Energy and Human Ambitions on a Finite Planet, 2021a

17 Comparison of Alternatives 302
5. Why is it so hard to satisfy transportation needs? What is it about
fossil fuels that has made transportation so much easier than
electrified transport would be?
6. Verify—showing work—the claim on page 292 that a car refueling
at a gasoline station is transferring energy at a rate in the neighborhood
of 15 MW if the transfer rate is about 6 gallons (23 L) per
minute 32 <strong>and</strong> gasoline contains about 34 MJ per liter.
32: Time it yourself some time.
7. What is at about the backyard 33 attribute that earns so many red 33: . . . just shorth<strong>and</strong> for energy on a personal
scores? What does this tell you about access to energy <strong>and</strong> the
scale at home
complexity of its capture/use?
8. What two resources are crippled by intermittency? How might
that challenge be mitigated so that it is less problematic? What are
some difficulties in this solution?
9. If biofuels turn out to be hampered by low EROEI values, the
only transportation-friendly option left is artificial photosynthesis,
which was not covered in this book because it’s not a “real thing”
at this time—as captured by the two red squares for difficulty <strong>and</strong>
demonstrated. Two questions:
a) What other resources are in a similar “not real yet” state,
based on the same red squares?
b) What is most encouraging about the prospect of obtaining
liquid fuels from sunlight? What problems does it solve for
solar power <strong>and</strong> for transportation?
10. Figure 17.2 left out firewood as an energy resource, even though
it has been with us for a long time <strong>and</strong> will no doubt continue to
provide home heating. What would the ten colors be for this resource
of intermediate abundance in the context of home heating?
What would its score be, <strong>and</strong> which sources is it then tied with?
Justify each of your color choices.
11. (Suggest triple-credit problem) For the sake of simplicity <strong>and</strong>
transparency, the scoring system used a simple uniform weighting
for each of the 10 attributes, but it is unlikely all ten are equally
important. Make up your own weighting scheme. 34 For each energy
resource, blue cells add the corresponding category’s weight, <strong>and</strong>
red subtracts, <strong>and</strong> yellow does nothing. Re-score the matrix using
your own weights—including the fossil fuels. Now re-order the
matrix from highest to lowest score <strong>and</strong> comment on any major
upheaval from the nominal ordering. What are the big surprises?
Did the fossil fuel gap persist?
Different students may get different
results, but this will provide some appreciation
for considerations that enter the creation
of such a scoring scheme.
34: A category might be worth 2 points,
0.3 points, 5 points, or whatever you wish;
need not add to 10
First, make sure you can reproduce the scoring
in the present table based on all weights
being 1.0.
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.