Skip to main content

Between 17 million and 50 million acres of land dedicated to switchgrass production would be required to supplement waste and residue biomass to supply a large scale sustainable aviation fuel industry in the United States

In order to supply enough biomass to sustain the sustainable aviation fuel industry for the US domestic aviation market, approximately 49,087,671 acres of marginal land and 17,917,000 acres of productive land would be required. Whether choosing marginal land, productive land, or a combination of the two, the main environmental concern is the direct and indirect land use change (ILUC) that can occur as a result of the cultivation of switchgrass.

Sustainable aviation fuel from waste and residue biomass​

Previously, it was calculated that the amount of sustainable aviation fuel that can be produced from the near-term available waste and residue biomass in the United States is 6.62 billion gallons (25,083,800,000 L) of jet fuel per year. Therefore, to meet the stated goal of 50% of the United States domestic aviation fuel, which is equivalent to 13.03 billion gallons (49,322,756,505 L) of jet fuel per year, approximately 6.41 billion gallons (24,238,956,505 L) of jet fuel per year is required via the cultivation of switchgrass.

Constants​

Table 1: Constants for switchgrass yields

ConstantValueUnitsSources
Ethanol yield280L ethanol/ton dry biomass
Jet fuel yield2.0L ethanol/ L jet fuel
Sustainable aviation fuel required24,238,956,505L
Switchgrass yield (productive land)10tons/acre1

Switchgrass yields​

Figures for switchgrass yields for marginal land vary greatly depending on how the meaning of "marginal" is defined, and by how many extra inputs are used, such as fertilizers and irrigation. In this analysis, the average yield of 3.65 tons per acre per year with the use of nitrogen fertilizer is used as it is representative of the yields encountered in the literature for test plots and in computational modeling of marginal land yields in the United States.

Table 2: Switchgrass yields for marginal land

Author / InstitutionLocationYield (dry tons/acre/year)Source
Schmer et al.USA2.1 – 4.52
He et al.USA1.43
Mooney et al.Tennessee2.77 – 7.784
WrightVirginia4.35
WrightIowa2.88 – 3.475
Average3.65

Calculations​

From the sustainable aviation fuel required, the amount of ethanol that is required can be calculated

Ethanol required=Sustainable aviation fuel required×Ethanol yield=24,238,956,505 L×2.0 L ethanol/ L jet fuel=50,167,600,000 L ethanol/year\begin{align*} \text{Ethanol required} &= \text{Sustainable aviation fuel required} \times \text{Ethanol yield}\\ &= 24,238,956,505 \text{ L} \times 2.0 \text{ L ethanol/ L jet fuel}\\ &= 50,167,600,000 \text{ L ethanol/year} \end{align*}

Next, the tons of dry biomass that is required can be calculated

Dry biomass required=Ethanol requiredEthanol yield=50,167,600,000 L ethanol/year280 L ethanol/ton dry biomass=179,170,000 tons dry biomass/year\begin{align*} \text{Dry biomass required} &= \frac{\text{Ethanol required}}{\text{Ethanol yield}}\\ &= \frac{50,167,600,000 \text{ L ethanol/year}}{280 \text{ L ethanol/ton dry biomass}}\\ &= 179,170,000 \text{ tons dry biomass/year} \end{align*}

Finally, the amount of land required can be calculated for marginal land

Land required=Dry biomass requiredSwitchgrass yield (marginal land)=179,170,000 tons dry biomass/year3.65 tons/acre=49,087,671 acres\begin{align*} \text{Land required} &= \frac{\text{Dry biomass required}}{\text{Switchgrass yield (marginal land)}}\\ &= \frac{179,170,000 \text{ tons dry biomass/year}}{3.65 \text{ tons/acre}}\\ &= 49,087,671 \text{ acres} \end{align*}

And for productive land

Land required=Dry biomass requiredSwitchgrass yield (productive land)=179,170,000 tons dry biomass/year10 tons/acre=17,917,000 acres\begin{align*} \text{Land required} &= \frac{\text{Dry biomass required}}{\text{Switchgrass yield (productive land)}}\\ &= \frac{179,170,000 \text{ tons dry biomass/year}}{10 \text{ tons/acre}}\\ &= 17,917,000 \text{ acres} \end{align*}

Table 3: Summary of switchgrass cultivation requirements

Land typeYield (dry tons/acre/year)Land required (acres)
Marginal3.6549,087,671
Productive1017,917,000

Sources​

Footnotes​

  1. Downing, M., Eaton, L. M., Graham, R. L., Langholtz, M. H., Perlack, R. D., Turhollow, A. F., ... & Brandt, C. C. (2011). U.S. billion-ton update: Biomass supply for a bioenergy and bioproducts industry (No. ORNL/TM-2011/224). Oak Ridge National Laboratory. ↩

  2. Schmer, M. R., Vogel, K. P., Mitchell, R. B., & Perrin, R. K. (2008). Net energy of cellulosic ethanol from switchgrass. Proceedings of the National Academy of Sciences of the United States of America, 105(2), 464–469. https://doi.org/10.1073/pnas.0704767105 ↩

  3. He, Y., Jaiswal, D., Long, S. P., Liang, X.-Z., & Matthews, M. L. (2024). Biomass yield potential on U.S. marginal land and its contribution to reach net-zero emission. GCB Bioenergy, 16, e13128. https://doi.org/10.1111/gcbb.13128 ↩

  4. Mooney, D. F., Roberts, R. K., English, B. C., Tyler, D. D., Larson, J. A., Mooney, D. F., Roberts, R. K., English, B. C., Tyler, D. D., & Larson, J. A. (2008). Switchgrass Production in Marginal Environments: A Comparative Economic Analysis across Four West Tennessee Landscapes. Unknown. https://doi.org/10.22004/AG.ECON.6403 ↩

  5. Wright, L. (2007, August). Historical perspective on how and why switchgrass was selected as a "model" high-potential energy crop (ORNL/TM-2007/109). U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy. https://www.energy.gov/eere/bioenergy/articles/switchgrass-high-potential-energy-crop ↩ ↩2