Environmental Engineering Reference
In-Depth Information
a second, not in minutes or hours (Lovins and Lovins 1982, 124), and several responses in rapid
succession may be required. Human reasoning and reflexes are usually inadequate to this task,
so there is heavy reliance on computerized assistance using programmed responses to discrete
stimuli.
Several characteristics of contemporary bulk electric power supply transmission grids make them
vulnerable to sabotage, including centralization of power supplies, long transmission distances,
continuity and synchronism in grids, high capital intensity, and long lead times (Lovins and Lovins
1982, 34-46). Increasing geographic separation over time between major energy facilities and their
customers concentrated most generating resources in very large capacity facilities in relatively
small areas remote from population concentrations they serve, made interconnected systems more
vulnerable to disruptions, and made the connecting transmission links between them longer and
more tenuous, exposing them to mishaps over greater distances. Facilities concentrated into small
areas make large targets. Long connecting links mean transmission lines were often built in rural
areas where they are difficult to keep under constant observation. Long transmission distances
impose additional capital and operating costs on bulk electric transmission systems, in addition to
transmission losses, while increasing vulnerability to all types of natural and unnatural hazards and
increasing response times for repair of damaged equipment. Because electricity cannot be easily
stored, centralized supply of electricity requires a continuous, direct connection from producer
to consumer, and interruptions of supply are instantaneously disruptive. “The grid exposes large
flows of energy to interruption by single acts at single points, and there is only limited freedom
to reroute the flow around the damage” (Lovins and Lovins 1982, 38). Electrical grids require
continuous, meticulous management because their operation must be kept synchronous. Depar-
tures from synchronism can seriously damage expensive equipment and cause a whole grid to
break down. This exacting requirement of synchronism raises serious problems for grid stability
(Lovins and Lovins 1982, 39).
The electric power industry is the most capital-intensive industry in the United States, and a
central power station is the most capital-intensive single facility in all industries (Edison Electric
Institute 1992). Capital intensity reflects the degree to which a project commits scarce resources,
and indirectly measures the difficulty of building or rebuilding it with limited resources. Capital-
intensive plants need to run almost continuously to pay interest on capital, thus placing a high
premium on the correctness of engineering expectations that they will prove reliable. External
interference can produce massive financial penalties as well as disrupting energy supplies. High
capital intensity commonly reflects a degree of complexity that hampers diagnosis and repair of
faults and limits available stocks of costly spare parts. Another result of high capital intensity is
limited ability to adapt to fluctuating demands. High demand may require new capacity which
a supplier cannot afford, while lower demand reduces revenues needed to keep paying off high
capital charges (Lovins and Lovins 1982, 43-45).
Long lead times required to build major energy facilities contribute to high capital cost and
investment risk. Uncertainties of forecasting future demand increase with longer lead times, thereby
increasing risk (Lovins and Lovins 1982, 45). Typical lead times reported by electric utilities in the
western United States for construction of additional thermal generating capacity increased signifi-
cantly after 1967, running 10 to 15 years for nuclear plants, 6 to 11 years for coal-fired plants, 4
to 8 years for combined cycle plants, and 3 to 7 years for combustion turbines in 1978 (Hamilton
and Wengert 1980, 69) before demand for new plants evaporated. Such long lead times require
foreknowledge of demand, technology, and financial costs further into the future, when forecasts
are likely to be more uncertain. Certainty is the first casualty of time in forecasting.
Electric transmission networks are large, complex, and difficult to operate successfully. They
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