What is going on with biofuels?
why tf I care, biofuel's backstory, and how to make corn into booze (Part 1)
Biofuels combine two of my favorite topics - biology and climate. It’s a story of single celled organisms fermenting away, a story of hardworking farmers across America. It’s a story of big government policy gone wild, and a story of climate change.
There is something elegant about the idea of growing plants for fuel: we grow plants for food, we grow plants to build our houses, and we can grow plants to run our cars. Growing plants to put in our gas tanks certainly seems better than endless Middle East wars, Gulf oil spills, and fracking. Unfortunately combusting any damn thing releases CO₂ into the atmosphere, and you do have to burn those plants as you drive your internal combustion engine around.
Right now we are experiencing an unprecedented boom in biofuels, driven by the old classics (ethanol) and the new hotness (renewable diesel). We should be having a healthy debate about these technologies - after all there are still 1 billion gas engines out there, and the Biden administration is heavily incentivizing biofuel growth. Is a “bridge fuel” a distraction from the climate crisis? Do biofuels “take away” from the food supply? Can we leverage the biofuel industry to make new, more valuable, bioproducts, for food, textiles, medicine, and beyond?
This is such a rich topic that I had to split it in two - part 1 talks about biofuel’s backstory in the US and the ethanol industry, part 2 covers renewable diesel and biofuel’s future.
Biofuel’s backstory
When biofuels were first considered in the early 20th century, they were seen as an agriculture generated fuel source that would provide the fuel for America’s mechanization - the first Ford model T was built to run on ethanol or gas. Biofuel was overtaken by the petroleum industry quite quickly, and by the 1920’s had fallen out of favor.
In the 80’s and 90’s in the US, policy began to form around supporting agriculture derived fuels. This was driven by the desire for a domestic fuel source to reduce reliance on foreign imports and the advent of a clean air policy. However, the most important factor here was surplus supply - growing yields in corn and soy pointed to ongoing surpluses for years to come. These crops were dedicated to biofuels starting in the 1980’s which by the mid-2000’s birthed the modern ethanol industry.
Biofuel’s mid-2000’s boom was fueled by the desire for domestic fuel sources, energy security, and policy incentives. Climate change and decarbonization were not part of the story. Biofuel’s bust in 2007/2008 was caused by rock bottom oil prices and reduced government support during the financial crisis.
Today, the story is different. Biofuel is produced from CO₂ from terrestrial sources which are already in the carbon cycle, so carbon is not added through the production and combustion of biofuels. The industry argues that it’s a bridge fuel (to EV) and a potential decarbonization solution… but it does still release CO₂ into the atmosphere from combustion.
There are two major types of biofuel worth discussing here: Ethanol and Renewable Diesel.
Corn ethanol
Briefly, ethanol is generated through the fermentation of corn or other cellulosic feedstock with yeast.
The corn is milled (ground into a meal made up of mostly starch), water is added to make a slurry, enzymes are added, and the starch breaks down into simple sugars. Yeast is added for fermentation, producing ethanol, and the material is distilled (to concentrate the ethanol) and dehydrated to remove water.
In the early days of the ethanol biofuel industry there was little regard for the product left at the end of distillation: a mix of corn fiber, yeast protein, and distilled corn oil called “Dry Distillers Grain with Solubles” (DDGS). In the 90’s and early 2000’s this was dried out and used as feed for the beef and dairy industry.
DDGS has a component that is now highly valuable: vegetable protein. There is huge demand, as evidence by massive scaling in the soy processing industry, with new plants being built all over the US. The driver is world protein demand for soybean meal. Biofuel producers realized they were wasting something by sending it off to the cattle industry.
New separations technology developed in the last 5 years allow farmers to isolate pure protein (yeast derived), fiber, and distillers corn oil. This post ethanol production protein can go into pet food, poultry, swine feed, and aquafeed.
Corn producers are making tons of ethanol, delivering more year over year as corn yields increase, but they are only allowed to blend 10% Ethanol into automotive fuels. It’s unknown how much more room there is to grow if demand remains capped.
Sugar ethanol
Sugar cane is another substrate for ethanol fermentation, particularly prevalent in Central and South America. Its biggest challenge is that sugar has to be processed nearly immediately after harvest, unlike corn which can be stored during poor margin periods. Surpluses have to be exported and make the economics of the business far more challenging.
Brazil recognizes this challenge and is diversifying away from cane - they are already #1 in soy production, and are likely to be #1 in corn / corn ethanol. One knock-on effect of ethanol demand growth may be deforestation in the Amazon.
Carbon capture
Surprisingly, the US ethanol industry is at the leading edge of Carbon capture efforts.
For each corn kernel, ⅓ will be released as CO₂ during the fermentation process, ⅓ becomes alcohol, and ⅓ is DDGS. Historically the CO₂ was released into the atmosphere, but now they are beginning to implement technology to capture and sequester the Carbon emissions. The CO₂ from fermentation is highly pure, so no “scrubbing” is necessary.
In fact there is a massive CO₂ pipeline being built by Summit Carbon Solutions snaking its way across the great plains, collecting CO₂ emissions from farms and piping them somewhere (underground?)
This is why the biofuel industry makes the argument that this is a sustainable fuel - ethanol, protein/fiber, and captured CO₂. Seems pretty carbon neutral right?
Part 2
Stay tuned for part two where we talk renewable diesel, the new drop-in fuel on the scene, driving a massive run up in vegetable oil prices. I’d also like to get an honest assessment of whether biofuels are a viable climate solution, or a house of cards propped up by government subsidies. Lastly, there are lots of great products to be made using fermentation - could the biofuels industry support scaling of sustainable bioproducts?