While there is plenty of reasons for concern over biofuels, there are also many benefits that have not been fully appreciated in large part because the biomass sources we work with are not optimized for biofuel production.  The plants we use are largely designed for the production of a food or fiber commodity, and have been bred for these products over many thousands of years.  In the case of maize, for example, we see multiple analysis of the cost-benefit ratios for the production of grain ethanol.  The use of grain is not ideal, because most of the potential biomass is left in the field after harvest.  Other crops such as switchgrass, poplar and Miscanthus have also become the focus of attention.  These are better in that all of the aboveground biomass is used, but they do not produce much fermentable sugars or oils for biodiesel fuel.  Hence, there is much talk of developing complex methodologies to break cellulose and lignins into liquid fuels. 

Rather than pushing forward with less than optimal solutions for the biofuel problem, we need to step back and consider what are the ideal characteristics of a biofuel crop, and what do we need to do to create ideal biofuel crops from the genetic sources that now exist.  Certain species could probably be easily modified by breeding or genetic engineering.  For example, sugar cane is a C4 crop with high radiation use efficiency, but cannot tolerate chilling; hence it is impractical for temperate zones were most of the agricultural land occurs. There are high elevation species of sugar cane, and a related species, Miscanthus giganteus, is cold tolerant and is one of the more prominent biofuel candidates.  Breeding a cold-tolerant sugar cane for temperate zones could completely alter the biofuel discussion. Alternatively, one could engineer a Miscanthus that stores high amounts sugar, as sugar cane does.  There are also many wild species we might develop for biofuels.  In central Asia, there are a number of C4 shrubs such as Black Saxual (Haloxylon aphyllum) that have been used locally for fuel for centuries.  These can survive harsh, saline and arid conditions, and thus could produce a commodity on much of the degraded rangelands of the world. There are also numerous C4 Euphorbia species that produce hydrocarbons that can easily be harvested for biodiesel, but none are under active consideration.  One additional possibility is that biofuels are the only viable option to actively reduce greenhouse gas levels in the atmosphere.  If we burn biomass in a power plant and capture the CO2 emission for burial, we are effectively pumping CO2 out of the air and back into the ground.  This capacity to reduce CO2 could greatly improve biofuel economics if carbon trading schemes become widely accepted.

As these examples show, there are many ways to improve the economics and yield of biofuels.  We have only begun to consider the possibilities.  Unfortunately, much of the debate now focuses on the efficacy and risks of current crops, rather than the potential of future crops that are engineered for optimal fuel output while reducing environmental risks.  Biofuels do pose severe risks to the environment if managed carelessly, but they also have the potential to reduce greenhouse gas levels, produce local sources of energy, and restore rural economies.  Biofuels will not be able to replace fossil fuels in the future; however, with climate warming, and the cost increases in fossil fuels, biofuels will have to become a significant part of the long term energy outlook for the planet. 

I imagine if we could properly factor in the true cost of fossil fuel use (in other words, include the long-term costs of climate change), then biofuels would be economically viable in today’s markets, and this could spur rapid innovation and product optimization.