Chemistry Reference
In-Depth Information
determined from meteorological data; this is the basic
water source magnitude. Because a minimum rea-
sonable level of per capita water use is about 100 l
day
-1
[13], the available non-residential amount
N
is:
Table 4.2
Proportion of energy from different sources
suitable for sustainable development of the synthetic organic
chemicals sector
Fossil fuel and
Non-fossil fuel and
Year
biomass energy (%)
biomass energy (%)
N
=
R
- 100
P
where
R
is the rainfall rate for the watershed (in l
day
-1
) and
P
is the population. (The average domes-
tic water use in developed countries is significantly
higher than 100 l day
-1
per capita, but from a sus-
tainability standpoint this constitutes a target worth
shooting for.)
The next step is to allocate
N
among non-
residential users: agriculture, industry, commercial,
etc. Ideally, such an allocation would be based on
minimum need for specific purposes, just as was
done above for individual residential use. There are,
however, no equivalent data for the great variety of
non-residential uses. As a pragmatic alternative, one
can perform the allocation on the basis of land occu-
pied, the idea being that the same amount of water
can be made available to each segment of land. The
approach is as follows:
2000
77
a
23
a
2025
60
40
2050
40
60
2075
20
8
0
2100
0
100
a
Contemporaneous global average values given in Ref. 14.
sustainable sources are petroleum, natural gas, coal
and biomass.
A facility moving towards sustainability is there-
fore one that is beginning a transition from unsus-
tainable sources of energy to sustainable ones. Given
the levels of fossil fuels still available, a reasonable
period for that transition is 100 years. A facility's
progress thus may be measured by the proportion
of sustainable sources in the fuel mix from which it
derives energy.
The average global proportion of contemporane-
ous sustainable energy sources is about 23%. In the
present work, a facility is defined as sustainable in
energy if it is meeting or exceeding the schedule
shown in Table 4.2. As Fig. 4.3 indicates, the transi-
tion from predominantly unsustainable energy
sources to predominantly sustainable ones then
should occur in about 2035-2040.
As with feedstock use, it is not possible in any
straightforward way to define a precise quantity of
energy use as sustainable or not. The difficulty is that
although the trends attributable to global change
seem increasingly clear, their magnitudes and im-
plications are less so [16,17]. Accordingly, although
decreased energy use is almost certainly desirable
from an environmental standpoint, the sustainabil-
ity of that use can be related only to the origin of the
energy supply and not to the magnitude of use.
(1)
Determine the total land within the watershed
(
) and the total land occupied by residential
uses (r).
(2)
Determine the land occupied by the facility
being assessed (F).
(3)
Compute the facility's sustainable water use allo-
cation (
A
):
F
N
A
=
-r
This procedure automatically allocates water for
common uses (parks, nature preserves, etc.) and
would assure a sustainable level of water use within
the watershed if complied with by all water users.
2.3 Sustainable use of energy
As discussed above in the case of chemical feed-
stocks, the use of fossil fuels is ultimately unsustain-
able because of supply considerations [14,15]. It
appears possible as well that use of any energy-
producing source that involves combustion and CO
2
generation may be constrained by global warming
concerns (e.g. the Kyoto Protocol). Thus, truly sus-
tainable energy resources can be regarded as fissile
materials, hydropower, solar power, wind power,
geothermal power and ocean power, whereas un-
2.4 Environmental resilience
The final element of the sustainability of a facility
refers to the capability of the ecosystems with which
it is in contact to receive any dissipated residues
without suffering significant degradation. This cri-
terion, easily stated, in practice has proved essen-
