Maybe it is this convenience that has created such a strong bias towards considering biofuels a carbon-free source. Almost all policymakers currently do so. The problem is that it's not true, and a double counting error made in almost all policy calculations overestimates the impact that biofuels use will have on carbon emissions.2 Here's why.
All plants and trees act as a huge carbon sink to take in CO2 from the atmosphere through photosynthesis - without this sink, our planet would be much hotter than it already is. Burning biofuel for energy use does release CO2, but policymakers argue that this is balanced by the regrowth of the new biomass used for future biofuel production. The exact amount of CO2 emitted by burning biofuels is reabsorbed by the crops being grown for the sole purpose of biofuel production.
At first glance, this argument looks great, but the problem lies in a hidden assumption that the land used to grow biomass for biofuels would not have already been a carbon sink before it was used for biofuel production.2 Actually, biomass for biofuels would be grown on arable land on which trees, grass, prairies, etc. are already growing, happily absorbing CO2 and helping to reduce the pace of global warming. This carbon sink would have to be removed to grow the biomass for biofuels, which essentially creates a net gain of zero in terms of carbon sink size. When the biofuel is later burned as fuel, this would emit CO2 to the atmosphere, contributing to greenhouse gas emissions and global warming in the same way as fossil fuels. The double counting comes from incorrectly counting the carbon sink from the natural woodlands already in existence on top of the carbon sink from the grown biomass (read Reference 2 below for more details on this argument - it's not intuitive at first but well worth thinking about!).
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