New trends in physics teaching, v.4; The ... - unesdoc - Unesco

New Trends in Physics Teaching IV
consumption of these resources endlessly into the future. Furthermore, one must recognize that
the energy cost of producing a unit of fossil fuel energy increases as the reserves are depleted. So
the net energy represented by a tonne of coal or of crude oil will generally decline into the future.
Thus even if the fossil fuel were produced in the future ‘at present rates’, the net energy available
to society from this production would decline. As noted by Odum [ 131 : ‘Scenarios based on
gross reserves overestimate the time the reserves wil last. Scenarios should be based on net
energy, that is energy yield minus that needed to collect and process the energy.’
It is vital that we point out this ‘Most Common Misrepresentation’ to our students so that they
can recognize it and can appreciate that the misrepresentation gives life expectancies which are
longer (often by an order of magnitude) than the Exponential Expiry Times calculated for
reasonable current and anticipated rates of growth of production. We must also point out the
importance of the concept of net energy in estimating the lifetime of fossil fuel reserves.
Our students must recognize that, in response to legitimate technical questions, we wil be
given answers which sound impressive but which, on close examination, are seen to bear no
relation at all to the question. This is well illustrated in a discussion in US. News and World
Report (13 August, 1979, p.35):
However gasohol has many critics who focus on its hgh costs and claim that it results in a net loss of energy.
‘You’re making alcohol that generates less energy when burned than it took to make it’ argues a distillery official.
Advocates respond that the price gap between gasoline and gasohol narrows with each increase in oil prices; mass
production of alcohol wil make it even cheaper, they contend.
Note that the ‘answer’ bears no relation to the question.
WHAT DO WE DO NOW?
The problems are such that we have rather few options. All of the following points are vital:
(i) We must educate all of our people to an understanding of the arithmetic and consequences
of growth, especially in terms of population and in terms of the earth’s finite resources. David
Brower [ 141 has observed that ‘the promotion of growth is simply a sophisticated way to steal
from our children.’
(ii) We must educate people to the critical urgency of abandoning our almost religious
belief in the disastrous dogma that ‘growth is good’, that ‘bigger is better’, that ‘we must grow
or we will stagnate’, etc. We must realize that growth is but an adolescent phase of life which
stops when physical maturity is reached. If growth continues in the period of maturity, it is
called obesity or cancer. Prescribing growth as the cure for the energy crisis has all the logic of
prescribing increasing quantities of food as a remedy for obesity.
(iii) We must economize in the use and consumption of everything. We must recognize that, as
important as it is to economize, the arithmetic shows clearly that large savings from that action
wil be wiped out in short times by even modest rates of growth. For example, in a dozen or so
years a massive federal programme might result in one half of the heat for the buildings where we
live and work being supplied by solar energy instead of by fossil fuels. This would save 10 per
cent of our national use of fossil fuels, but this enormous saving could be completely wiped out
by two years of 5 per cent growth! Conservation alone cannot do the job! The most effective
way to conserve is to stop the growth in consumption.
(iv) We must re-cycle almost everything. Except for the continuous input of sunlight, the
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