Biofuels are confusing because they’re complicated, and they’re complicated mainly because of indirect effects. It’s similar to the unintended consequences of hydropower stopping salmon from spawning upstream, or windmills killing birds … except way more complicated. Biofuels almost always affect how land is used around the world. The basic theory is that any carbon combusted into the atmosphere from biofuels was first sequestered by plant growth, so there’s no net change in atmospheric carbon. But that only makes sense if someone is growing plants in an abandoned parking lot. It takes a lot of land to grow biofuel feedstock, and that land is either (a) newly converted from forest or grassland, or (b) already used to grow crops for food. In scenario (a), direct land use change by cutting down forest or digging up grassland releases a lot of CO2 from biomass and soil, and harms wildlife. In scenario (b), diverting food to biofuel drives up the price of food and leads to indirect land change by someone cutting down forest or digging up grassland to plant more food somewhere else in the world. In energy generation, as in everything else, it’s hard to get something for free.