Energy and Human Ambitions on a Finite Planet, 2021a

17 Comparison of Alternatives 295
Hydroelectric (Chapter 11): Despite impressive efficiency, hydroelectric
potential is already well developed in the world <strong>and</strong> is destined to
remain a sub-dominant player on the scale of today’s energy use. It has
seasonal intermittency, 15 does not directly provide heat or transport,
<strong>and</strong> can only rarely be implemented on a personal scale. Acceptance
is fairly high, although silting <strong>and</strong> associated dangers—together with
habitat destruction <strong>and</strong> the forced displacement of people—do cause
some opposition to expansion <strong>and</strong> have resulted in removal of some
hydroelectric facilities.
Biofuels from Algae (Sec. 14.3.2; p. 234): Because algae capture solar
energy—even at less than 5% efficiency—the potential energy scale is
enormous. 16 Challenges include keeping the plumbing clean, possible
infection, 17 contamination by other species, <strong>and</strong> so on. At present, no algal
sample that secretes the desired fuels has been identified or engineered.
No one knows whether genetic engineering will succeed at creating a
suitable organism. Otherwise, the ability to provide transportation fuel
is the big draw. Heat may also be efficiently produced, but electricity
production would represent a misallocation of precious liquid fuel.
15: A typical hydroelectric plant delivers
only 40% of its design capacity.
16: However, low EROEI may make the
enterprise non-viable.
17: ...forexample, a genetic arms race with
evolving biological phages
Geothermal Electricity (Sec. 16.1; p. 275): This option makes sense
primarily at rare geological hotspots. It will not scale to be a significant
part of our entire energy mix. Aside from this, it is relatively easy, steady,
<strong>and</strong> well demonstrated in many locations. It can provide electricity, <strong>and</strong>
obviously direct heat—although often far from locations dem<strong>and</strong>ing
heat.
Wind (Chapter 12): Wind is neither super-abundant nor scarce, being
one of those options that can meet a considerable fraction of present
needs under large-scale development [70]. Implementation is relatively
straightforward, reasonably efficient, <strong>and</strong> demonstrated the world over in
large wind farms. The biggest downside is intermittency. It is not unusual
to have little or no regional input for several days in a row. Objections to
wind tend to be more serious than for many other alternatives. Wind
turbines are noisy <strong>and</strong> tend to be located in prominent places (ridgetops,
coastlines) where their high degree of visibility alters scenery. Wind
remains viable for small-scale personal use.
Artificial Photosynthesis: Combining the abundance of direct solar input
with the self-storing flexibility of liquid fuel, artificial photosynthesis
is a compelling future possibility [113]. Being able to store the resulting
liquid fuel for many months means that intermittency is eliminated to
the extent that annual production meets dem<strong>and</strong>. A panel in sunlight
dripping liquid fuel could satisfy both heating <strong>and</strong> transportation needs.
Electricity can also be produced, but given an abundance of ways to
make electricity, the liquid fuels would be misallocated if used in this
way. Unfortunately, an adequate form of artificial photosynthesis has
yet to be demonstrated in the laboratory, although the U.S. Department
of <strong>Energy</strong> initiated a large program in 2010 toward this goal.
[70]: Castro et al. (2011), “Global Wind Power
Potential: Physical <strong>and</strong> Technological Limits”
[113]: Andreiadis et al. (2011), “Artificial Photosynthesis:
From Molecular Catalysts for
Light-driven Water Splitting to Photoelectrochemical
Cells”
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.