A vicious cycle, right? But researchers write that cellulosic biofuels may provide promise for energy independence. These new biofuels could be designed to coproduce animal feeds and recover and recycle mineral nutrients.
Additionally, they make the case that crop and forage residues used for cellulosic biofuel production can be harvested without requiring more land. Further, they estimate that annually, at least 1.5 billion tonnes of residues are already available worldwide.
Inevitably, the age-old food vs. fuel debate appears. But the authors say second-generation fuels – like cellulosic fuels – are much less likely to impact food prices because production of the fuels can be integrated with production of animal feeds and enhanced by growing and harvesting double or cover crops.
"Resolving the apparent 'food versus fuel' conflict seems to be more a matter of making the right choices rather than hard resource and technical constraints," the authors say.
They propose that one of those 'choices' could be to recover plant nutrients, such as N, P and K, by burning fermentation residue from biofuel production and spreading the concentrated ash on land.
Nutrients not to be left behind
Though the food versus fuel debate may have a light at the end of the tunnel, CAST researchers were quick to point out that nutrients in the soil – those responsible for nourishing the cover crops, cellulosic feedstocks and grain crops needed to produce more food or consume directly – are a key part of harvesting top yields.