Description

  1. Algal biofuels have been investigated as an alternative to traditional fossil fuels for transportation in the United States since the 1970s. Yet after five decades of development, scalability and implementation remain limited. To evaluate the state of progress, this study harmonized energy inputs and outputs across 39 papers, encompassing 508 observations on the production of algal biofuel energy return on energy investment (EROEI) in the United States. The analysis produced a mean EROEI of 1.01—essentially the break-even point—irrespective of system boundaries. This is lower than bioethanol (2.8) and far below oil (8.7). Life-cycle analysis results showed that hydrothermal liquefaction in algal diesel production yielded a slightly higher mean EROEI (0.67) than transesterification (0.51). Co-products were found to play a significant role in reported EROEI values, particularly those recycled into production processes. Collectively, these findings indicate that investment to date has not produced a competitive technology. This evidence suggests that continuing to invest heavily in algal biofuels as a primary pathway for the energy transition is unlikely to yield competitive results in the near to medium term. For this reason, algal biofuels show little potential to alleviate the ongoing decline in the EROEI of petroleum and are not a promising renewable energy option for reducing greenhouse gas emissions from the transportation sector. They also show little promise for alleviating the land use, food vs fuel and other controversies that have plagued first and second-generation biofuels.

Author ORCID Identifier

0009-0004-4146-7894

Document Type

Dataset

DCMI Type

Dataset

File Format

.xlsx

Viewing Instructions

Special software required to use data: The Researcher used SPSS, but in this format, any statistical analysis program would work.

Publication Date

11-5-2025

Publisher

Utah State University

Methodology

In conducting a meta-analysis of the EROEI of algal biofuels studies, we employed the following steps.

i. Algal biofuel EROEI studies dating back to 2000 were collected and examined for inclusion,

ii. Relevant production data and system boundaries were gathered for each study included, and

iii. The mean EROEI for algal biofuel production was calculated.

iv. Mean EROEI were calculated for algal biofuel production when including certain processing steps or co-products.

Of these, 475 values included one or more co-products, defined as any product generated during algal biofuel production that contributed either an energy input or a marketable energy output. Due to limitations in the available data, the energy value of the bio-fuel could not be disaggregated from the co-product energy contributions; therefore, the reported EROEI values are presented as they were published.

Referenced by

Arnold, Michelle M., David J.R. Murphy, Christopher L. Lant (In review) “Energy Input-Output Analysis Reveals Algal Diesel Struggles to Break Even.” Energies

Language

eng

Code Lists

Ob. = Observation
EROEI = Energy return on energy investment

Disciplines

Natural Resources and Conservation | Oil, Gas, and Energy

License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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Additional Files

README_Arnold_ch3.txt (5 kB)

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