Technological Trajectories and the Human Environment (1997) / Chapter Skim
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Freeing Energy from Carbon
Freeing Energy from Carbon
Pages 74-88
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From page 74... ...
Growth in output in an economic system with suitable incentives tends to bring positive returns of its own. This process is sometimes referred to as "learning by doing." Analysis of learning curves in a range of industries, beginning with the manufacture of aircraft, has provided ample evidence that the costs per unit of output decrease rapidly at a rate proportional to the doubling of the output (Argote and Epple, 1990; Christianson, 1995~.
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From page 75... ...
Rising carbon dioxide emissions are the main contributor to fears of global climatic change. This and other environmental concerns associated with carbon makes energy free from carbon a highly desirable goal for the energy system.
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From page 76... ...
factor inputs and is embedded in most materials, products, and services, decreases in specific energy requirements can also decrease the intensity of materials use. The carbon content of energy and the subsequent carbon dioxide emissions form the largest single mass flow associated with human activities, excepting water.
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From page 77... ...
energy requirements per unit of value added, which is often called energy intensity. Available data allow us to assess with reasonable confidence the trend for each of these factors since the nineteenth century for major energy-consuming regions and countries, such as the United States and the United Kingdom, and thus for the world as a whole as well.
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From page 78... ...
The overall tendency is toward lower energy intensities, although paths of energy development in different countries have varied enormously and rather consistently over long periods (Figure 3~. For example, France and Japan have always used energy more sparingly than the United States, the United Kingdom, or Germany.
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From page 79... ...
The major determinants of energy-related carbon emissions can be represented as multiplicative factors in a simple equation. Placing carbon emissions on one side, on the other we have population growth, per capita value added, energy consumption per unit of value added, and carbon emissions per unit of energy consumed (Yamaji et al., 1991~.
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From page 80... ...
Together, the five countries account for about 45 percent of global primary energy consumption and more than 40 percent of energy-related carbon emissions. To determine more precisely the various causes and determinants of the decreasing carbon intensity of energy, we disaggregate the energy system into its three major constituents: primary energy consumption, energy conversion, and final energy consumption.
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From page 81... ...
Let us now compare the carbon intensities of final, primary, and conversion energy for the United States, Japan, France, China, and India in recent decades (Figures 5 through 7~. Steady reductions in the carbon intensity of final energy in all five countries stand out above all.
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From page 82... ...
1.1 a_ O 1.0 ~ 0.9 a' ._ . (n ~ 0.8 o <~5 0.7 0.6 0.5 Primary China India U SA Japan ~ France 1 1 1 1 1 1 1 1960 1965 1970 1980 1985 1990 FIGURE 6 Carbon intensities of primary energy, expressed in tons of carbon per ton of oil equivalent energy (tC/toe)
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From page 83... ...
Such shifts would align their energy systems with those of the more industrialized countries. Focusing on the United States and Japan, we see that the carbon intensity of primary energy exceeds that of final energy, with conversion intensity the highest of the three.
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From page 84... ...
This strategy to achieve low carbon emissions is completely internal to the energy system and fundamentally decoupled from the consumer. Nevertheless, the relatively smooth improvement in final carbon intensity is similar to that observed in Japan and the United States.
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From page 85... ...
to be the dominant source of energy during the first decades of the next century, although oil should maintain the second largest share until the 2020s. Such an exploratory look requires additional assumptions to describe the later competition of potential new energy sources such as nuclear, solar, and other renewables that have not yet captured sufficient market shares to allow reliable estimation of their penetration rates.
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From page 86... ...
A methane economy offers a bridge to the noncarbon energy future consistent with both the dynamics of primary energy substitution and the steadily decreasing carbon intensity of final energy. As nonfossil energy sources are introduced into the primary energy mix, new energy conversion systems would be required to provide zero-carbon carriers of energy in addition to electricity.
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From page 87... ...
Hydrogen has the lowest mass of all atoms, and its use would radically reduce the total mass flow associated with energy activities and the resulting emissions. Electricity is free of material emissions, and the only product of appropriate hydrogen combustion is water.
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From page 88... ...
1988. Carbon dioxide emissions in a methane economy.
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