4.4 Wineries / Breweries - Brandy Aging

Category 32

4.4.1 Introduction

Category 32 is an area source that accounts for ethanol (or TOG) emissions from aging of brandy in the San Francisco Bay Area (SFBA).

Brandy is produced from a distillation process that separates ethanol and other volatile substances from wine and fermented juices. The brandy is then aged for a period of two to ten years. During the brandy aging process, usually, in 50-gallon oak barrels, there is considerable amount of ethanol that is absorbed by the wood of the barrels. This ethanol is ultimately released from the barrels into the atmosphere in the form of evaporation.

The organic emissions from winery/brewery combustion sources are accounted for as ‘point/permitted sources’ and reported separately under industrial sources (Category 31) in the current inventory (with a base year of 2015).

4.4.2 Methodology

Category 32 is considered an area source category since it covers facilities / emission sources that are not directly permitted by the District, and hence not systematically cataloged. Emissions for area source categories are determined using the formula:

Current Year Emissions = Base Year Emission X Growth Profile, and,

Base Year Emission = Throughput X Control Factor X Emission Factor

where,

  • throughput or activity data for applicable base year(s) is determined using a top-down approach (e.g. state-, national-level data);
  • emission factor is derived from general literature, specific literature and reports, and/or source testing results provided by Air District staff;
  • control factor (if applicable) is determined by District and state rules and regulations in effect;
  • and, historical backcasting and forecasting of emissions is based on growth profiles as outlined in the Trends section of this chapter

The methodology for deriving emissions from wine and brandy aging is consistent with California Air Resources Board (CARB) Emissions Inventory Code (EIC) for Wine Aging # 420-410-6090-0000 (60467)39, as well as San Joaquin Valley Air Pollution Control District’s (SJVAPCD) 2007 Area Source Emissions Inventory Methodology40. More details on throughput, county distribution, emission factors and controls is provided in the following subsections.

(a) Activity Data / Throughput

The throughput for this category is barrels of brandy aged. Data on SFBA county-specific barrels of brandy aged is only available for year 1990 (total of 64,321 barrels; see Table III1). This data is adjusted for all future years by scaling this quantity to the ratio of amount of wine grapes crushed in California in a given year to the amount crushed in year 1990 which are both derived from US Department of Agriculture’s National Agricultural Statistics Service (USDA NASS) Grape Crush Reports41. An assumption is made that ratio of wine grapes crushed in SFBA in various years compared to year 1990 remain in the same proportion as the statewide ratios calculated above.

(b) County Distribution / Fractions

The county distribution of aging brandy barrels from year 1990 is held constant for all future years. Napa (>60%) and Sonoma (>30%) counties account for most of the throughput in the SFBA.

(c) Emission Factors

An emission factor for a 50-gallon brandy barrel is derived by the Wine Institute. The assumption is made that brandy is 120 proof (60% alcohol) on average; and alcohol is lost during aging at a rate of 2.5% per year per barrel. This results in an emission factor of 4.964 lbs of ethanol per barrel of brandy per year.

(d) Control Factors

Presently, no known District regulations or controls have been instituted on aging loss from brandy barrels to prevent ethanol emissions going into the atmosphere.

(e) Speciation

This source category reports Total Organics Gas (TOG) emissions. Ethanol is a reactive Volatile Organic Compound (VOC). All ethanol emissions are considered Reactive Organic Gases (ROG). Hence the ROG: TOG ratio is equal to 1.

4.4.3 Changes in Methodology

The only major changes in methodology made in this version is the way activity data has been estimated. The activity data in the BY2011 EI was based on scaling SJVAPCD throughput on aging brandy barrels2 to estimate equivalent SFBA activity. This time around, the throughput is based on scaling grape crush data of the state and SFBA for various years. Wine grape crush data is a more direct indicator of barrels of brandy produced and being aged.

4.4.4 Emissions

A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.

The total TOG emissions for 2015 from the brandy aging source category 32 is ~300 tons/year which makes it a minor to mid-tier source of TOG emissions in the SFBA.

4.4.6 Uncertainties

The wine aging emission factor has not seen any evolution since year 1992 so there is a fair amount of uncertainty as to the accuracy and representativeness of the ethanol emission factor to today’s barrel design and build. There is some variation in the proportion of grape crushed for wine-making in SFBA each year as compared to the California tonnage, but in this methodology that proportion is assumed constant. That assumption adds some more uncertainty to that estimate.

4.4.7 Contact

Author: Abhinav Guha

Reviewers: Tan M. Dinh and Yuan Du

Last Update: November 06, 2023

4.4.8 References & Footnotes

  1. CARB. 1992. Areawide Sources, Section 5.2 Food and Agriculture, Wineries, Aging. http://www.arb.ca.gov/ei/areasrc/fullpdf/full5-2.pdf.↩︎

  2. SJVAPCD. 2009. 420 - Food and Agriculture - Wine and Brandy Aging. https://www.valleyair.org/Air_Quality_Plans/EmissionsMethods/MethodForms/Current/WineBrandyAging2007.pdf↩︎

  3. California Agricultural Statistics Services. 2020. Grape Crush Final Reports, 1990-2020. https://www.nass.usda.gov/Statistics_by_State/California/Publications/Specialty_and_Other_Releases/Grapes/↩︎

  4. Wine Institute. 2020. California and US Wine Production. https://wineinstitute.org/our-industry/statistics/california-us-grape-crush/↩︎

  5. Association of Bay Area Governments. 2019. Plan Bay Area 2040. http://projections.planbayarea.org/↩︎