Climate change is one of the top issues of our time. Wind power, solar energy and electric cars grab a lot of headlines as solutions. Biofuels hold promise too, as part of a varied approach to our energy needs.
The most recent issue of Sustainable, Secure Food Blog explains the benefits of biofuels and how crops are used to make them. According to Matt Herman of the National Biodiesel Board, “biofuels are a low-carbon fuel option that we can use to make a difference right now.
Many states are already using ethanol as part of their gasoline supply systems. In California, biodiesel and renewable diesel made up over 25 percent of the fuel used for diesel engines in 2020. Some crops are better suited than others to be processed into biofuels.”
There are two main sources of biofuels: carbohydrate winners and oily sources.
Corn is used for biofuel generation because of its capacity to make a lot of carbohydrates from sunshine. It’s categorized as a “C4” plant, which means it is very efficient at taking sunlight and creating carbohydrates. Other C4 food plants include sorghum and sugar. Grasses, like miscanthus, are also grown as biofuel sources. When processed into biofuels, carbohydrates become ethanol.
While mainly carbohydrate, the processing of corn to ethanol still provides a significant amount of protein for animal feed and carbon dioxide for a variety of industrial applications.
Soybeans are one crop used to make biodiesel and renewable diesel, particularly from the oil generated by soybeans. Soybeans are also nitrogen fixers, which means they can be beneficial for the soil. In addition, soybeans contain proteins, which can be separated out in processing. Due to the growing demand for protein from soybeans, we produce more vegetable oil than we can consume in the U.S. This extra oil has opened the door for the cost-effective production of biodiesel, and soon, sustainable aviation fuel from soy oil.
A new type of fuel: Renewable diesel production
Renewable diesel is a different fuel than biodiesel but is made from the same fats and vegetable oils. Renewable diesel is a hydrocarbon produced through chemical processes such as hydrotreating. This method uses high pressure hydrogen to remove the oxygen, which is converted to water. After more steps, the resulting product is chemically identical to petroleum diesel.
Because a different process is used for processing soy, different byproducts called renewable propane and renewable gasoline are made. These two products can reduce greenhouse gas emissions compared to petroleum.