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Energy Use, Efficiency, and the Future

Garrett Hardin who originated the idea of the Tragedy of the Commons, summarizes the two laws of Thermodynamics in terms of human significance as:

"You can't win, you are sure to lose;
and - you can't get out of the game."1

Whether we can get more "out of the game" is the central question of energy production. The examples above show what a small fraction of the input potential energy is actually used as output work. Designing for energy efficiency means in order to get a higher ratio of output, the input needs to become a central concern of intelligence design and practice.

Most of the energy planning is done by looking at the supply side. We examine how we can increase the supply of the resource in question, rather than by asking how the demand side (all our uses of energy) can be managed. Energy availability and use are good indicators of the standard of living in our technological world. In the U.S. the "average consumption per capita" is 55 barrels of oil. In the poorer countries, the consumption is 6 barrels per year. Figure 20 shows the projections of world energy supplies from 1970-2020. The increased coal supply is based on mining coal that is harder (and hence more costly) to extract.

Figure 20: World Energy Consumption by Fuel Type, 1970-2020.
Sources: History: Energy Information Administration (EIA),
Office of Energy Markets and End Use, International Statistics
Database and International Energy Annual 1997, DOE/EIA-0219 (97) (Washington, DC, April 1999). Projections: EIA, World Energy Projection System (2000).

Demand-side management instead of or in addition to supply side management would mean a focus on increasing efficiency of use and considerations of how to reduce the demand. The CAFE (Corporate Average Fuel Economy) standards legislated in the U.S. in 1980's required a certain level of fuel efficiency of U.S. automobiles. By demanding that the corporations figure out an overall fuel rating for all their fleets, the decisions on design and distribution of big and small cars in the total fleet were left to the industry, as long as the total corporate fuel economy goals were met.

There are also some efforts to recapture some of the "waste energy" from the processes of energy generation. Co-generation described in Figure 21 is an example of industries working together to see how exchanges of energy and materials could minimize waste.

Figure 21: Co-generation.


An Example of "Waste Power" Use
An unusual example of such a partnership network in Denmark is show in Figure 22. It is the result of 10 years of planning, and involves exchange of water, steam, gas, and gypsum.

Figure 22: Industrial Ecosystem.
Source: Allenby and Graedel, "Defining the Environmentally Responsible Facility."
Measures of Environmental Performance and Ecosystem Condition. National Academy Press: Washington, D.C.

Four companies (a power plant, a refinery, a gypsum facility for producing wall board, and a pharmaceutical plant) effect the exchange shown in Figure 22. The "waste" products from the power station (including heat in the form of warm water) are used to warm the greenhouse and other facilities. Such a co-generation system provides an industrial ecosystem with a much higher efficiency for overall energy use than if any of the organizations had organized independently for their material and energy needs. The ten years of planning required shows that such processes take time to explore the possibilities, develop the relationships, then plan and execute.


[1] Hardin, Garret. Filters Against Folly: How to Survive Despite Economists, Ecologists, and the Merely Eloquent. Viking Press, 1985. (p. 173)




  ©Copyright 2003 Carnegie Mellon University
This material is based upon work supported by the National Science Foundation under Grant Number 9653194. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.