Biofuels scale up plans are the thermodynamic inverse of one of Homo Sapiens’ most profound life transformations–our ability beginning about a century ago to harness fossil energy to facilitate food production. We did so though electrification, mostly gas and coal-powered that opened more acreage to the plow. Those plows rapidly stopped being pulled by horses and instead were animated by diesel and gasoline motors. And we could access synthetic fertilizers at a scale that guano and saltpeter mines never could have sustained.
In short, we brought the energy density that had been stored underground for millions of years and supercharged our agriculture with it. Biofuels however, generally move precisely the opposite direction–trying to turn lower energy density grains and oilseeds into higher energy density fuels that can supplant oil products. Scaling this process up to meet even a fraction of present and foreseeable global energy needs would place incredible tensions on the already strained energy-food-water nexus.
Biofuels’ Fertilizer and Land Footprints
Just consider the land and fertilizer footprints of a million barrels/day of biofuels. Producing a million bpd of ethanol from corn likely requires about 27 million acres of land–approximately 4 times the area of Massachusetts. Obtaining a million barrels/day of soybean oil biodiesel likely requires a land area about the size of Texas. This is the price of moving backwards down the energy density chain. To boot, each million bpd of ethanol require almost 2% of global nitrogen fertilizer use and about 135 million tonnes of corn/year–an amount that by itself would be one of the largest consumers of corn on the plant, trailing only China and the United States itself.
Exhibit 1
Sources and Methodology Notes at End of Article
In this author’s view, expanding biofuels production beyond present levels will be incredibly challenging given the constraints outlined above. Indeed, at present the US already consumes 10-11% of the entire global corn crop to displace about 2.5% of total global gasoline use. The leverage simply goes the wrong way. And even if ethanol production were doubled or tripled and displaced more crude-derived fuels from the US market, gasoline prices would still fundamentally price based on world oil market dynamics.
“Crude to Food” Linkages Would Likely Tighten Further
Furthermore, adding 1 million bpd of biogasoline or biodiesel to markets that for each fuel are over 25 times larger than that would likely reinforce the “crude to food” price correlation that has emerged over the past 15 years.
Exhibit 2: Crude oil vs. Corn Pricing, Index January 1990=1 and Correlation Analysis Over Time
Source: IMF (via Federal Reserve Bank of St. Louis), Author’s Analysis
Further Reading:
Sources and Methodology:
•Corn Following Soybeans:
•2023-24 US corn use for ethanol of 5.465 billion bushels (139 MMT),
•2023 US ethanol production of 15.62 x 10^9 gallons (371.9 mmbbl or ~1 mmbl/d),
•Iowa high end corn yield = 204 bu/ac
•Implied land use for ethanol prod = 26.8 million ac
•Effective ethanol yield = 13.9 bbl/ac
•N fert use = 151 lbs/ac (11 lbs/bbl)
•P fert use = 83 lbs/ac (6 lbs/bbl)
•K fert use = 67 lbs/ac (4.8 lbs/bbl)
•Assume N fert in anhydrous NH3 directly applied. In 2020, producing 72% of global ammonia supply (total 185 MMT, gas-derived sub-total 133 MMT) required 170 BCM of natural gas, for an input level of 1278 M^3 of natgas/tonne of NH3 or 0.6 M^3 (20.6 ft^3) of gas per lb of NH3.
•20.6 ft^3 * 11 lbs/bbl ÷ 1000 ft^3/MMBTU = 0.23 MMBTU of gas-derived N fert/bbl of ethanol
•Total 2024 machinery cost of $183.75/ac for Iowa corn following soybeans farm. Assume 50% is variable cost and that 80% of that is fuel with diesel @ $3.38/gal. Implies diesel use of 22 gal/ac. At 0.133 MMBTU/gas diesel, implies machinery use of 2.95 MMBTU/ac or 0.21 MMBTU/bbl
•Corn drying energy use of 6.6 gal LP gas/acre @ 204 bushels/ac. 6.6 gal LP ÷ 13.9 bbl/ac = 0.5 gal LP/bbl. At 91,500 BTU/gal of LP, this means 0.046 MMBTU/bbl of LP input per bbl of ethanol.
•Ethanol plant energy use of 25,000 BTU gal or 1 MMBTU/bbl
•
•Sources:
•https://ethanolproducer.com/articles/usda-increases-estimate-for-2023-24-corn-use-in-ethanol
•Ethanol production: https://d35t1syewk4d42.cloudfront.net/file/2666/RFA_Outlook_2024_full_final_low.pdf
•NH3 production information: https://iea.blob.core.windows.net/assets/6ee41bb9-8e81-4b64-8701-2acc064ff6e4/AmmoniaTechnologyRoadmap.pdf
•Ethanol plant energy use: Lee, U., Kwon, H., Wu, M. and Wang, M. (2021), Retrospective analysis of the U.S. corn ethanol industry for 2005–2019: implications for greenhouse gas emission reductions. Biofuels, Bioprod. Bioref., 15: 1318-1331. https://doi.org/10.1002/bbb.2225
•Crop budget data: https://www.extension.iastate.edu/agdm/crops/pdf/a1-20-2024.pdf
•Non-herbicide Tolerant Soybeans Following Corn:
•2023-24 US soybean production of 4.2 billion bushels (114 MMT),
•2023-24 US soybean oil to biofuels of 13 billion lbs or 1.7 billion gallons or 40.4 million bbl (~111 thousand bpd of soybean oil)
•Assume 95% conversion rate
•Iowa high end soybean yield = 65 bu/ac
•10.7 lbs of soybean oil per bushel ÷ 7.7 lbs/gal * 65 bu/ac * 0.95 yield rate = 86 gal or ~2 bbl of biodiesel/acre
•Implied land use for soy biodiesel prod = 18.8 million ac
•Effective soy biodiesel yield = 2.04 bbl/ac
•N fert use = N/A
•P fert use = 47 lbs/ac (23 lbs/bbl)
•K fert use = 89 lbs/ac (43.6 lbs/bbl)
•Total 2024 machinery cost of $104/ac for Iowa soybeans following corn farm. Assume 50% is variable cost and that 80% of that is fuel with diesel @ $3.38/gal. Implies diesel use of 12.3 gal/ac. At 0.133 MMBTU/gas diesel, implies machinery use of 1.64 MMBTU/ac or 0.8 MMBTU/bbl
•Sources:
•NH3 production information: https://iea.blob.core.windows.net/assets/6ee41bb9-8e81-4b64-8701-2acc064ff6e4/AmmoniaTechnologyRoadmap.pdf
•Ethanol plant energy use: Lee, U., Kwon, H., Wu, M. and Wang, M. (2021), Retrospective analysis of the U.S. corn ethanol industry for 2005–2019: implications for greenhouse gas emission reductions. Biofuels, Bioprod. Bioref., 15: 1318-1331. https://doi.org/10.1002/bbb.2225
•Crop budget data: https://www.extension.iastate.edu/agdm/crops/pdf/a1-20-2024.pdf Bushel conversion: https://www.cfd.coop/go/doc/f/CMDT_Tables_for_Weights_and_Measurement_for_Crops.pdf
Leave a Reply