Energy and Human Ambitions on a Finite Planet, 2021a

17 Comparison of Alternatives 294
<strong>and</strong> these are precisely what our populated planet strains the most.
17.2 Tally for Individual Alternative Sources
A single chapter cannot adequately detail the myriad complex considerations
that went into the matrix in Figure 17.2. The previous chapters
address a number of the considerations, but many of the quantitative
<strong>and</strong> qualitative aspects for each were developed at the Do the Math
website. The key qualities of each resource in relation to the matrix
criteria are discussed in this section, focusing especially on less obvious
characteristics.
Solar PV (Sec. 13.3; p. 201): Covering just 0.4% of Earth’s l<strong>and</strong> area with
PV panels that are 15% efficient satisfies global annual energy dem<strong>and</strong>,
qualifying solar PV as abundant. PV panels are being produced globally
in excess of 100 gigawatts (GW) peak capacity per year, 13 demonstrating
a low degree of difficulty. Most people do not object to solar PV on
rooftops or over parking areas, or even in open spaces. 14 Solar panels
are well suited to individual operation <strong>and</strong> maintenance. Intermittency
is the Achilles’ heel of solar PV, requiring storage solutions if adopted
on a large scale. To illustrate the difficulty of storage, a lead-acid battery
large enough to provide the United States with adequate backup power
would require more lead than is estimated to be accessible in the world
<strong>and</strong> would cost approximately $60 trillion at today’s price of lead [112].
Lithium or nickel-based batteries fare no better on cost or abundance.
Pumped storage is limited by a small number of suitable locales.
13: . . . translating to about 10–15 GW of average
power production added per year
14: . . . especially sun-saturated deserts
[112]: Pickard (2012), “A Nation-Sized Battery?”
Solar Thermal (Sec. 13.8.2; p. 219): Achieving comparable efficiency
to PV but using more l<strong>and</strong> area, the process of generating electricity
from concentrated solar thermal energy has no problem qualifying
as abundant—although somewhat more regionally constrained. It is
relatively low-tech: shiny curved mirrors, tracking on (often) one axis,
heat up oil or a similar fluid to drive a st<strong>and</strong>ard heat engine. Intermittency
can be mitigated by storing thermal energy, perhaps even for a few days.
A number of plants are already in operation, producing cost-competitive
electricity. Public acceptance is no worse than for PV, but the technology
generally must be implemented in large, centralized facilities.
Solar Heating (Sec. 13.8.1; p. 218): On a smaller scale, heat collected
directly from the sun can provide domestic hot water <strong>and</strong> home heating.
In the latter case, this can be as simple as a south-facing window. Capturing
<strong>and</strong> using solar heat effectively is not particularly difficult, coming
down to plumbing, insulation, <strong>and</strong> ventilation control. Technically, solar
heating potential might be abundant, but since it is usually restricted to
building footprints (roof, windows), it gets a yellow rating. Solar heating
does not lend itself to electricity generation or transport, but it has no
difficulty being accepted <strong>and</strong> almost by definition is a backyard-ready
technology.
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.