Saturday, June 26, 2010

Energy efficiency

We are constantly told that improving energy efficiency is the key to an effective energy policy, but the truth is that it is an essentially meaningless goal. The direct cost and the indirect (environmental, societal, etc.) costs vary greatly between energy sources, so the importance of efficiency also varies. There may be good reasons to reduce use of coal (air pollution) or oil (oil imports) – but if we can supply energy at low cost and with little environmental impact (space-based solar power comes close), why should we care how much of it people use? 

The solar radiation falling on the Earth is 10,000 times greater than the total energy used by humans. If the Earth were a black body, our current energy use would increase the temperature by 0.007 deg C – but in fact there are feedback mechanisms that stabilize the temperature, so the real temperature rise is much less than this. We have a long way to go before we need worry about direct planetary heating from energy use.

The claim that we must reduce use of all kinds of energy stems from the environik fantasy of a future in which we all live frugally in modest, wind-powered cottages among the trees, cultivating our little organic gardens, using only small-scale technology, and celebrating our solidarity with all creatures, great and small. This pastoral idyll cannot happen, because this kind of agriculture cannot support the present or future world population, and because a hand-ax or a screwdriver implies the existence of Pittsburgh. These idiots dream of a kind of worldwide Vermont, but the reality would be more like a slum in Bangladesh.

The annual global consumption of marketed energy has increased by a factor of 25 since 1900, and now stands at 500 quads (1 Q = 10^15 BTU = 2.93 X 10^11 kWh). Although energy intensity (energy used per dollar of GDP) has been decreasing everywhere, the world will need at least 3000 Q/year by the end of this century.

Energy policy MUST be directed to finding within a few decades ways to generate an order of magnitude more energy than the human race uses now, at affordable cost and with minimal environmental impact.

In the longer term, we may need thousands of times more energy. The next post offers an example.

I don't object to improving energy efficiency if in a particular instance it saves money or reduces environmental, impact, but it is a trivial distraction from the real problem of supplying energy.

1 comment:

Jim Talt said...

So where'd you go...! I'm waiting for that next post you promised herein. BTW, I laughted at your comment "hand-ax or a screwdriver implies the existence of Pittsburgh." Then I realized that I had finally caught you in an error! Rather than Pittsburgh, it implies the existence of some unpronouncable province in China.