Energy and Human Ambitions on a Finite Planet, 2021a

13 Solar <strong>Energy</strong> 221
In terms of implementation, solar thermal is a small player. In 2018, only
four states produced solar thermal power, 68% from California <strong>and</strong> 22%
from Arizona. Table 13.4 provides some context, comparing ST to PV in
each of the four states that have any solar thermal. For the entire U.S.,
less than 0.1% of electricity derives from solar thermal, <strong>and</strong> PV is about
25 times bigger on the whole. Globally, ST averages about 1.1 GW 93 93: . . . 0.006% of global dem<strong>and</strong>
(2016), about half in Spain <strong>and</strong> a third in the U.S. 94 94: ...therefore not much left in the rest of
the world
State ST MW avg. ST % elec. PV MW avg. PV % elec. ST/PV %
California 281 1.25 4,285 19.0 6.6
Arizona 89 0.08 765 5.1 11.6
Nevada 35 0.09 552 12.1 6.3
Florida 6 0.002 326 1.2 1.8
U.S. total 410 0.086 10,565 2.2 3.9
Table 13.4: Solar Thermal (ST) generation in
the U.S. in 2018, compared to photovoltaic
(PV); MW is megawatts.
13.8.3 Pros <strong>and</strong> Cons of Solar Thermal
Summarizing the pros <strong>and</strong> cons for solar thermal (ST), starting with the
good aspects:
◮ ST taps into a super-abundant resource—the only renewable that
has such a margin;
◮ ST technology is low-tech <strong>and</strong> inexpensive, using well-developed
power plant technologies;
◮ ST has built-in short-term storage capacity for covering evening
power dem<strong>and</strong>s;
◮ Life-cycle CO 2 emissions are 20 times smaller than that of traditional
fossil fuel electricity [68].
[68]: (2020), Life Cycle GHG Emissions
And the less great stuff:
◮ ST requires direct sunlight; intolerant of clouds;
◮ ST is only possible at utility-scale, requiring a power plant;
◮ ST has a lower l<strong>and</strong>-area efficiency than PV panels;
◮ Some disruption will be imposed on the local environment/habitat.
13.9 Upshot for Solar
H<strong>and</strong>s down, solar is the only renewable resource capable of matching
our current societal energy dem<strong>and</strong>. Not only can it reach 18 TW, it can
exceed the mark by orders of magnitude. Finding space for panels is not
a limitation. The efficiency of PV panels is perfectly respectable based
on physics expectations, <strong>and</strong> beats the best that biology has done by a
factor of 3–4. The efficiency is high enough that roof space tends to be
more than sufficient to satisfy the dem<strong>and</strong>s of individual houses.
Pros <strong>and</strong> cons are listed separately for PV
<strong>and</strong> ST in Section 13.7.1 <strong>and</strong> Section 13.8.3,
respectively.
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.