Lots of people are getting excited about all the various technologies for using biofuels as a replacement for fossil fuels. Plant-based fuel may present a short-term option. But looking at the different kinds of energy production that are possible gives some insight into the best directions to promote in terms of long-term efficient energy production.

A study cited on EV World compares different crop- and direct-production methods of generating energy in terms of miles per acre per year. This gives some eye-opening information.

At the bottom end of the scale is soybean biodiesel, which can provide only 2,400 miles per acre per year. Corn ethanol is more than six times as efficient, yielding 18,000 miles per acre per year. But because of the relatively slow rate of production from plant-based fuels, these options fall far below the productivity of directly produced energy.

The same acre can produce 10 times as much energy from wind as it can from corn ethanol -- 180,000 miles per acre per year. But both corn ethanol and wind power pale in comparison with solar photovoltaic power, which can produce more than 2 million miles worth of transport per acre per year.

This is not to completely dismiss biofuels. The cost of an acre's worth of solar PV arrays is more than 100 times more expensive than planting an acre of corn. Many biofuels can be produced on marginal lands that are ill-suited for solar. And cellulosic ethanol can even be produced from waste, effectively making it a zero land-use fuel.

Presumably the comparisons are based on sites that are optimal for each mode of generation. A site that is highly suitable for harvesting wind energy may not be a good site for growing corn, and vice versa.

The infrastructure and the existing "car parc" (the entire fleet of all vehicles in the country) is also going to take decades to turn over to the point where a significant proportion of the vehicles on the road are electric vehicles.

Both a mix of energy sources and regionally appropriate choices need to be part of a comprehensive energy plan. But this offers a useful comparison that suggests where the best allocation of resources should be focused in terms of long-range planning for our energy future.

Link: EV World (chart halfway down the page)