Cited by 1,067Bioenergy crop production and managementBiofuel production and bioconversionEnergy, Environment, Agriculture Analysis

Net energy of cellulosic ethanol from switchgrass

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Schmer, M. R., Vogel, K. P., Mitchell, R. B., Perrin, R. K.·2008·Proceedings of the National Academy of Sciences

Abstract

Perennial herbaceous plants such as switchgrass ( Panicum virgatum L.) are being evaluated as cellulosic bioenergy crops. Two major concerns have been the net energy efficiency and economic feasibility of switchgrass and similar crops. All previous energy analyses have been based on data from research plots (<5 m 2 ) and estimated inputs. We managed switchgrass as a biomass energy crop in field trials of 3–9 ha (1 ha = 10,000 m 2 ) on marginal cropland on 10 farms across a wide precipitation and temperature gradient in the midcontinental U.S. to determine net energy and economic costs based on known farm inputs and harvested yields. In this report, we summarize the agricultural energy input costs, biomass yield, estimated ethanol output, greenhouse gas emissions, and net energy results. Annual biomass yields of established fields averaged 5.2 -11.1 Mg·ha −1 with a resulting average estimated net energy yield (NEY) of 60 GJ·ha −1 ·y −1 . Switchgrass produced 540% more renewable than nonrenewable energy consumed. Switchgrass monocultures managed for high yield produced 93% more biomass yield and an equivalent estimated NEY than previous estimates from human-made prairies that received low agricultural inputs. Estimated average greenhouse gas (GHG) emissions from cellulosic ethanol derived from switchgrass were 94% lower than estimated GHG from gasoline. This is a baseline study that represents the genetic material and agronomic technology available for switchgrass production in 2000 and 2001, when the fields were planted. Improved genetics and agronomics may further enhance energy sustainability and biofuel yield of switchgrass.

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Crossref · 10.1073/pnas.0704767105

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  • Switchgrass grown in Nebraska, North Dakota, and South Dakota had biomass yields ranging from 5.2 to 11.2 Mg ha-1 averaged over the third to fifth harvest years.

    “Switchgrass grown in Nebraska, North Dakota, and South Dakota had biomass yields ranging from 5.2 to 11.2 Mg ha -1 averaged over the third to fifth harvest years [17].”

    From Switchgrass Biofuel Production on Reclaimed Surface Mines: I. Soil Quality and Dry Matter Yield (2016) · cites this paper as [17]

    The Methods describe switchgrass fields in Nebraska, North Dakota, and South Dakota, and the NEV section reports average annual biomass yields of 5.2–11.1 Mg ha⁻¹ for established fields. The cited copy does not give the claimed upper value of 11.2 or explicitly identify that range as an average over the third through fifth harvest years. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • In other studies, switchgrass dry matter yields on marginal croplands varied from 5.0 to 10.0 Mg ha-1 annually.

    “In other studies, switchgrass dry matter (DM) yields on marginal croplands varied from 5.0 to 10.0 Mg ha -1 annually.”

    From Switchgrass Biofuel Production on Reclaimed Surface Mines: I. Soil Quality and Dry Matter Yield (2016) · cites this paper as [17]

    The NEV section reports annual biomass yields of 5.2–11.1 Mg ha⁻¹ for established switchgrass fields, and the Methods describe the fields as marginal cropland. This supports the setting and approximate lower bound, but the claimed upper bound of 10.0 Mg ha⁻¹ understates the reported 11.1. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • Schmer et al. (2008) found switchgrass yields of 5200 to 11,100 kg/ha on 10 farms of marginal cropland in the midwestern United States.

    “Schmer et al. (2008) found switchgrass yields of 5200 to 11,100 kg ha -1 on 10 farms of marginal cropland in the midwestern United States.”

    From Switchgrass Yield on Reclaimed Surface Mines for Bioenergy Production (2013) · cites this paper as Schmer et al., 2008

  • Schmer et al. measured annual average biomass yields of 5.2 to 11.1 Mg ha-1 of switchgrass when managed as a biomass energy crop on marginal cropland in the northern Great Plains, USA.

    “Schmer et al. [17] measured annual average biomass yields of 5.2 to 11.1 Mg ha -1 of switchgrass when managed as a biomass energy crop on marginal cropland in the northern Great Plains, USA.”
  • Results from life-cycle assessments of switchgrass grown for bioenergy have been mixed, due in large part to assigned net greenhouse gas emissions and assumptions made in indirect land conversion costs.

    “Results from life-cycle assessments (LCAs) of switchgrass grown for bioenergy, however, have been mixed [1,8,32,33], due in large part to the assigned net GHG emissions associated with switchgrass production and assumptions made in indirect land conversion costs.”

    From Soil Carbon Storage by Switchgrass Grown for Bioenergy (2008) · cites this paper as [32]

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Authors
Schmer, M. R., Vogel, K. P., Mitchell, R. B., & Perrin, R. K.
Affiliations
University of Nebraska–Lincoln (US)
Venue
Proceedings of the National Academy of Sciences
Published
2008-01-15
Volume
105
Issue
2
Pages
464-469
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2036849472
Cited by
1,067
References
43
Citations by year
2026: 6 · 2025: 11 · 2024: 15 · 2023: 20 · 2022: 24 · 2021: 31 · 2020: 40 · 2019: 25 · 2018: 48 · 2017: 50 · 2016: 57 · 2015: 91 · 2014: 98 · 2013: 121 · 2012: 102
FWCI
192.32
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Lincoln (University of Nebraska) (submittedVersion)
Funders
  • U.S. Department of Energy
  • University of Nebraska-Lincoln
  • Agricultural Research Service
  • Oak Ridge National Laboratory
Topics
  • Life Sciences › Agricultural and Biological Sciences › Agronomy and Crop Science › Bioenergy crop production and management
  • Physical Sciences › Engineering › Biomedical Engineering › Biofuel production and bioconversion
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Energy, Environment, Agriculture Analysis
Keywords
switchgrass, cellulosic ethanol, net energy yield, energy crops, biomass yield, greenhouse gas emissions, marginal cropland, perennial grasses, biofuel economics
MeSH terms
Agriculture, Air Pollutants, Ethanol, Cellulose, Conservation of Energy Resources, Conservation of Natural Resources, Energy-Generating Resources, Environment, Gasoline, Geography, Panicum, Midwestern United States, Greenhouse Effect, Biomass, Crops, Agricultural

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