Working out the carbon footprint of a pint in a small brewery

Three scopes, in plain terms

Carbon accounting sorts emissions into three groups, called scopes. Scope 1 is fuel you burn on site: diesel in the generator, LPG or diesel in the boiler. It also includes leaks of refrigerant gases from your chillers. Scope 2 is electricity you buy from the grid. Scope 3 is everything else in your supply chain: malt, hops, packaging, transport, waste and the electricity your customers use to keep beer cold.

Scopes 1 and 2 are easy to measure because you pay the bills. Scope 3 is usually the largest and the hardest. Start with 1 and 2, then add the biggest scope 3 items.

Collect a year of data

You need twelve months of:

• Electricity bills in kWh.
• Diesel bought for generators and boilers, in litres.
• LPG, PNG or other fuel, in kg or standard cubic metres.
• Refrigerant top-ups from your chiller service records.
• Beer packaged in the same year, in litres.

If you run a brewpub, separate the kitchen and restaurant where you can. A pint's footprint should not carry the air conditioning for the dining room unless you decide that it should. If you do, say so.

Emission factors turn bills into carbon

Each fuel has an emission factor: the CO2 released per unit. Burning a litre of diesel releases about 2.7 kg of CO2. Burning a kilogram of LPG releases about 3 kg. India's grid electricity carries a factor of roughly 0.7 to 0.8 kg of CO2 per kWh. The Central Electricity Authority publishes the official figure. Check the latest edition and use it.

Refrigerant leaks matter more than their size suggests. Many common refrigerants have a warming effect hundreds or thousands of times that of CO2 per kg. A chiller that needs regular top-ups is a carbon problem as well as a maintenance one.

A worked example

Here is an illustrative small brewery making 1,000 hl, or 100,000 litres, of beer a year. The quantities are round numbers to show the method, not a benchmark.

• Electricity: 60,000 kWh x 0.7 = 42 tonnes CO2.
• LPG for the boiler: 8,000 kg x 3 = 24 tonnes.
• Diesel for the generator: 2,000 litres x 2.7 = about 5.4 tonnes.

That is about 71 tonnes, or 71,000 kg, for 100,000 litres: roughly 0.7 kg of CO2 per litre for scopes 1 and 2. A 500 ml serve carries about 0.36 kg before any ingredients or packaging are counted.

Add the big scope 3 items

For most breweries the next largest items are packaging and malt. Glass bottles are heavy and energy intensive to make, so single-use glass usually carries more carbon per litre than aluminium cans or returnable kegs. Malt carries the emissions of farming, drying and kilning. Transport adds more the further beer and ingredients travel.

Suppliers increasingly publish emission figures for their products. Ask your can, glass and malt suppliers for theirs. Where you cannot get supplier data, published average factors exist, but label them as estimates. Our guide to scope 3 emissions in beer explains the categories.

Use the number to decide, not to decorate

A first footprint is useful because it shows where carbon sits. In the example above, electricity is the largest share of scopes 1 and 2. That points straight at chiller efficiency, insulation on glycol lines and rooftop solar. Our guide to solar power for an Indian brewery covers sizing.

Keep the method the same each year so the trend is real. Turning bills into a footprint, then into a short list of projects ranked by carbon saved per rupee, is a planning skill that helps your sustainability story and your cost base alike.

Common mistakes in a first estimate

The most common mistake is mixing periods. Electricity bills for one year divided by beer from a different year give a meaningless figure. Use the same twelve months for everything.

The second is double counting. If your generator diesel is already in the boiler fuel total, do not add it again. The third is quietly leaving out awkward items, such as refrigerant top-ups or the kitchen's share of a brewpub's electricity. Write down what you included, what you left out and why. A transparent rough number is far more useful than a precise looking one nobody can check.

Finally, keep the units straight. Fuel is often billed in different units from one supplier to the next. Convert everything to the units your emission factors use before you multiply.

Your first step

Pull last year's electricity bills and fuel purchase records into one spreadsheet. Multiply each total by its emission factor and divide by litres of beer packaged. That is your first scope 1 and 2 figure per litre.

Common questions

What is the carbon footprint of a pint of beer?

It varies widely with energy source, packaging and scale. A small brewery can estimate its own figure from utility bills, fuel records and emission factors.

Which scope is biggest for a brewery?

Scope 3, covering ingredients, packaging and transport, is usually the largest. Scopes 1 and 2 are the easiest to measure first.

Where do I find India's grid emission factor?

The Central Electricity Authority publishes it. Use the latest edition, since the figure changes as the grid changes.