Carbon dioxide is colourless, tasteless and odourless, but it’s everywhere and causing global warming. So how do we work out how much carbon is emitted to make a cup of coffee?
To work out the carbon emissions across the coffee supply chain, it’s necessary to compare very different activities. Fortunately, there are some established methods that allow us to calculate how much carbon dioxide (CO2) various activities, such as fertiliser use, transportation, packaging manufacturing, and roasting, produce.
This allows us to compare various processes, products, and behaviours. For example, which is the greater cause of carbon emissions: flying to origin to buy the coffee, roasting the coffee or preparing the coffee?
In this article we’ll unpack core concepts to answer these questions such as this. By understanding where our industry’s carbon emissions are greatest, we can identify where the greatest benefit from behavioural or technological changes can be made.
Getting the boundaries right
System thinking understands that a small action, such as drinking a cup of coffee, is part of a larger, and more complex, system of actions that make this one act possible. The coffee needs to be grown, processed, shipped, roasted, shipped again and brewed into coffee. So the carbon emissions calculate from the act of drinking a cup of coffee need to include the proportional impacts across all of these aspects.
But what about the fertiliser, or the grain pro sack, the cup, or your trip to work to make coffee for customers? Identifying a systems boundary is literally a discussion about where it’s best to draw the line.
There are some established conventions about what to include, which have now been set as standards. The British Standards Institution Publicly Available Specification 2050 (PAS 2050) specifies that while at least 95% of total emissions have to be included in the final impact figure, while material use that contributes to less than 1% of the carbon footprint can be excluded.
So, for example, coffee sacks are a tiny contributor to the total coffee CO₂ emissions, and they are commonly excluded from studies. While they pile up in busy roasteries, and it’s good to find subsequent uses for them, they are largely immaterial when considering the coffee industry’s carbon emissions.
By contrast cups contributes to more than one percent of total emissions for a cup of coffee. To be able to compare the carbon emissions of a grain pro sack versus a coffee cup, in order to be able to know what activities are included, we need to first calculate their respective embodied energy.
Understanding embodied energy
Cups are a good example to explain the concept of embodied energy, because they are comprised of one (or just a few) simple materials. By comparing the typical embodied energy of a porcelain, glass, paper and plastic, it is possible to work out a their respective carbon footprints. For example, the embodied energy of a:
- porcelain cup includes energy to heat the kiln to 1200 – 1400 °C
- glass to heat the furnace to circa 1600 °C
- take out cups include paper manufacturing, plastic-lining manufacturer, and the moulding of the cup
Embodied energy tables typically include the amount of energy to create 1 Kg of the material. So if we know how the mass of porcelain in a mug or quantity of glass in a glass (their total weight), or the mass of paper and plastic in a take-out cup, it is possible to calculate their respective embodied energy.
Many objects are significantly more complex. For example, to calculate the embodied energy of a roaster, espresso machine, or shop fit, requires specific itemisation of materials; measurement of their mass; and calculation of their total embodied energy.
The calculations are further complicated when considering processes, such as making a cup of coffee. To return to the cups example, a disposable take-out cup is single use so its total carbon emissions are largely its embodied energy; however a porcelain cup is used hundreds of times so it’s necessary to include aspects such as its washing.
The method for comparing the total carbon emitted in these cases is the Life Cycle Assessment.
Making informed decisions
The Life Cycle Assessment (LCA) has become the international procedure for calculating the environmental impacts of an item, for example ISO14040:2006. An LCA includes analysis for the acquisition of resources, its production, distribution and use, as well as the energy required to dispose or recycle the item.
There are now various consultancies, databases and resources for organisations and researchers wanting to perform a LCA. Despite the commonalty of the standard, because the system boundaries between studies and the assumptions that they contain can vary, it’s useful to either talk about specific examples, or broad generalities. Let’s start with a specific, simple example.
Most cafes, coffee shops and restaurants get their fruit and vegetables delivered in boxes, which are typically wooden crates, moulded plastic crates, or printed cardboard.
So which of these three options produces the lowest carbon emissions from their use?
- Wooden crates are the traditional option, made from a natural material, but are single use
- Plastic crates weigh over twice as much as a wooden crate, are manufactured from petrochemicals, but can be reused
- Cartons are made from cardboard, and can be recycled after use
A comprehensive life cycle assessment allows us to compare the embodied energy in each item, as well as energy required in its transportation, energy required to clean it between uses, and energy required to dispose of it after use.
Guess which box has the lowest carbon emissions – click to reveal
A study at the University of Stuttgart found:
- Good: Plastic crates – lowest carbon footprint, assuming 10x annual uses per crate
- Good: Wooden crates – circa 10% greater impact, but better if plastic crates aren’t regularly reused
- Worst: Cardboard boxes – twice as carbon intensive as plastic or wooden crates
Life Cycle Analysis of Coffee Cups
Building on these ideas, let’s return again to the use of coffee cups.
A Canadian study comparing ceramic cups, take-out paper cups and travel mugs found ceramic mugs to have the lowest environmental impacts. Reusable travel mugs were no better than take-out paper cups in a variety of scenarios because a) the level of embodied energy, and b) they typically require energy-intensive hand-washing between uses (CIRAIG).
A study conducted by the VTT Technical Research Centre of Finland had similar findings. This study also identifies that circa five percent of the total carbon emissions of a take out 8oz latte were from the the single-use take out cup and lid. The vast majority of carbon emissions are from the coffee and the milk.
The best option from a climate perspective from both the Canadian and the Finnish studies is to drink coffee from a ceramic cup. When a ceramic cup is used over 350 times it is clearly has the lowest environmental impacts, with the majority of its impact coming from washing between uses, rather than its manufacture.
When drinking coffee to go, reusable plastic cups have lower carbon emissions that a non-recyclable, single-use plastic-lined paper cup when re-used at least 20 times.
However, since reusable cups also require washing between uses, a change in behaviour from single use take-out cups to a reusable plastic cup results in a reduction of carbon emissions from drinking a flat white by just a percentage point or two.
Furthermore, using a re-useable takeout up with materials with high embodied energy, such as many of the options currently available, increases the number of re-uses required into the thousands – increasing the likelihood of greater environmental impacts than the use of a standard, paper take-out cup.
Take out cups are a great example of how the visual impact and environmental impacts often don’t match. Take-out cups are highly visible, and all too frequently littered. There has been tremendous effort by the industry and consumers to reduce their impacts from takeout cups, but the overall benefit is marginal, and certainly not sufficient to help the coffee industry reduce its high emissions levels by anywhere enough to reach the United Kingdom’s net zero greenhouse gas emissions by 2050.
Part of the benefit of doing maths around CO₂ emissions is the outcomes can be counterintuitive, and therefore highly instructive. The calculations show that while no contribution is too small in tackling this great challenge before us, no one should feel like they are doing their bit for the environment by using a reusable take out cup.
Also, as we pointed out at the time, our concern is that an inordinate amount of time and resources have gone into addressing the use of takeout cups, when it would have been better for the world if that same energy had gone into other more pressing or significant issues. Or, instead of the Environmental Audit Committee proposing a tax, it would have been better for them to have devised a proposal that would allow for the recycling of takeout cups. Recycling take-out cups reduces carbon emissions by circa 54%, making them (somewhat ironically given the committee’s proposal) one of the best environmental and practical options.
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Let’s focus our energies where real differences can be made
In With so many crises, what do we focus on? we headlined the fact that studies range from circa 5 Kg to 20 Kg of carbon emissions per Kg of roasted coffee. The variation in the outcomes is largely because of varying material inputs during coffee production, different transportation assumptions, and different preparation methods. However all these studies agree that coffee is a highly carbon insensitive product. And these studies draw their system boundaries in a way that excludes espresso machine embodied energy, electricity to run the air-conditioning and plant in a coffee shop, and – most significantly – which milk you opt for.
Since none of the studies specifically analysed what the specialty coffee industry would recognise as a typical supply chain, in the rest of this series we’re compiling insights from across these studies to paint a picture of carbon emissions in our portion of the industry to make the insights as actionable as possible.
To be able compare like-with-like, we have excluded the carbon emissions from milk and mylk (milk substitutes). But because this is one of the significant causes of carbon emissions, we’ll focus on this issue next article before return to an analysis of emissions from across the supply chain.
The good news is that while there are significant challenges ahead, there are also things that we can change today to lower the coffee industry’s carbon emissions. Now that we’ve unpacked the situation and the methodology, we’ll be exploring ways the industry can make a different over the coming weeks and at the at the Caffe Culture seminar.
In the meantime comments and feedback are welcome, we’re on all the usual channels.
Tackling coffee’s carbon footprint
What are you be doing to lower coffee’s carbon footprint? Will you be changing your coffee cup choice based on this information? Will you change your fruit and vegetable boxes?
References and reading
- PAS 2050 – Carbon Footprint, British Standards Institution
- ISO 14040:2006 Environmental management — Life cycle assessment — Principles and framework, International Organization for Standardization
- Embodied energy, selected data from the Inventory of Carbon and Energy (ICE) prepared by the University of Bath; Wikipedia
- The Sustainability of Packaging Systems for Fruit and Vegetable Transport in Europe Based on Life Cycle Analysis: Final Report; on Behalf of Stiftung Initiative Mehrweg
- An extended life cycle analysis of packaging systems for fruit and vegetable transport in Europe, Albrecht et al., 2013
- Smil, Vaclav (2014). Making the World Modern: materials and dematerialization, Wiley
- Reusable or Disposable: Which coffee cup has a smaller footprint?
- Taking a closer look at paper cups for coffee, VTT Technical Research Centre of Finland
- Life cycle assessment (LCA) of reusable and single-use coffee cups, CIRAIG for Recyc-Québec
- How long do porcelain cups last in your shop? Do they endure for more than 300 uses? If you’ve worked out the average number of uses a porcelain cup has before being broken in your shop, please let us know.
- How long does the average glass last in your shop?