Sustainable Limit Calculations

1
Sustainable Limit Calculations
2
Calculation of Global Sustainable Limiting Rate
of Carbon Dioxide Production
1. Virgin material supply limit To stabilize
the atmospheric CO2 concentration below
approximately 550 ppmv by the year 2100, global
anthropogenic emissions must be limited to about
7 to 8 x 1015 g ( 7 to 8 giga metric tons) of C
per year (IPCC, 1996).
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
3
Calculation of Global Sustainable Limiting Rate
of Carbon Dioxide Production
2. Allocation of virgin material Each of the
average 7.5 billion people on the planet over the
next 50 years is allocated an equal share of
carbon emissions. This translates to roughly 1
metric ton of C equivalents per person per year.
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
4
Calculation of Global Sustainable Limiting Rate
of Carbon Dioxide Production
3. Regional re-captureable resource base
Recycling of carbon in the form of permanent or
semi-permanent sequestration may eventually
possible through controversial techniques, not at
the moment.
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
5
Calculation of Global Sustainable Limiting Rate
of Carbon Dioxide Production
4. Current consumption rate vs. sustainable
limiting rate The U.S. on average produced 5.5
metric tons of C equivalents per person
(including emissions from land use change) in
2000, which is well beyond the global sustainable
rate of 1 metric ton of C equivalents per person
per year.
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
6
Lets calculate the sustainable limit for some
other material, as well.
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
7
Calculation of Global Sustainable Limiting Rate
of Zinc Consumption
1. Virgin material supply limit The reserve base
for zinc in 1999 was 430 x 1012 g (430 Tg), so
the virgin material supply limit over the next 50
years is 430 Tg / 50 years 8.6 Tg/yr.
2. Allocation of virgin material Allocating the
available zinc equally among all the worlds
population gives approximately 8.6 Tg/7.5
billions people 1.15 kg/(person.yr)
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9
8
Calculation of Global Sustainable Limiting Rate
of Zinc Consumption
3. Regional re-captureable resource base
Assume 30 zinc recycling rate. And, if the
system is in steady state and if 30 of the 1.15
kg/(person.yr) is recycled, then each person in
the region actually has (10.3)(1.15) 1.5
kg/(person.yr) of zinc available.
4. Current consumption rate vs. sustainable
limiting rate In 1999, the U.S. on average
consumed 1.6 Tg for a population of 260 million
people, which translates to a U.S. per capita
zinc consumption of 6.2 kg/(person.yr).
Source Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci.
Tech. 36(4) 523-9