Environmental Engineering Reference
In-Depth Information
Fig. 3.5
Relation between eco-footprint per capita and the Human Development Index (HDI).
(From Yoshida
2009
)
C is the level of consumption which is sustainable.
S is the level of consumption in 1 year which is sustainable.
We can assume that the level of consumption in 2000 exceeded the sustainable
level by 40 % and that the average ratio of consumption levels between developed
and developing countries was 100. If there is an increase in the population of devel-
oping countries of 3 billion by 2050, and developed country population stabilizes,
we can calculate the level in standard of living which could be the same for all and
still be sustainable by 2050. On these assumptions, two equations can be derived.
For 2000, 4.8 × A + 1.2 × B = 1.4 × S
For 2050 with each consuming a sustainable level of C, 7.8 × C + 1.2 × C = S.
By using these equations, C/A = 10 and C/B = 0.1 provides a solution. This sug-
gests that developing countries can increase their consumption 10 times, but at the
same time developed countries must reduce their consumption by 90 % to 1/10 of
the 2000 level by 2050. This is 'Factor 10'. To achieve Factor 10, developed coun-
tries can reduce consumption to one tenth; alternatively, if they can achieve a 5-fold
increase in the environmental efficiency of industrial products, a reduction of only
half would be sufficient.
Life Cycle Assessment
Based on the previous analyses, a recycling-based society
seems to be the only option to solve the resource problem. However, we have to
take into account the fact that recycling is not always the optimum if it needs more
resources or energy than producing new products. As one example let us consider
an issue raised (Takeda
2000
) concerning recycling of polyethylene terephthal-
ate (PET) bottles; he asserted that recycling should not be conducted because it
involves higher costs than producing directly from petroleum. On his analysis, a
new bottle costs 7.4 ¥, but the recycled bottle costs 27.4 ¥ when the costs of collec-
tion and transportation are included. His analysis would mean that recycling may
