Auxiliary Fuel Use

This guide explains how to specify and manage auxiliary fuels within the LEAP (Low Emissions Analysis Platform) transformation processes, distinguishing them from feedstock fuels and detailing how to handle 'own use' consumption and feedback flows.

• Auxiliary fuels are defined as energy consumed per unit of energy produced or consumed in a process. They differ from feedstock fuels because they are not converted within the process, meaning their energy content is excluded from the overall energy efficiency calculations of that process.
• LEAP allows users to designate auxiliary fuels as 'own use' consumption if the fuel is produced by the same process that consumes it. This requires enabling the 'Meet auxiliary fuel use from this module's outputs (where possible)' option in the Transformation Module's Properties screen.
• When 'own use' consumption is enabled, LEAP handles fuel shortages by seeking requirements from lower transformation modules or imports. Additionally, emission factors are applied uniformly to all auxiliary fuel use, regardless of whether the fuel was produced internally or imported.
• Because 'own use' fuels are internal to a process, they do not appear in standard energy balance reports. Users must instead use the 'Outputs by Output Fuel' and 'Inputs' reports in Results View, utilizing Input Type and Output Type dimensions to track the split between net production and auxiliary use.
• In cases where an auxiliary fuel is consumed by a lower module but produced by a higher module (e.g., an oil refinery consuming electricity from a generation module), the system must iterate calculations to ensure production meets the additional demand, a process described as feedback flows.

APA

Stockholm Environment Institute (n.d.). Auxiliary Fuel Use. https://leap.sei.org/Help24/Transformation/Auxiliary_Fuel_Use.htm

Chicago

Stockholm Environment Institute. Auxiliary Fuel Use. n.d. https://leap.sei.org/Help24/Transformation/Auxiliary_Fuel_Use.htm.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=Auxiliary Fuel Use |url=https://leap.sei.org/Help24/Transformation/Auxiliary_Fuel_Use.htm |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitutendauxiliary, author = {{Stockholm Environment Institute}}, title = {{Auxiliary Fuel Use}}, institution = {Stockholm Environment Institute}, url = {https://leap.sei.org/Help24/Transformation/Auxiliary_Fuel_Use.htm}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }