Peak what?

We've already seen peak US oil, and peak NA natural gas.  We may already have seen peak oil for the world, or it may hold off until turkey day.  But I keep seeing people who insist on using the term "peak energy" for this.

This term is misleading.  It's true that we don't have other resources ready to pick up where oil and natural gas are leaving off.  This is to be expected; oil and gas have been so cheap that it made little sense (greenhouse emissions and other pollution aside) to create a parallel infrastructure to substitute for them.

Right now we are getting toward the tipping point.  The production of crude oil either peaked last year, is about to peak (perhaps on Thanksgiving) or will peak by 2010; it depends whose crystal ball you consult.  Even US gasoline prices are getting high enough to move consumer demand from the large SUV segment (50% decline over 2004) to hybrids.  Does that mean this peak energy?

Oil only accounts for about 160 quads out of humanity's 400 quad/year energy consumption.  The remainder comes from natural gas, coal, biomass, hydropower, nuclear and the like.  At least two of those have substantial room for growth in world production in the relatively near future; extrapolating "peak oil" to "peak energy" is unwarranted.

On the other hand, transportation is still closely wedded to oil.  Does that mean we're about to see "peak miles" and a slow collapse of the economy as jobs and homes must be abandoned due to unaffordability?

Not on your life.  One of the biggest complaints about the US vehicle fleet is its inefficiency!  A replacement of the American vehicle fleet (~22 MPG average) with Prius-class vehicles (46 MPG highway, possibly greater city) would deliver the same miles from roughly half the amount of fuel.

We are already seeing some movement in this direction.  Over just a few months, many drivers have changed their vehicle of choice from a large SUV to a small SUV or even an economy car.  People drove slower.  For a given number of miles travelled, less fuel was needed.  These adaptations can only go so far, but they show that it is both possible to cut fuel consumption and that people will act to do it.

Suppose that a 50% improvement in fuel economy reduction in fuel consumption is the best we can do.  When we're all driving things as good as the Prius and oil falls to half its current production, THEN are we in trouble?

Not if we play our cards right.  The plug-in hybrid is coming; electric propulsion is already good enough to be offering 85% reductions in motor-fuel needs.  But that's not the end.  Radically improved batteries have been announced by several different companies, offering huge increases in power/weight (5 kW/kg), charge/discharge rate (100 C), and lifespan.  The inevitable outcome of these advances is an all-electric car which can go several hundred miles at highway speeds and recharges in 5 minutes.  Long before that, the same batteries will make hybrids more muscular than all but the most exotic sports cars.  The same advanced 5 kWH battery which could drive a Prius+ for 20 miles or so could also deliver enough power (500 kW!) to leave Corvettes in the dust.  If you're imagining a Miata with the power of a NASCAR racer, you've got the right idea.

The energy to run these cars will not be hard to come by.  The US auto fleet burned roughly 139 billion gallons of gasoline last year.  At an average efficiency of 17%, this amounts to 99.7 GW actually delivered to the wheels, or 873 billion kWh per year.  The wind in Texas alone could produce 386 billion kWh per year, or 44% of the total.  Efficiency of the electric vehicles will be higher, but losses will cut the available energy by perhaps 30%; regardless, the available energy is more than sufficient to meet our needs.

The available wind power world-wide has recently been calculated as 72 terawatts.  That's more than 5 times what humanity currently uses from all sources, and enough to give 8 kW to each of 9 billion people.

I haven't even touched on solar yet.  Humans use about 400 quadrillion BTU (quads) of energy per year from all sources; the Sun delivers this much energy to Earth in about 41 minutes.  Developments in the pipeline might increase the efficiency of PV cells from 15% to 60%, roughly 30 times as great as the most efficient higher plants.  Such cells would produce an explosion in energy availability and thus energy use, without pollution.

So:  Will we see "peak energy" in this decade, or even in this century?  We may well see a local maximum in the raw consumption curve and some slide in useful output, but as for absolutes in either.... not any time soon.

¶ 11/15/2005 11:17:00 AM