The Decision Tree

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Cradle to Grave

TDT 1.04 An interview with Dr Adam Carr

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Dr. Adam Carr runs the Coffee Science and Education Centre at Seven Miles Coffee Roasters  in Sydney, Australia. Dr. Carr previously worked as a researcher in chemical engineering, with a focus on high-temperature water technologies, so it was highly apt that he chose to transfer those skills to the coffee industry.


Dr. Adam Carr (left) with colleague Victoria Feijoo (right).


In 2018, he conducted a life-cycle analysis (LCA) focused on reducing the carbon dioxide (CO2) footprint of a typical cafe in Australia. It described some simple changes that cafes can implement to greatly reduce their environmental impact.

According to this LCA, up to half of the carbon emissions of a typical cafe come from the electricity needed to power the espresso machine. This suggests that, depending on your machine, reducing power consumption by turning it off overnight or switching to “eco mode” can have a big impact on CO2 emissions — and save you money too.

The next-largest contribution to the CO2 footprint, at more than a quarter, comes from the amount of cow’s milk used. Reducing milk wastage or encouraging the use of plant-based alternatives also has the potential to greatly reduce CO2 emissions.

By contrast, the emissions from disposable cups made up only 0.6% of the total calculated emissions. This information provides a useful example of how an LCA can help a business target the most effective interventions to reduce their carbon footprint. You can read the full summary of the findings from the LCA here.



BH – What prompted Seven Miles to undertake an LCA?


AC – When I started at Seven Miles, there was a lot of talk about the sustainability of paper cups and their impact on the environment, but I found no reliable facts around what the carbon footprint of any part of the coffee-making process was. So, as I have done LCAs in my former life as a research engineer, I did one to gain clearer insight!


BH – Did you work with a consultant or use an app, or did you compute the figures directly, by yourselves?


AC – I built it from the ground up. As a chemical engineer, my training is fundamentally about mass and energy balances, which is most of what LCAs are, at their core. Most programs also make assumptions that may or may not be erroneous, so to avoid bogus results and to gain greater clarity, we calculated most of the results in-house (i.e., those that weren’t already published in a reliable source).


BH – You mention that you found full ‘cradle to grave’ assessments for some processes in the literature, but others required some assumptions and computation (e.g., involving food for cafés). Where data wasn’t already available in the literature, how did you estimate or compute these numbers?


AC – The assumptions vary significantly, so it’s hard to give a catch-all answer! Some were simple: we had to assume the mass of a ‘standard egg’, which has an associated carbon footprint available in the literature for, for example, a 70-gram egg. It got more complicated when we needed to estimate the energy required to cook it (assume a natural-gas burner, burning at some line pressure, at a standard energy output, for a determined amount of time) and add the carbon emissions of this, on top of what it takes to farm an egg-laying chicken. This value was taken from an average of values from a range of websites and academic journals. Assumptions here also included whether the chickens were free range, battery farmed, the feed required, and such. And this was only to compute the carbon footprint on a bacon and egg roll! So, you can see how deep the rabbit hole can go with assumptions.

Some published papers on certain aspects are available freely on government websites (e.g., carbon emissions per BTU of energy produced in NSW, Australia), some in academic journals (e.g., Swiss ecopoint measurement values and analysis), and some were just computed based on logical assumptions.


BH – What would you do differently if you were going to conduct the analysis again?


AC – I’m fairly happy with the results we got, as they seemed to mirror [a published] life-cycle analysis available for the whole coffee life-cycle (we only looked at cafés for the blog, though I did go deeper later on). I think if we were to do it differently, we would do some experiments to confirm some of the assumptions about, for example, machines — looking at true energy consumptions for 1-, 2-, and 3-group machines, heat exchanger vs. multiboiler, etc., and back up the assumptions with real-world measurements.


BH – Would you expect to see similar results for all cafés?


AC – Yes, on the basis that (as shown from our results) over 50% of the environmental footprint for a café is due to the operation of espresso machines, and we published our results on a per-kilo-of-coffee-consumed basis. There may be as much as a 10% overall variation in the LCA per café,  assuming that cafés have a 100% difference in food wastage, but that’s ‘small potatoes’ compared with the overall footprint.


BH – What advice would you give to smaller businesses wanting to understand how to minimise their own footprint?


AC – As per our results, we do recommend idling your coffee machine in a low-power state overnight, or even turning it off. We found there is not an insignificant cost saving (as well as CO2 saving) to be had, even if it’s 5 hours until the café’s next service time.


BH – What changes did you make to improve your sustainability after conducting the LCA? Which of these changes gave you the most environmental ‘bang’ per buck?


AC – It’s funny, being a roastery and not a café, most of what we can do is to tell people what we found! However, as mentioned, I did take the LCA further to look at the whole coffee supply chain, and as a roastery we have now installed solar panels to offset all electricity usage for our operation, and we have implemented a bag, coffee pod, and coffee cup recycling program. As a whole, the waste in roasteries is very small compared with cafés or at the consumer level, but anything we can do to minimise our footprint is top of mind!


BH – Energy use seems to be the biggest source of emissions for most cafés. What are the easiest ways for cafes to reduce the energy use involved in coffee-making?


AC – As per the answer above, using a coffee machine with a built-in ‘eco mode’ can reduce power consumption at idle by 50%. This can save both money and carbon. Similarly, an interesting alternative is to use machines like the Übermilk/barissima to froth your milk. It heats using resistance coils rather than by steam, so significant energy savings can be had here. Also, as it dispenses milk directly and precisely, there’s lower food wastage, which can account for 26% of the footprint of a café (at least, in Australia). In fact, from some tests we found that you could save 20% on your milk consumption using precise milk dosing systems, which eases the burden on your wallet, as well as the environment. The best solutions always have this result, of course.