Disposable Cups vs.
Reusable Cups
Solving the Carbon Intensity Question
In this short report, Carbon Clear
examines the environmental impact of
paper, polystyrene and ceramic cups
throughout their lifetime - including
manufacture, use, re-use and disposal. We
conclude that ceramic cups are the lowercarbon choice in most cases, and also the
most financially sensible option.
The installation of coffee vending machines and
water coolers in the office environment has led to
a significant increase in the use of disposable cups,
and therefore waste. Most reusable cups however
have higher embodied energy contenti.This has led
many companies to question the environmental
impact of different cup types, and to consider which
has the lowest impact.
The most common types of disposable cups
are paper and polystyrene foam cups. The most
common types of reusable cups are made from
glass or ceramic, with ceramic being the most
popular material.
Cup Materials
Paper cups are the least expensive and the most
widely used. Paper is recyclable; however paper
cups must be coated with a polyethylene plastic to
prevent damage to the cups from hot beverages.
Most recycling facilities are unable to separate
the polyethylene shell from the paper and these
cups end up in landfills where they eventually
decompose, releasing carbon dioxide and methane.
Polystyrene foam cups can be washed and reused
in theory, but are seldom reused in practice. They
can be recycled as well, however they are not
widely recycled due to lack of incentives to invest
in compactors and the logistical systems required
for recycling polystyrene economically. Unlike
paper cups, where the paper element of the cup
www.carbon-clear.com | © Carbon Clear
would biodegrade, polystyrene foam cups are nonbiodegradable and will remain intact in landfills for
hundreds of years.
Ceramic cups must be fired at high temperature
in a kiln during manufacture, but can be reused
hundreds or thousands of times. Ceramic cups can
be microwaved and refrigerated, however they are
fragile and need to be handled carefully to ensure
a long life. The ceramic shards do not decompose
readily and are not responsible for significant
greenhouse gas emissions on disposal.
Comparing The Options
Due to the huge difference in embodied energy, an individual disposable cup will always have a lower
carbon footprint than an individual ceramic cup. In addition, ceramic cups have to be washed before reuse.
The emissions associated with the water and energy used during washing also needs to be added to
the cups’ carbon footprint. However, a single ceramic cup is used in place of multiple disposable cups.
On average a ceramic cup is used 2,000 timesii before it breaks or is disposed. Therefore to allow a fair
comparison between the two, comparison of energy required for the number of servings throughout the
life of ceramic cup is more appropriate.
Figure 1 compares the energy required per 2,000 servings for paper, polystyrene and ceramic cups. The
‘break even counts’ shows that on average, ceramic cups must be used at least 31 times to justify a corporate
policy switch from paper to ceramic; and on average 354 times to justify a switch from polystyrene.
Table 2 shows total green-house gas emissions generated from energy use per 2,000 servings. The ceramic
cup clearly wins the water cooler debate, with the lowest energy requirement on a per serving basis. The
ceramic cup also has the fewest carbon emissions from energy use.
Similar to polystyrene foam cups, ceramic cups are non-biodegradable and therefore do not have emissions
from landfill. In addition to this, the use of ceramic cups avoids accumulation of disposable cups in landfills
as a single ceramic cup lasts several years and displaces the use of thousands of disposable cups.
2 | www.carbon-clear.com | © Carbon Clear
Financial Analysis
While a switch to ceramic cup proves to be the more environmentally responsible choice, Table 3 below
shows that it is also a good financial decision. A switch from polystyrene to ceramic pays back in one to two
months’ time while a switch from paper to ceramic pays back in two to three months’ time.
Carbon Clear Insight
Cup use is likely to constitute only a small part of a company’s carbon footprint. It is however very visible
to staff and other stakeholders, and so to engage on this issue can be an important and influential part of a
wider programme of carbon reductions.
This analysis found ceramic cups to be the lower-carbon and best value choice, but as with many issues in
the carbon debate it is sensitive to assumptions such as the lifespan of ceramic cups, and the energy used in
washing them. Even the source of electricity generation will affect carbon emissions and break even counts.
We hope however that this report has helped to highlight some of the issues around cup use, and the
process for comparing alternative choices and selecting the lowest carbon option. As always, we would
recommend that you use data specific to your company and situation so that you can make informed
decisions about the most effective way to reduce your carbon impact.
References
i
The sum of energy inputs required to manufacture a product.
ii
Average use of mug before disposal from - http://en.brinkwire.com/2082.
The embodied energy data has been taken from the Inventory of Carbon and Energy (University of Bath). The embodied energy for ceramic, paper
and polystyrene chosen for this study is 29MJ/kg, 43 MJ/kg and 100 MJ/kg respectively. The weight of the ceramic cup used is 400 grams while
the weight of paper and polystyrene cup are 10.2 grams and 1.9 grams respectively (from http://plasticfoodservicefacts.com/Life-Cycle-InventoryFoodservice-Products)
iii
iv
The electrical energy required per wash is 100 KJ/cup/wash. The efficiency of electricity generation is taken as 33%.
The energy used per 2000 servings has been used to compare plastic and paper cups over the lifetime of an average ceramic cup. The energy
expressed is in form of electrical energy and the electrical generation efficiency is taken as 33%.
v
The break-even count is calculated based on embodied energy.
vi
For emission calculation, the emission factors for electricity are for UK. The emission factors for oil and gas have been taken from DEFRA, 2011. The
breakdown of energy has been taken from Inventory of Carbon and Energy (University of Bath).
vii
viii
The emissions from paper in landfills is 1.87 kg CO2 (IPCC, 2007) from http://cmt.epa.ie/Global/CMT/emission_factor_sources.pdf
ix
The density of ceramic cups-3000kg/m3, density of polystyrene – 38kg/m3 and density of paper 400 kg/m3.
x
For payback calculation, four servings per day and 20 days per month have been used.
For more information on how to calculate the carbon impact of renewable or reuseable cups at
your company, and for all your carbon footprinting needs, please call us on 0845 838 7564.
3 | www.carbon-clear.com | © Carbon Clear