The shift from fossil fuels to renewable energy is occurring mainly at the power plant level. But what about transportation? Can we significantly reduce greenhouse gas emissions by switching to cleaner fuels? Or is this just an attempt to keep 20th century technology chugging along while trading one set of environmental problems for another?
Biofuels aren’t new and they aren’t used solely for transportation. Power plants can burn wood, for example, and many of the first autos, including Ford’s Model T, ran on ethanol or peanut oil. But they’re now seen as an alternative to fossil fuels for transportation.
Biofuels offer several advantages over fossil fuels. Most are less toxic. Crops used to produce them can be grown quickly, so unlike coal, oil, and gas that take millions of years to form, they’re considered renewable. They can also be grown almost anywhere, reducing the need for infrastructure like pipelines and oil tankers and, in many areas, conflicts around scarcity and political upheaval.
The main biofuels are ethanol and biodiesel. Biomass like wood can also be burned directly for fuel, although that usually produces more greenhouse gas emissions to produce the same amount of energy as burning fossil fuels. Biofuel greenhouse gas emissions are offset to a great extent because plants absorb and store carbon dioxide while they’re growing and sometimes in roots left in the ground, so CO2 emissions are roughly equal to or less than what the crops store.
Despite the advantages, numerous problems have led many to question whether biofuels are a green alternative. Andrew Steer and Craig Hanson of the World Resources Institute noted in the Guardian biofuel has three major strikes against it: “It uses land needed for food production and carbon storage, it requires large areas to generate just a small amount of fuel, and it won’t typically cut greenhouse gas emissions.”
Producing biofuel with crops like corn often requires converting land from food to fuel production or destroying natural ecosystems that provide valuable services, including carbon sequestration. Crops also require fertilizers, pesticides and large amounts of water, as well as machinery for planting, growing, harvesting, transporting and processing. If forests are cleared for fuel crops, and if the entire lifecycle of the fuels is taken into account, biofuels don’t always reduce overall greenhouse gas emissions. Palm oil, used for biodiesel, is especially bad, because valuable carbon sinks like peat bogs and rain forests are often destroyed to grow palms.
