Energy and Human Ambitions on a Finite Planet, 2021a

2 Economic Growth Limits 28
Just because we can point to some completely legitimate examples of
decoupled activities <strong>and</strong> many impressive substitution stories does
not mean that an entire economy can be based on indefinite continuance
of such things. We are physical beings in a physical world <strong>and</strong>
have non-negotiable minimum requirements for life. The activities <strong>and</strong>
commodities that support critical functions cannot continue to exp<strong>and</strong>
indefinitely, <strong>and</strong> will not become arbitrarily cheap once their expansion
hits physical limits. The finite nature of our world guarantees that such
limits will be asserted, committing economic growth to stall in turn.
Nothing, in the end, escapes physics.
So, while acknowledging that growth in the past has brought uncountable
benefits to the human endeavor, we have to ask ourselves: If the
end of growth is inevitable, why does it remain our prevailing plan?
2.6 Problems
1. At a 3.5% growth (interest) rate, how much would $1,000 invested
at the time Columbus sailed to America be worth today (hint: use
the rule of 70)? Put this in context (compare to richest individuals
or find a similar GDP for some country).
i Retention of Chapter 1 material is assumed.
The real world is not partitioned
into chapters, <strong>and</strong> neither should your brain
be.
2. As an indication of how sensitive the accumulation is to interest
rate, compare the result from Problem 1 to what would happen
for interest rates of 4% <strong>and</strong> 5%—again putting into context.
3. Find the energy intensity for at least four countries spanning a
range of development levels. For each country, look up the GDP,
<strong>and</strong> find energy consumption at: Wikipedia page on Primary <strong>Energy</strong>
Consumption.[13] In order to compare to Figure 2.2, multiply
the number in quadrillion Btu (qBtu) by1.055 × 10 18 J/qBtu. Also
note that a trillion is 10 12 .
4. Estimate the energy intensity of the UCSD campus, based on an
annual electricity expenditure around 10 15 J. 26 For the financial
side, assume that student payments (tuition, fees, room <strong>and</strong> board)
accounts for 40% of the total budget. 27 Use your knowledge of
typical tuition/fees <strong>and</strong> enrollment to come up with a number.
Compare your result to global figures for energy intensity.
Look at the column for total energy consumption
in units of quadrillion Btu.
26: Based on a 30 MW electrical load times
the number of seconds in a year; this won’t
account for all energy expenditures, missing
transportation, for instance.
27: Federal grants comprise most of the
rest, <strong>and</strong> a small amount from state taxes
Don’t get hung up on in-state fraction; just
make a crude guess (maybe guess an average)
<strong>and</strong> clearly state assumptions.
5. Typical energy costs are in the neighborhood of $0.10 per kilowatthour
(kWh), <strong>and</strong> 1 kWh is 3.6 MJ (megajoules). Take the ratio of energy intensity for all economic activities
The result should be larger than the typical
these two figures to form an economic energy intensity of energy within a country, since not all monetary
expenditure goes toward energy.
itself, in units of MJ/$.
6. If a country clocks in at 5 MJ/$ for its overall energy intensity,
<strong>and</strong> its energy costs work out to an energy intensity of 30 MJ/$, 28
what percentage of the economy do we infer constitutes the energy
sector?
28: In the same sense as was calculated for
Problem 5
The answer should be well less than 100%.
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.