Biomedical Engineering Reference
In-Depth Information
industrial accidents ever known today. Because large conventional dammed-hydro facilities
hold back large volumes of water at high potential energy, a failure due to poor construction,
terrorism, or other causes can be catastrophic to downriver settlements and infrastructure.
Dam failures have been some of the largest man-made disasters in history. Also, good design
and construction are not an adequate guarantee of safety. Dams are tempting industrial
targets for wartime attack, sabotage, and terrorism, such as Operation Chastise in World
War II.
The failure of a system of dams including Banqiao Dam and Shimantan Dam in Henan,
China, directly resulted in the deaths of 85,000 people in 1975 (Yi S, The World's Most Cata-
strophic Dam Failures: The August 1975 Collapse of the Banqiao and Shimantan Dams, in
Dai Q, The River Dragon Has Come!, M.E. Sharpe, New York, 1998). Millions were left home-
less. Also, the creation of a dam in a geologically inappropriate location may cause disasters
like the one of the Vajont Dam in Italy, where almost 2000 people died, in 1963.
Smaller dams and micro hydro facilities create less risk but can form continuing hazards
even after they have been decommissioned. For example, the small Kelly Barnes Dam failed
in 1967, causing 39 deaths with the Toccoa Flood, 10 years after its power plant was decom-
missioned in 1957.
15.4. CO 2 AND BIOMASS
As shown in Fig. 15.1 , the amount of CO 2 in the atmosphere is not variable over time as
a close loop is formed in nature. Sustainability is not disturbed if no net sink or source is
brought into the system.
Although humanity started in harmony with nature sustainably with using exclusively
biomass as the source of materials, chemicals, and energy, fossils have overtaken the role
as the dominant materials, energy, and chemical source since the industrial revolution. Petro-
leum, natural gas, and coal have been regarded as toxic waste materials from the distant past.
They have been the cheapest sources of energy, chemicals, and materials for over half
a century. Valorization of these waste materials has been the focus of research and develop-
ment and the achievements have been remarkable. The comfortable living standards of
humanity have been raised to a significantly high level especially in developed nations.
Our living standards today are not compatible with the primitive way of utilization of natural
resources. Simply “turning back the clock” is not an option. New sustainable state must be
found or will be evolved into. The choice we have is whether to choose one we like to be with.
While fossils have been fueling the raising comfortable standards of human living,
humanity has recognized the danger of utilizing fossils bring. For one, the amount of fossil
deposits on the Earth is finite. The time for the complete depletion of fossils is now predict-
able and lies in the foreseeable future despite new discoveries of deposits. Looking for
resources that we are used and away from the Earth is not foreseeable option. The continuum
or sustainability is thus at risk. The second, equally as important is that material flow is not
balanced in utilizing fossils. For example, CO 2 is generated when fossils are used as energy
source. Obtaining fossils from the “deep” underneath the earth and sending carbon dioxide
“up into” the atmosphere are the essence of fossil utilization. This is not a closed loop. The
“one-way traffic” only designed to bring carbon dioxide into the atmosphere from
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