Energy and Human Ambitions on a Finite Planet, 2021a

17 Comparison of Alternatives 300
Table 17.1: Result of student weighting of the comparison matrix attributes. Notable gaps between scores appear between fossil fuels
<strong>and</strong> solar, between solar <strong>and</strong> the middle group, <strong>and</strong> between the middle group <strong>and</strong> the final group (right). When differences between
student scores <strong>and</strong> the nominal scores in Figures 17.1 <strong>and</strong> 17.2 exceed rounding error, the result is shown as a Δ, helping highlight the main
differences between student scoring <strong>and</strong> the nominal uniform-weight result.
Resource Score Δ Resource Score Δ Resource Score Δ
Gas 7.3 −0.7 Hydroelectric 3.6 Conv. Fission 1.6
Oil 6.8 −0.7 Algae/Biofuel 3.6 Geotherm. Depl. 1.4
Coal 6.7 −0.8 Geotherm. Elec. 3.3 −0.7 D–T Fusion 1.4
Solar Heat 3.2 −0.8 Wave 1.3
Tidal Capture 3.0 Ocean Thermal 1.3
Solar Thermal 5.4 Wind 2.9 Ocean Currents 1.0
Solar PV 5.1 Uranium Breeder 2.8 D–D Fusion 1.0
Artif. Photosyn. 2.8 Geotherm. Heat 0.7
Thorium Breeder 2.5 +0.5 Biofuel/Crops 0.4 −0.6
importance of the attributes—thus much of the behavior is “baked
in” based on the author’s judgment of color assignment. Still, shifting
emphasis on the attributes will shuffle the order somewhat, <strong>and</strong> that
itself is interesting. Any ambitious reader is welcome to mess with the
color scheme as well to see what happens.
17.4 Upshot: The Fossil Fuel Gap
The subjective nature of this exercise certainly allows numerous possibilities
for modifying the box rankings in one direction or the other.
The matrices embody some biases, but no attempt by anyone would be
free from bias. The result, in this case, is dramatic. Even allowing some
manipulation, the substantial gap between the fossil fuels <strong>and</strong> their
renewable alternatives would require excessive “cooking” to close.
A key take-away from this chapter is that we can devise methods to
compare disparate sources of energy in a systematic way. The outcome
does not provide an authoritative answer, but what it can do is:
◮ help guide our thinking;
◮ expose gaps that we might not otherwise appreciate;
◮ bring attention to the complexity of energy choices: it’s more than
how many terawatts are available.
One lesson is that a transition away from fossil fuels does not appear at this
time to involve superior substitutes, as has been characteristic of our energy
history. The alternatives might be good enough,evenifnotas good as what
we are accustomed to using. Fossil fuels represent a generous one-time
gift from the earth. From our current vantage point, it is not clear that
energy—vital to our economic activity—will be as cheap, convenient,
<strong>and</strong> abundant as it has been during our meteoric ascent to the present.
If not for finite supply <strong>and</strong> the CO 2 problem, fossil fuels would continue
to satisfy our energy needs—shifting focus to various other global-scale
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.