How Green is your Coffee?
Sanita Dhaubanjar ’13, Hannah Hitchhner’12, Sicong Ma’13
Mass and Energy Balance- Picker Engineering Program, Smith College
Life Cycle Inventory
Melissa Krueger, the owner of Elbow Room Café, is planning to roast her own coffee beans and is concerned about her air emissions involved in the process.
This LCA aims to outline where the performance of Elbow Room Café stands in comparison to coffee giant Starbucks at Northampton, who promotes various
environment friendly campaigns. In tracking the production of coffee the main focus will be on overall resource usage and the total air emissions for the two cafe.
Introduction
The functional unit of comparison is taken to be 14 oz of brewed coffee and the
mass, energy and emissions that pertain to that single cup has been calculated.
Amount of coffee bean used in both cases were obtained from collected data. Fig,1
& 2 outline the life cycle of one cup of coffee in each café. Mass and energy
balances were estimated based on an average estimate of the cups of coffee the
cafes sell per day and the overall energy they use up in one day. Roasting
calculations are based on one hour of machine runtime. For energy calculations,
the consumption section was controlled by the number of cups sold per day per
cafe, while all other calculations were based off amount of coffee used per cup.
Life Cycle Impact Assessment
The analysis focused on resources used and air emissions, mainly PM and VOC
emissions as they were found to be of major concerns in air regulation policies.
Limitations
This LCA neglected analysis of the farming phase, supplements that are use with
coffee consumption like cups, spoons, napkins etc assuming that both cafes obtain
these materials from the similar sources. Details like roasting type and brew type
have also been neglected due to lack of information. This analysis is very sensitive
to the input of coffee beans per cup and no. of cups sold per day in the cafes.
Resource Conservation (in Fig 3)
Figure 1. Mass-Energy Flowchart for
Elbow Room
Elbow Room has a comparative advantage
in resource consumption. Roasting
requires lesser energy for Melissa because
of the small capacity of her machines.
Small café size allows her to optimize her
energy use in consumption despite the
fact that she uses more beans per cup. The
proximity of her roasting plant to her café
reduced the fuel and related emissions.
Conclusion
Figure 3. Comparative advantage based on
Resource conservation.
Emissions Control (in Fig 4)
Figure 4. Comparative advantage based on
Emission Factors.
Figure 2. Mass-Energy Balance for
Starbucks.
Starbucks is more environmental friendly
as compared to Elbow Room. It has high
CO2 emissions due to fuel used in
transportation and emissions from using
natural gas in roasting machines. But the
use of Cyclones and Thermal Oxidizer
has abated its PM, NOx and VOC
emissions in roasting while Elbow Room
is at a huge disadvantage despite her
energy efficient business.
Starbucks energy use can be subtantialy
reduced by decreasing fuel consumption in
transportation or having a roasting plant
closer to the cafe. Both of these
improvements are hard and expensive to
achieve specially in short run. Elbow Room
can reduce its harmful emissions by
installing a thermal oxidiser or similar
technologies even in short run. Provided
Melissa installs a thermal oxidiser, Elbow
Room Coffee will be the greener (only in
Figure 5. Comparative advantage
terms of PM and VOC emissions) and more
based on Resource conservation.
energy efficient option.
Acknowledgements
Melissa Krueger, Managing Director, The Elbow Room Café
Chin Yen Tee, President, ESW
References
Coffee roasting air pollution [Internet]. [updated 2003 Oct 2]. Colorado (Co): Colorado
Department of Public Health and Environment Air Pollution Control Division; [cited 2010
Mar 5].
Starbucks Corporate Responsibility [Internet]. [updated 2007].Starbucks Corporation;
[cited 2010 Mar 20]