Environmental Engineering Reference
In-Depth Information
System
Throughputs
Active Figure 2-12 Natural capital de-
gredation: the high-throughput
economies of most developed countries
rely on continually increasing the rates of
energy and matter flow. This practice
produces valuable goods and services
but also converts high-quality matter and
energy resources into waste, pollution,
and low-quality heat. See an animation
based on this figure and take a short
quiz on the concept.
Inputs
(from environment)
Outputs
(into environment)
High-quality energy
Low-quality energy (heat)
Unsustainable
high-waste
economy
Matter
Waste and pollution
Although changing to a
matter-recycling-and-reuse econ-
omy will buy some time, it does not allow ever more
people to use ever more resources indefinitely, even
if all of them were somehow perfectly recycled and
reused. The two laws of thermodynamics tell us that
recycling and reusing matter resources always requires
using high-quality energy (which cannot be recycled)
and adds waste heat to the environment.
not wasting matter and energy resources, recycling
and reusing most of the matter resources we use, and
stabilizing the size of our population.
Is there a better way out of our current dilemma? You
bet. The three scientific laws governing matter and en-
ergy changes suggest that the best long-term solution
to our environmental and resource problems is to shift
from an economy based on increasing matter and en-
ergy flow (throughput) to a more sustainable low-
throughput (low-waste) economy, as summarized in
Figure 2-13. It means building on the concept of recy-
cling and reusing as much matter as possible by also
reducing the throughput of matter and energy through
Sustainable Low-Throughput Economies
We can live more sustainably by reducing the
throughput of matter and energy in our economies,
System
Throughputs
Inputs
(from environment)
Outputs
(into environment)
Energy
conservation
Low-quality
energy
(heat)
Energy
Sustainable
low-waste
economy
Waste
and
pollution
Waste and
pollution
prevention
Pollution
control
Matter
Recycle
and
reuse
Matter
Feedback
Energy Feedback
Active Figure 2-13 Solutions: lessons from nature. A low-throughput economy, based on energy flow and mat-
ter recycling, works with nature to reduce the throughput of matter and energy resources (items shown in green).
This is done by (1) reusing and recycling most nonrenewable matter resources, (2) using renewable resources
no faster than they are replenished, (3) using matter and energy resources efficiently, (4) reducing unnecessary
consumption, (5) emphasizing pollution prevention and waste reduction, and (6) controlling population growth.
See an animation based on this figure and take a short quiz on the concept.
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