“Because of the low photosynthetic efficiency and the competition of energy plants with food plants for agricultural land, we should not grow plants for biofuel production. The growth of such energy plants will undoubtedly lead to an increase in food prices, which will predominantly hit poorer people.” ~Dr. Hartmut Michel
That’s the conclusion of someone who should know: Nobel-winning photosynthesis expert Hartmut Michel, currently the director of the Molecular Membrane Biology department at the Max Planck Institute for Biophysics.
The math just doesn’t add up. The problem is two-fold: First, plants only convert around 1% of the sun’s energy into chemical energy. But then we have to harvest all these low-energy plants and try to convert them into a fuel we can burn in our cars—an even less efficient process. Treehugger.com quotes Dr. Michel:
When the yields of biofuels per hectare are known, one can easily calculate how much of the energy of the sunlight is stored in the biofuels. For German “biodiesel” which is based on rapeseed, it is less than 0.1%, for bioethanol less than 0.2%, and for biogas around 0.3%. However, these values even do not take into account that more than 50% of the energy stored in the biofuel had to be invested in order to obtain the biomass (for producing fertilizers and pesticides, for ploughing the fields, for transport) and the chemical conversion into the respective biofuel. This energy normally is derived from fossil fuels.
The bottom line is that it takes a huge amount of land to grow these plants, and a great deal of energy to harvest and concentrate the small amounts of energy collected per plant into something that can actually power our vehicles, which are still quite heavy and inefficient themselves. All that land could be growing food, and indeed, would provide far more food than vehicle fuel. A lot of food or very little fuel? It doesn’t take a Ph.D. to do the math…
“The future of our individual transport has to be electric!” ~ Dr. Hartmut Michel