Â
Our recent workshops and studies (Link:Â Â CANES NES TR-23Â )Â have developed a strategy to replace all crude oil with low-carbon drop-in biofuels using cellulosic feedstocks without significant impacts on food and fiber prices. Existing biofuels plants use biomass as (1) a carbon source for the hydrocarbon product, (2) a carbon source to react with the oxygen (40% by weight) in biomass to remove that oxygen as carbon dioxide, and (3) an energy source to operate the process, By substituting external heat and hydrogen to operate the process and remove the oxygen from the biomass as water, the quantities of hydrocarbon biofuels per unit of cellulosic biomass increases by two to four. One can also use forms of biomass as feedstocks not suitable for traditional biofuels processes. As a consequence, there is more than sufficient cellulosic biomass to replace crude oil with hydrocarbon biofuels (gasoline, diesel, jet fuel, chemical feedstock).
Because plants remove carbon dioxide from the air, the burning of biofuels does not increase atmospheric carbon dioxide levels—carbon neutral. This option requires massive heat and hydrogen inputs at large integrated refineries. The heat can be provided by nuclear reactors. Hydrogen can be provided by (1) steam methane reforming of natural gas to produce hydrogen with sequestration of carbon dioxide and (2) using nuclear reactors to produce hydrogen. Drop-in replacements for crude oil provide a rapid route to decarbonize about half the U.S. economy with major benefits to the rural economy. Because we only want the carbon and hydrogen to produce hydrocarbon biofuels,  we can recycle the nutrients (phosphorous, potassium, etc.) back to the soil to improve long-term soil properties while sequestering carbon in the soil. This is in contrast to food and fiber production where we require those trace nutrients for healthy food and useful fiber/timber products.
Charles Forsberg
Massachusetts Institute of Technology