Vines and Wines:
Winemaking’s environmental effects in California By: Andrew Baumgartner
California is a large and diverse state, ranging from the saline lake of the Salton Sea in the far south to the towering trees of Redwood National Forest in the north, from the inland farms in the east to the coastal beaches in the west. Scattered throughout the state are areas suitable for viticulture: the growing of wine grapes for the production of wines. California’s wine industry is so large, in fact, that the state hosts 90% of the total grape growing acreage in the United States. A recent study, published in the International Journal of Life Cycle Assessment, has revealed some of the surprising effects that various wine production methods have on the environment. Because of the size of the California wine industry, the study focused on the state’s vineyards specifically. Wine is a popular alcoholic beverage worldwide, and California wines have become highly regarded since the first vineyards were planted in the early 1700s. Napa Valley and Lodi, a viticultural area within the nearby Central Valley were the two main regions observed throughout the project. By examining the energy used and the global warming potential per metric ton in 240 production scenarios through observation of 90 different vineyards, the researchers were able to calculate which approaches were the most sustainable and environmentally friendly.
California’s viticultural areas, shaded, with regions of production flagged. The study’s two areas of focus are circled in red.
The Napa Region Napa Valley is an area of California synonymous with wine production. Chances are that if you have heard anything about California wine, you think of Napa first. Napa, therefore, has the highest prices for wine grapes in the state, between $2269 and $4348 per metric ton. On a per bottle basis, this makes Napa wines $6 more, even for the same grape variety, on average. The overall average cost of a Napa wine bottle is $29.60. The harvesting methods used in Napa to collect the grapes are more traditional, using human harvesting teams to handpick the grapes from the vines. During grape growth in the modern day, however, some technology is used, such as diesel-powered wind machines to prevent frost. Mobile light towers allow for nighttime grape collection by the harvesting teams. Tractors transport the full collection bins out of the fields, where forklifts load the bins up onto waiting semi-trailers which transport the collected grapes to the winery.
A traditional hand harvest in Napa
Night harvesting in Napa
The Lodi Region Lodi, a region in the large, sweeping Central Valley, is not as widely known for wine production. The area is an extensive agricultural production zone for a wide variety of crops, rather than simply an area focused on wine production. Lodi grapes are not as highly valued as those in Napa, fetching between $538 and $1024 per metric ton. Lodi’s highest grape value, therefore, is still four times less than Napa’s highest grape value. The overall per bottle average cost of a Lodi region wine is $12.80.
A mechanical harvester used in Lodi
The methods of cultivation and harvest in Lodi vineyards utilize more modern tools than those used Napa. Most notably, a machine harvester collects the grapes from the vines rather than teams of human workers. The harvester operates by shaking the grapes off the vines and into collection gondolas. Tractors pull the full gondolas out to waiting semi-trucks, which have special trailers for the gondolas. A grape collection gondola
Methods Compared The traditional methods of grape growing versus the more modern methods do produce different figures. The Napa models contained 2,202 vines per hectare, which would produce an average of 9.4 metric tons of grapes per hectare through hand harvesting. The study observed that the use of human workers to hand harvest took 4.9 hours per hectare. The wind machines used in Napa required approximately 4,320 mega-joules per hectare each year in diesel energy. Lodi models contained 1,538 vines per hectare, but the machine harvesting method produced 17.8 metric tons of grapes. With one machine harvester, the work took only 1.2 hours per hectare, and since there was no frost protection, there was no diesel energy expended in that manner.
Survey Says... The 240 different computer generated scenarios tested in the study produced a wide array of results. However, 12 different scenarios were selected for a more detailed comparison, as they represented plausible and reasonable management scenarios for the regions and their systems of management. All scenarios were analyzed by two different measurements: on a per metric ton basis and a per hectare basis. In the evaluation of the 12 detailed comparison scenarios, researchers found that Napa wine grapes were twice as intensive in global warming potential (GWP), used double the amount of energy, and used more water as well. In the two most likely scenarios of these 12, Napa production methods spent 6,529 mega-joules per ton, produced 456 kilograms of carbon dioxide emissions per ton, and used 265 cubic meters of water per ton. By comparison, Lodi production methods expended 2,759 mega-joules per ton, created 203 kilograms of carbon dioxide emissions per ton, and consumed 141 cubic meters of water per ton. (See fig.1).
fig.1: The chart above shows the results of energy use, GWP, and water usage in the likely management scenarios of Napa (N) and Lodi (L). The scenarios show more results for Lodi because of the more varied modern methods used in the region.
When looking at the data on a per hectare basis, however, Napa’s figures only show an approximate 16% higher rate of emissions and resource usage than those of Lodi.
Why the Difference? There are several reasons why the results are so different. First of all, when examined on a per hectare basis, the hand harvesting and frost protection methods in Napa contribute to these higher figures. Because Napa also decreases the number of grapes on the vine throughout the growth cycle, lower overall yields become the main reason for the more significant difference when examined on a per metric ton basis. The benefit of hand-picking is the main reason for Napa’s higher grape values per metric ton, as wine grape crops are often intentionally decreased to control the aroma and flavor attributes.
Profit vs. Environment, or Goliath vs. Goliath The results of the study place Napa Valley in a unique situation. By intentionally decreasing the overall yield of the crop, the value of the grapes increases. Napa vineyards can continue to be managed for these lower yields because of these higher prices, but the practice is not as environmentally friendly. The energy requirements for using human harvesters versus machine harvesters is significantly higher in the case of the former versus the latter. Mechanical harvesters, though the average consumer might consider to be more environmentally damaging, ultimately have a lower impact than human workers primarily because of the efficiency of the machine. The ability to complete the same job in a quarter of the time becomes a significant advantage. Therefore, the modern harvesting and growth methods used in the Lodi region are more environmentally sustaining than those traditional methods used in the Napa region.
Pitfalls and Solutions The study is the first to look into the comparative effects of wine grape cultivation on the environment. Despite the results, the team behind the project admits that improving grape yields is not necessarily an option for vineyards focused on wine grape flavor and aroma, or even those with the competing goal of maintaining a higher price point. This leaves out the traditional efficiency improvements that would normally be suggested. Instead, the study promotes the options of altering cultivation practices, or developing high-value co-products to offset the environmental costs, such as extracting the antioxidants contained in wine grape byproducts.
Future Considerations With a large and varied system, the viticultural industry in California can benefit from considerations such as the development of high-value co-products, which could not only make them more environmentally conscious, but also increase profit. Most importantly, considering that 90% of all grape cultivation occurs in California, the state’s vineyards and wineries should consider the most appropriate ways to become more environmentally sustainable. If California begins to one day require vineyards to account for their carbonemissions, the increased taxes might put Napa growers and other vineyards at risk of going out of business. Therefore, looking into potential new methods is not only important, but may soon be vitally necessary to survive.