Environmental Engineering Reference
In-Depth Information
only practical means of storing large quanta of almost
instantly deployable energy. In spite of more than a cen-
tury of diligent efforts to develop other effective storages,
all other options remain either inefficient or inadequate
(fig. 13.9). Opportunities for building large pumped
storages are limited. By 2005 there were only two large
compressed air energy storage facilities (290-MW Hun-
torf in Germany and 110-MW McIntosh in Alabama),
but several larger projects were in development (Van der
Linden 2006). Capacities of flow batteries (typically up
to 15 MW), flywheels (containerized 1-MW systems),
and superconducting magnetic energy storage (average
rating 3 MW) remain limited.
Agricultural adjustments in fully solar societies would
be equally profound. Intensive field cropping is a space
reduction technique made possible by rising energy sub-
sidies in order to support increasing population densities.
In 1900 the nonsolar subsidies in global agriculture
added to about 100 PJ, and they helped to produce har-
vests of about 6 EJ. A century later the subsidies rose to
at least 13 EJ, and the output reached about 35 EJ. A
purely solar society would have to replace all crude oil-
based liquid fuels needed for fieldwork and irrigation,
and it would face an additional challenge of using renew-
ably generated electricity to decompose water in order to
get hydrogen for ammonia synthesis (the element now
comes from natural gas). On the other hand, advanced
(and impossible to predict) genetic modification could
become a powerful factor in reducing energy inputs.
And in the long run it may be even possible to engineer
photosynthetic systems for direct production of hydro-
gen (Smith, Friedman, and Venter 2003), but for neither
of these possibilities are there any time and scale specifics.
There are no decision-making shortcuts to aid in
selecting and optimizing strategies leading in the right
direction. The ultimate makeup of a new global energy
system that may dominate in the second half of the
twenty-first century will not resemble currently fashion-
able scenarios. Moreover, prevailing energy pricing does
not send the correct signals for the needed change.
There is no doubt that energy prices have ignored (or at
best only partially internalized) many environmental,
health, and strategic externalities, but it is not clear that
economic honesty will push us inexorably toward renew-
able energy (Mintzer, Miller, and Serchuk 1995). Calcu-
lating the real cost of energy is a complex challenge that
may yield only an unhelpful, too broad range of out-
comes rather than a single convincing value.
Careful process energy analyses are a valuable manage-
ment tool, but thermodynamic efficiency should not
become the overriding arbiter in social decisions. Our
monetary valuations are very unsatisfactory on many
scores, but substituting energy valuations would merely
install another misleading denominator. Calculations of
net energy returns are desirable (although not necessarily
decisive) in assessing the costs of energy supply, but they
are irrelevant when they ignore qualitative considerations
and nonenergy benefits, for example, food eaten for its
protein, vitamins, and minerals or for its taste or cachet,
or electricity chosen for its cleanliness, adjustable control,
and versatility.
I strongly believe that the key to managing future
global energy needs is to break with the current expecta-
tion of unrestrained energy use in affluent societies. Of
course, Ethiopia or China needs more energy services
and hence an efficiently expanded supply. But most of
the world's low-entropy flux is used by nations that could
derive great benefits from seriously examining their
longstanding pursuit of higher energy inputs. At the be-
ginning of the twentieth century Ostwald tied the avail-
