine additives, including mannoproteins and metatartaric acid, at least for some wines (Zoecklein et al., 1999).
CMC is produced by reacting cellulose and choroacetic acid under alkaline conditions. CMCs function in wine in a similar manner to mannoproteins by physically inhibiting nucleation and crystal growth, by acting on the face of a growing crystal and restricting further growth.
There are a number of different CMCs on the market; the variables include the polymer length and side-group substitution. The length governs viscosity, while the number of glucose side groups impacts solubility, which impacts effectiveness.
Some advantages to the use of CMC may include the following (Bowyer et al., 2010):
- Unlike conventional cold stabilization, addition products such as CMC do not result in modification of pH, TA or other sensory characteristics
- Lower energy costs due to the elimination of refrigeration
- Suitable for relatively-unstable wines in contrast to mannoproteins
Some disadvantages to the use of CMC include the following:
- It is not a natural product
- Wines must be bottle ready; no subsequent physiochemical modifications can occur, including blending, acid addition, de-acidification, etc.
- Not recommended for reds and some rosés
- CMCs interact with proteins; wines must be protein stable and not contain lysozyme
- Can have dramatic effect on filterability; it is recommended not to filter wine within 24-48 hours post-addition
f. Simple, Practical, Winery Energy Conservation Steps. The reasons for energy efficiency are numerous, and include monetary savings, lower environmental impact, enhanced equipment longevity, optimizations of winery systems, and marketing and promotional benefits. The following suggestions are adapted from the WIES Program (Wine Industry Efficiency Solutions), presented at the California Sustainable Winegrowing Alliance meeting in 2010:
- Wine tank insulation
- Glycol pump VFDs
- Glycol and hot water pipe insulation
- Strip curtains for walk-in boxes
- Replacement of HID or incandescent fixtures with fluorescent fixtures
- Replacement of T12 fixtures with T5 or T8
- Occupancy sensors
- Efficient evaporator fan motors
- Steam or water process boilers
- Variable frequency drives on pump motors and condenser fans
- Evaporator fan controls
- Floating head and suction pressure controls
- Energy-efficient motors
- Air-cooled to evaporatively-cooled condenser upgrades
- Wastewater pond aerator upgrades
- Dissolved oxygen sensors for wastewater ponds
- Air compressor upgrades and replacements
- Glycol tank insulation
- Heat recovery – barrel washing and refrigeration
g. Winery Operations and Water Use. The average water use per unit production in the winery is about 2.0kL/ton crushed, with a best practice water use of about 0.4kL/ton. This is equivalent to an average water use of 2.0L per 750mL bottle of wine. Bottling onsite significantly increases average water levels used, from 1.4L per bottle for wineries that do not bottle onsite, to 2.5L per bottle for wineries that do bottle onsite. Several studies have noted the following:
- Water usage in small wineries is extremely variable.
- Bottling is responsible for about 40% of wastewater for wineries surveyed.
Throughout the winery, water is the most important and widely-used cleaner. According to the Wine Institute, the major areas of use include the following:
- Crush operations
- Press operations
- Fermentation tanks
- Barrel washing and soaking
- Cellar operations
According to Boulton (2009a), the major water-intensive practices include tank cleaning, barrel cleaning, and tank transfers. Therefore, reducing winery water use includes this:
- Minimum tank transfers, no more than 4
- Adapt clean in place (CIP) tank and barrel washing
- Eliminate bentonite and diatomaceous earth
- Capture, filter, and re-use cleaning solutions
- Adopt potassium-based cleaning salts
CIP (clean in place) and the use of protein adsorption columns can significantly reduce water use, energy load, and lees loss. Simple steps, such as the addition of tannin pre-fermentation, can help precipitate proteins and aid in lowering the subsequent bentonite requirement.
Cleaning chemicals. Chemical additives for cleaning and sanitization are a primary source of “problem” ions such as sodium in winery wastewater, apart from product (wine) losses. The concentration of these ions has potential implications for wastewater re-use, particularly regarding the sustainability of irrigation practices using wastewater with elevated salinity concentrations. Alternatives to caustics (sodium hydroxide) have been introduced to improve the quality of wastewater. These include the use of hydrogen peroxide, rather than ozone or chlorine dioxide. The use of potassium hydroxide (pH 11.5) and potassium bisulfate (pH 2.5) with hydrogen peroxide is now a common replacement for sodium salts.
A first step towards water conservation is an evaluation of consumption. Wineries should equip processing areas with water meters to track usage, detect leaks, and show where improvements can be made. Fitting equipment with automatic shut-off devices, and installing water-efficient nozzles, heads, and faucets can be an asset. Additionally, water efficiencies can be achieved by capturing rainwater, segregating storm water, and recycling water.