3.1. Baseline Results by Finger Lakes Case Study
The life cycle GHG emissions of each process in the cradle-to-gate production of a bottle of wine and the total carbon footprint result were calculated for each of the three Finger Lakes wineries.
For the Small winery, the life cycle GHG emissions of an average bottle of wine were 1.03 kg CO2eq
. The highest impacts were associated with cultivation, which provides 46% of the total life cycle GHG emissions, and with bottling, which provides 45% of the total life cycle GHG emissions (Figure 3
). The impacts associated with the cultivation process are due almost entirely (97%) to the high mass of Timothy hay applied per hectare over the course of a growing season.
The bottling process includes the transportation of the wine to the bottling facility and the production of the glass bottles. This does not include the impact of the electricity used for bottling, as the impact from electricity use was calculated separately for the entire winery instead of separated by process. The Small winery is the only one of the three case study wineries that bottles off-site, and therefore the impacts of bottling included the transportation of the bottle from the bottling manufacturer as well as the transportation of the wine to the bottling facility. Despite this additional transportation impact, the impacts associated with the production of the glass bottle represents over 99.5% of the GHG emissions contributed by the bottling process.
The third highest impact for the Small winery stemmed from the production of electricity generated for winery operation, accounting for 5.45% of the total. This impact represents a smaller proportion of the life cycle impact than that of the Medium winery, mainly owing to a lower amount of electricity required for the production of each bottle of wine at the Small winery and due to differences in impacts from other processes. The absolute impacts of electricity generation per bottle are nearly equal between the two wineries, differing by less than 0.006 kg CO2eq bottle−1, and are slightly higher for the Small winery.
The processes of cooling, blending, and fermentation are the next highest impacting parameters, imparting an aggregate 3.10% of the total life cycle impacts. However, considering that only the electricity usage for the winery as a whole was modeled, the impacts for these processes were based entirely on the impacts of their inputs. Thus, in spite of this aggregate impact, these processes realistically cannot be considered negligible in terms of influence on the total environmental impact. All other processes together amount to 0.004% of the total GHG emissions.
The baseline life cycle GHG emissions of a 0.75 L bottle of wine from the Medium winery was 0.742 kg CO2eq
. The highest impact among the processes was associated with the bottling process, which includes the production and transportation of the glass bottle (Figure 4
). Bottling contributes 79.3% of the total life cycle GHG emissions for wines produced by the Medium winery. As the bottles are transported between 337 and 4200 km to the winery, in addition to being the heaviest bottles of the three case study wineries (at 0.500 kg), it is reasonable that the Medium winery had the highest climate change impact for bottling between the three wineries (0.589 kg CO2eq
). However, it should also be noted that the transportation of the bottles represents only 12.1% of the impact of the bottling phase; the other 87.9% can be attributed to the production of the glass bottles.
The second highest impact stemmed from the grape cultivation process, which contributes 8.39% of the total impact. This is consistent with previous wine LCAs, as viticulture is often attributed as one of the highest impacts. This can be primarily attributed to the amount of fungicide, pesticide, and fertilizer compounds required to maintain the health of the crops [26
The third highest impact was associated with the production of electricity for winery operations. This was the case primarily due to the electricity generation by the 151 kW solar array that provided all of the winery’s electricity needs overall. Compared to the other two wineries in this study, the Medium winery had the highest electricity consumption per bottle of wine. This results in the electricity generation and consumption impacts comprising nearly 7% of the total climate change impact of the wines produced at the Medium winery. The processes for blending the finished wine as well as harvesting the grapes from the vineyard were the next two highest impacts, although their impacts each only amount to 2% of the aggregate GHG emissions of an average bottle of wine produced by the Medium winery. The rest of the processes from cradle to gate together contribute to just over 1% of the total impact.
For the Large winery, the total GHG emissions associated with the production of an average bottle of wine is 0.617 kg CO2eq
, which is the lowest result of the three Finger Lakes case studies (Figure 5
). The Large winery produces an average of more than 500,000 bottles of wine per year, a much higher production volume than either of the other two wineries. This suggests an economies of scale effect for the climate change impact of a bottle of wine produced using the practices of the three wineries investigated.
The highest impacts for the Large winery can be attributed to the bottling phase, which includes the production of the glass bottle as well as the transportation of the bottles from the manufacturer to the bottling location on-site. This is often the highest contributor to greenhouse gas emissions in wine LCAs, due to the impacts of producing the glass material [26
]. The process modeled in this study represents 75.0% of the total cradle-to-gate impacts (Figure 6
), with 99.6% of the process emissions resulting from the glass bottle production.
Transporting the bottles to the winery can present significant impacts, as seen with the Medium winery, which transported an average of 1278 km farther than the Large winery. However, despite also including the transportation of the bottles to the Large winery, the impact of bottling is only 0.0016 kg CO2eq bottle-1 higher than the bottling impact of the Small winery. This indicates that the impacts associated with transporting bottles the distance between the Large winery and the bottle manufacturer are minimal compared to those of other processes. In the results for all three wineries, the production of the glass bottle represents the overwhelming majority of the life cycle GHG emissions of a 0.75 L bottle of wine from this region.
The second highest impact for wines from the Large winery is associated with the cultivation process, which comprises 18.0% of the aggregate climate change impact (Figure 6
). This can be directly attributed to the amount of Timothy hay used for fertilizer on the vineyard and the use of sulfur as a broad-spectrum fungicide. The Large winery is also the only one of the three Finger Lakes sites for which the existing drainage system was modeled due to sufficient detail, although with the long lifetime of the high-density polyethylene (HDPE) pattern tile, the impacts associated with this system only contributed 0.0012 kg CO2eq
. Despite being the second most impactful process, the impacts of viticulture are four times lower than those at the Small winery.
The third highest impact for the Large winery results from the winery’s use of propane for heating and as a fuel for various pieces of machinery (such as forklifts) on-site. The Large winery was the only winery in this study to use propane in its operations. The impacts associated with the use of the propane amount to approximately 0.021 kg CO2eq
, which is just over 3% of the life cycle impact of a bottle of wine (Figure 6
While electricity generation by solar panels is the next highest impact for the Large winery, this impact contributes a lower percentage of the life cycle GHG emissions than the same process for the other two Finger Lakes wineries. The impacts associated with this solar electricity generation add less than 2% of the cumulative impacts, the equivalent of under 0.011 kg CO2eq bottle−1. This is a direct result of the relatively lower electricity consumption by the Large winery per bottle of wine, which amounts to approximately 0.25 kWh per bottle of wine. This is much lower than the electricity consumption of the Small and Medium wineries at 1.24 and 1.12 kWh per bottle, respectively. It must be noted here, however, that the Large winery does include propane as an additional energy input, which has the potential to account for this discrepancy. The remaining parameters combined represent less than 2% of the total life cycle GHG emissions of a bottle of wine produced at the Large winery.
In addition to the analysis based on the current operating conditions at each of the three case study wineries, alternate scenarios substituting the solar panel-generated electricity with the electricity mix from the regional grid were modeled in order to determine the influence of solar power in winemaking processes for these wineries relative to utilizing electricity from the grid. For the Small winery, having electricity provided by the grid increases life cycle GHG emissions by 0.127 kg CO2eq
or 12.3% from the baseline. For the Medium winery, grid-based electricity leads to a 0.145 kg CO2eq
or 19.5% increase. For the Large winery, a 0.031 kg CO2eq
or 5.02% increase can be observed when switching from solar-based electricity to grid-sourced electricity. The carbon emission intensity of electricity from the grid in the Finger Lakes is relatively low compared to other regions of the United States because of the prevalence of hydropower and nuclear energy, followed by natural gas [29
]. Although these changes in carbon footprint are modest, this suggests that increasing the use of solar panels for electricity could be advantageous in the Finger Lakes winemaking facilities to reduce their GHG emissions.
Overall, for the wineries included in the Finger Lakes case study, the process in the life cycle of a bottle of wine which contributes the most to climate change is bottling, and in the case of the smallest wineries, cultivation, in the way that the processes were defined (Figure 7
). This is consistent with the conclusions of previously published wine LCAs and supports the basis for studies that evaluate the influence of lightweight packaging and alternatives to glass, as well as organic and low-intensity agricultural practices (e.g., [11
]). However, organic and low-intensity agricultural practices might not be as influential in reducing GHG emissions, as the Small winery most closely follows these practices compared to the Medium and the Large winery, and because this may have led to the relatively lower yield of grapes per hectare per year reported by the Small winery. This in turn affects the life cycle climate change impact of wine. The results also suggests an economy of scale effect, where intensification may reduce life cycle GHG emissions.
3.2. Sensitivity Analyses
A sensitivity analysis was performed for all variable input parameters for each of the three wineries by changing each input, one at a time, to its maximum and minimum value and evaluating the subsequent change in the life cycle environmental impacts of a bottle of wine. Similarly, six other wine LCA studies performed sensitivity analyses to determine the impacts of changing system inputs [1
The results of the Small winery case study are most sensitive to the life cycle climate change impact of solar-generated electricity (Figure 8
). If the impact per kilowatt-hour were at the maximum value modeled (0.183 kg CO2eq
/kWh), the life cycle climate change impact for the Small winery would be 16.7% higher than the baseline impact. The amount of electricity used in the production of one bottle of wine is just barely (0.82 kWh bottle-1
) higher than the electricity used per bottle for the Medium winery, so investment in higher-efficiency machinery may be a worthwhile endeavor to reduce the carbon footprint of wines from the Small winery in the future.
The second most sensitive variable parameter for the Small winery is the mass of grapes harvested per hectare per year. As this is one of the parameters involved with the calculation to determine the number of bottles produced in a year, the sensitivity of this variable parameter is unsurprising. With the maximum mass harvested per hectare modeled in this LCA case study, the total climate change impact decreases 7.18% from the baseline. In order to minimize the life cycle greenhouse gas emissions associated with the production of their wines, the Small winery may prioritize maximizing the mass of grapes harvested from each hectare. However, reaching this goal may involve implementing different cultivation practices which would themselves affect the life cycle climate change impact of the system. Furthermore, this yield per hectare may be difficult for the winery to control, and efforts to maximize this value are typically already undertaken for economic reasons, regardless of environmental impacts.
The third most sensitive variable parameter for the Small winery is the mass of grapes needed to produce one finished bottle of wine. This correlation is logical, in that the more grapes required per bottle of wine, the higher the GHG emissions associated with the production of the bottle of wine. The baseline value for the Small winery was 1.134 kg of grapes per bottle; this was varied to 0.964 and 1.304 kg of grapes per bottle for the sensitivity analysis. The Medium and Large wineries used a slightly lower mass of grapes per bottle at 1.20 and roughly 1.12 kg bottle−1
, respectively. These masses of grapes may be higher in wines from the Finger Lakes region than those used for other wines; for example, a study of French and Spanish wines indicated that each kilogram of grape was considered equivalent to a 0.75 L bottle of wine [9
]. However, these wines were mostly red wines instead of the white varietals common to the Finger Lakes. Still, the amount of grapes required to produce a bottle of wine in the style of the winery in question is often something that cannot be readily changed without altering the flavor profile and style associated with the wine, and therefore minimizing this value would likely be unrealistic for the Small winery to undertake.
The next two most sensitive input parameters are the area of the vineyard itself and the mass of the Timothy hay utilized as fertilizer on this vineyard. The sensitivity of the area of the vineyard is due to the range of values assumed—the area of vineyard utilized was increased slightly in 2014, though the newest land is the area that occasionally requires irrigation. Therefore, for the purposes of this study, the minimum value for the area of the vineyard was assumed to be the area of land that was vined before 2014, as if there had been no land added. As the intention was to determine the environmental impacts of the average bottle of wine produced at the Small winery, the lower value was assumed to represent the impacts of wines produced before the expansion. If 100% of the vined area (the maximum value for the variable parameter) produced the modeled baseline mass of grapes per hectare, the overall environmental impacts would be lowered by 6.81% (Figure 8
Although the carbon footprint of wines from the Small winery is sensitive to the mass of Timothy hay used, the Timothy hay is intended to account for nitrogen deficiencies in the soil and reducing the amount of fertilizer has the potential to lead to smaller harvests. This would in turn lead to a higher environmental impact. In addition, the Small winery only spreads hay on every other row, so it is reasonable to assume that the amount of hay applied for fertilizer is necessary to meet the nutritional needs of the vines. The rest of the modeled input parameters showed minimal influence on the total GHG emissions, affecting these impacts by 0.82% at most when changed to their minimum or maximum values.
For the Medium winery, the cradle-to-gate GHG emissions of a bottle of wine were most sensitive to the distance that the empty bottles were transported from a supplier to the winery (Figure 9
). This was expected, as the bottles were sourced from a wide range of locations, from as close as Pennsylvania to as far as Mexico. At the maximum transportation distance for the bottle (4200 km, from Mexico), the baseline LCA results increased by 18.5%. At the minimum distance (337 km from Pennsylvania), the impacts of a bottle of wine decreased 6.14% from the baseline LCA result. In order to reduce the carbon footprint of their wines, the Medium winery could source their bottles from locations that are a smaller distance from the winemaking facility. There is potential to locate suppliers in the region, as the Small winery and the Large winery both utilize a single bottle manufacturer which would be less than 32 km away from the Medium winery.
The second most sensitive parameter for the Medium winery is the life cycle climate change impact of the electricity generated from their solar panels. The range of values for this parameter was obtained from a harmonized LCA of electricity generation from crystalline silicon solar photovoltaic systems [27
]. If the value for the impact of solar power were assumed to be the maximum (0.183 kg CO2eq
), the life cycle GHG emissions increase by 20.8% (Figure 9
). The sensitivity of the impacts of electricity generation for the Medium winery emerges from the relative demand on electricity for winemaking processes, as the electricity usage per bottle is the highest of any of the three Finger Lakes wineries being studied. Its influence suggests that performing regular maintenance on solar panels in order to extend their lifetime and maximize efficiency, installing higher-efficiency machinery for winemaking processes, and increasing the capacity for passive processes (i.e., the outdoor cold stabilization tanks) could reduce the carbon footprint of wines from the Medium winery.
The third most sensitive variable parameter for the Medium winery is the mass harvested per hectare each year. This parameter directly influences the production volume, with smaller harvests resulting in a lower total number of bottles produced. If the winery experiences a year in which the harvest yield matches the minimum value modeled of 4.48 Mg ha−1 year−1, 16.5% higher life cycle GHG emissions per bottle of wine result. Therefore, the Medium winery may also prioritize efforts that maximize the amount of grape harvested from each hectare of vineyard. However, the size of the viable crop is dependent on several factors outside of the winery’s control as well (e.g., level of precipitation, unusually cold seasons, etc.) and therefore the mass harvested can be controlled by the Medium winery to a limited extent.
The mass of grapes used in each bottle, the number of fungicide applications and mass of fungicides used, and the mass of the empty bottle also influence the life cycle GHG emissions of wines from the Medium winery. A decrease in any of these values leads to a corresponding decrease in the carbon footprint. Therefore, the Medium winery could reduce its carbon footprint by reducing these masses and the number of fungicide applications. However, higher priority should be placed on the more sensitive parameters of the bottle transportation distance, electricity generated from solar panels, and the mass of grapes harvested per year. The rest of the parameters that were varied in the sensitivity analysis resulted in a less than 0.65% difference from the baseline LCA results when changed to their minimum and maximum values.
The most sensitive parameter for the Large winery is the mass of grapes harvested annually per hectare. This variable is influential in determining the number of bottles produced each year, and thus it affects the life cycle GHG emissions that are scaled to one bottle of wine. If the mass of the annual harvest decreases by 15% (to the minimum value modeled), the overall GHG emissions associated with the life cycle of a bottle of wine increase by 20.8% (Figure 10
The second most sensitive parameter for the Large winery is the mass of the empty wine bottle. While the impacts of transportation are minimized due to the location of the bottle manufacturer in a neighboring town, the impacts associated with transportation are still dependent on the mass of the bottle, as is the production of the glass in the first place. The lightest bottle used by the Small and Large wineries has a mass of 425 g, which is slightly lighter than the masses given in previously published studies. This is due to the design by the manufacturing company, which advertises an “eco-glass” product line of bottles that is lighter than conventional glass (Waterloo Container, Waterloo, New York, NY, USA). The Small winery explicitly mentioned the “eco-glass” line of bottles from this manufacturer as the source of their product, which has the same mass as the bottle weighed on-site at the Large winery. Therefore, it is assumed that the bottles used by the Large winery are also from this product line and are already lighter than conventional bottles. When the impacts associated with a finished bottle of wine are calculated using the minimum value for the mass of the glass bottle, they are 3.37% lower than the baseline impact, whereas if the maximum bottle mass is used, the impacts increase by 5.05% (Figure 10
). In order to minimize impacts associated with the mass of the wine bottle, the lightest viable option should be the one selected.
The last three parameters which have considerable sensitivity for the Large winery are three of the same seen for the Small winery: the mass of grapes used in a single bottle of wine, the carbon footprint of electricity generated by solar panels, and the mass of Timothy hay used for fertilizer. The lower sensitivity to the impacts associated with solar energy are likely driven by the fact that the Large winery uses approximately 80% less electricity per bottle than the other two wineries studied. However, the Large winery does use propane for energy on site in addition to electricity from solar panels and diesel in vineyard equipment. For the use of Timothy hay for fertilizer, changing the amount used to its maximum or minimum value only results in an impact that is 2.65% higher or lower than baseline GHG emissions (Figure 10
). The minimum amount of hay needed to maintain reasonable nitrogen levels in the soil should be what is applied, but efforts to reduce the carbon footprint of wines from the Large winery should prioritize more sensitive parameters.