Work

Green-Hydrogen Energy Share: An Intuitive Metric to Compare Energy Density and H 2 Efficiency in Biofuels and E-Fuels

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide This communication proposes two indices to quantify hydrogen utilization efficiency and compare biofuels and e-fuels on a common energy basis: Hydrogen-Energy Share coefficient, HES [MJ H2 /kg fuel ], and its complementary, Hydrogen Energy fraction, HES% [MJ H2 /MJ fuel ]. Mass- and energy-balanced data sets are normalized to 1 MJ of produced-fuel (lower heating value). External-energy demand is disaggregated into feedstock provision, synthesis-plant operation, and renewable power for green hydrogen (G-H2) electrolysis. Then, the metrics are applied across 11 industrially relevant pathways, 5 e-fuels, and 6 biomass-to-liquids biofuels, as a compact demonstration data set. The analysis is restricted to liquid fuel routes; hydrogen storage vectors (e.g., ammonia and LOHCs) are outside the present scope. Total energy input spans an order of magnitude, from 0.19 MJ H2 /MJ HVO to 2.62 MJ H2 /MJ e-FT . In e-fuel pathways, most input is the electricity used to produce G-H 2 (1.6–2.0 MJ H2 /MJ e-fuel ) with HES up to 60 MJ H2 /kg e-CH4 and HES% ≥ 100%. Bioroutes use little electrolytic hydrogen but depend on sustainable biomass y (0.08–1.06 MJ biomass /MJ biofuel ); HES ranges 3–38 MJ H2 /kg biofuel and HES% ≤ 80%. Defined purely from energy balances, HES/HES% are proposed as first-order hydrogen-energy metrics to be used alongside, rather than instead of, detailed techno-economic and environmental assessments. These indexes make the electricity-versus-biomass trade-off explicit and intuitive in the deployment discussion: bioroutes where low-carbon power is scarce but biomass is available, electrofuels where cheap clean power and concentrated CO 2 are colocated.

Source: ACS Omega

DOI: 10.1021/acsomega.5c09592

Authors: Ada Robinson Medici, Aristide Giuliano, Nicola Pierro, Isabella de Bari, Stavros Papadokonstantakis

Institutions: TU Wien, National Agency for New Technologies, Energy and Sustainable Economic Development

Language: English

Topic: Hybrid Renewable Energy Systems

Subfield: Energy Engineering and Power Technology

Field: Energy

Domain: Physical Sciences

SDGs: Affordable and clean energy, Climate action

Open Access status: gold

Estimated APC paid: $1,935