Reducing Carbon Intensity of Food and Fuel Production Whilst Lowering Land-Use Impacts of Biofuels

Abstract

Science and technology are critical for developing novel and sustainable production of food, fuel, and chemicals in a manner that significantly reduces anthropogenic contributions to climate change. Although renewable energy is gradually displacing fossil fuels for grid energy, oil-based transport fuels remain major contributors to global greenhouse gas emissions. Currently, bioethanol and biodiesel can partially replace petroleum, but these renewables are far from perfect in terms of long-term sustainability and the volumetric expansion needed to fully replace oil. Biofuels made in biorefineries using sugars or oils derived from plants grown on prime food-producing land only partly offset CO2 emissions relative to petroleum and present problems with respect to land-use change. Here, we provide alternative ideas for lignocellulosic biorefineries that coproduce bioethanol, nutritious protein-rich yeast biomass for animal feeds, and carbon-rich solid residuals that represent green coal or sequestered carbon. A concept of how these biorefineries could be linked to renewable power-to-X, where X can be bioethanol, protein, sequestered carbon, or multiple carbon-carbon based synthetic fuels and chemicals, is presented. We also discuss aspects of the present and future roles for microorganisms in lignocellulosic biorefineries and power-to-X bio/chemical refineries.