Proposed new yellow grease production processes for the settling rendering method (pre-publication)
Date: November 8, 2024
1. Purpose
The purpose of this pre-publication is to present proposed new yellow grease production processes from the settling rendering method in the Fuel Life Cycle Assessment (LCA) Model (the Model) for the next formal publication in 2026.
With this pre-publication, Environment and Climate Change Canada (ECCC) provides a description of the proposed changes to the Model, including a description of the methodology, data sources and assumptions for the processes. It also provides the carbon intensities (CIs) associated with the proposed changes that can be used to assess the implications on the results generated by the Model and allow stakeholders to provide comments on this pre-publication.
Pre-publications are not to be used for compliance with the Clean Fuel Regulations or other programs or regulations unless otherwise specified.
The CIs presented in the pre-publication may differ from those included in the next formal publication of the Model based on comments received and other changes implemented in the Model.
This pre-publication includes descriptive documents and an openLCA module. The module includes, for each new yellow grease process, a system process located in the Data Library folder of the Model Database and a unit process located in a new folder named Background Modelling. The system processes contain the rolled-up CI, while the unit processes showcase the inputs and outputs for each process. The unit processes were developed to increase transparency with disaggregated data. This pre-publication also contains three new configurable processes located in the Fuel Pathways folder.
2. Context
Yellow grease is used as a feedstock in the production of biodiesel. It is made from raw used cooking oil (UCO) which is collected from restaurants and transported by trucks to the rendering plants. Once at the rendering plant, the water content of the raw UCO is removed using either the traditional or settling rendering method.
Currently, the Model only contains processes representing the traditional UCO rendering method which consists of high-temperature cooking and tricanting to remove water from the UCO. The natural gas and electricity inputs for UCO processing are based on Xu et al. (2022). The thermal requirements are based on a theoretical calculation with no energy recovery. This is typical of most rendering operations.
The Model also contains yellow grease production configurable processes modelled from the Canadian yellow grease process, representing the traditional rendering method, available in the Data Library. These unit processes are partially modelled and allow the user to replace certain flows with other flows representing their situation (related to electricity and transport).
For more information on the current modelling methodology, please refer to Chapter 3.5.6 and 4.2.7 of the Fuel LCA Model Methodology.
3. Description of the proposed changes to the Model
For the next formal publication of the Model, planned in 2026, ECCC is proposing to add processes to represent UCO processing at the rendering facility using the settling process rendering method. A literature review indicated that 25% of UCO renderers, representing 39% of facilities covered by a North American Renderers Association (NARA), use the settling method to reduce energy demand (Xu et al., 2022). Because the settling rendering process involves the settling of raw UCO after a heating process, it is less energy-intensive than the traditional rendering method where water is evaporated via high-temperature cooking.
It is therefore proposed to introduce the following new processes in the Data Library\Feedstocks\UCO and yellow grease folder.
- Yellow grease production, from UCO, settling rendering, at processor gate [CA-AB]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-BC]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-MB]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-NB]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-NL]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-NS]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-ON]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-PE]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-QC]
- Yellow grease production, from UCO, settling rendering at processor gate [CA-SK]
- Yellow grease production, from UCO, settling rendering at processor gate [CA]
It is also planned to add three new configurable processes for yellow grease in the Fuel pathways\Configurable processes\Yellow grease folder of the Model Database to account for the settling rendering method.
- Yellow grease, from UCO, settling rendering, at processor gate, configurable A
- Yellow grease, from UCO, settling rendering, at processor gate, configurable B
- Yellow grease, from UCO, settling rendering, at processor gate, configurable C
The current yellow grease processes in the Data Library and configurable processes will also be renamed in the next formal publication to specify that they refer to the traditional rendering method.
The new yellow grease processes will incorporate specific energy use values associated with the settling rendering method based on Table 2 of the Xu et al. (2022).
The UCO transport distance from the restaurant to the rendering facility used in the modeling is the same as the one for the yellow grease processes for the traditional rendering method currently in the Model (taken from R&D GREET 2023 Revision 1).
The CIs for the proposed new processes are available for public review in Annex A of this descriptive document and in a module that can be uploaded in openLCA.
Annex B presents the proposed revised sections of the Fuel LCA Model Methodology.
4. Instructions for importing the module
The module is available in the folder Proposed-new-yellow-grease-production-processes-for-the-settling-rendering-method of the ECCC Data Catalogue and can be imported either into an empty database or directly into the Model Database.
Importing the module into an empty database allows users to see only the new and revised processes. No CI calculations can be performed when importing the module into an empty database.
Importing the module into the Model Database allows users to recalculate CIs without any additional steps. However, it is important to note that the import of the module in the Model database will update the values of the existing processes, and as such, the changes are irreversible. Consequently, users should always import the module into a copy of their original database.
For more information, please refer to the Instructions on how to import a module into openLCA.
5. How to submit comments on this pre-publication
Stakeholders are invited to review this pre-publication and provide comments to ECCC within 30 days following the pre-publication at modeleacvcarburant-fuellcamodel@ec.gc.ca.
Please indicate the following in the subject line: Comments on the pre-publication: Proposed new yellow grease production processes for the settling rendering method. Comments submitted will be considered for the development of the next formal version of the Fuel LCA Model.
For any questions related to this pre-publication, please contact modeleacvcarburant-fuellcamodel@ec.gc.ca with the following subject line: Questions on the pre-publication: Proposed new yellow grease production processes for the settling rendering method.
Annex A – CIs for the proposed new yellow grease production processes for the settling rendering method
The CI values presented in this Annex use the global warming potential (GWP) for the 100-year time horizon of the International Panel on Climate Change (IPCC) 5th Assessment Report (AR5). For more information, please refer to section 2.8 of the Fuel LCA Model methodology.
| Province/Territory | CI (g CO2e/kg yellow grease) |
|---|---|
| Canada | 69.8 |
| Alberta | 81.4 |
| British Columbia | 67.4 |
| Manitoba | 67.1 |
| New Brunswick | 74.6 |
| Newfoundland | 67.6 |
| Nova Scotia | 84.8 |
| Ontario | 67.5 |
| Prince Edward Island | 66.5 |
| Quebec | 66.9 |
| Saskatchewan | 86.1 |
Annex B – Proposed revised methodology
The methodology for the yellow grease processes and configurable processes in the current version of the Model can be found in Chapters 3.5.6 and 4.2.7 of the Fuel Life Cycle Assessment Model Methodology.
The following sections provide the proposed changes to the Methodology that will be reflected in the next formal version of the Model. Note that the section numbers and text could change for the next formal version of the Fuel LCA Model Methodology.
3.5.6 Raw used cooking oil (UCO) and yellow grease
Modelling approach for yellow grease production from raw UCO
The boundary of the raw UCO process begins with the production of the raw UCO at the restaurants and ends with the restaurant gate. The upstream GHG emissions related to the raw UCO are not included in the dataset since the oil is considered a waste. This process allows Model users to choose raw UCO as feedstock for biodiesel plants that use raw UCO at their facility instead of receiving yellow grease from a rendering plant.
For yellow grease, the boundary of the process begins with the raw UCO at the restaurants and ends with the UCO processing at the rendering facility.
The transport of the raw UCO to the rendering facility considers a trucking distance of 313.6 km calculated using the shares of transportation 1) to rendering plants directly and 2) via a bulk transfer tank before being transported to the rendering plant (R&D GREET 2023 Revision 1). The Model assumes an average payload of 45 tonnes.
The Model includes processes for two rendering methods for UCO processing at the rendering facility (traditional and settling method), both of which include removing water from the UCO with mechanical and thermal processes. The modeling takes into account that UCO has a water content of 26% based on the quantity of raw UCO (1.35kg) needed to produce 1 kg of yellow grease at the rendering plant (Xu et al. [2022]). The traditional UCO rendering method, which involves high-temperature cooking and tricanting, requires 2.11 MJ of natural gas and 0.25 MJ of electricity per kg of yellow grease (Xu et al. [2022]). The settling rendering method, which involves heating raw UCO and then letting it settle, uses 0.076MJ of natural gas and 0.09MJ of electricity per kg of yellow grease (Xu et al. [2022]).
Geographical scope for yellow grease production from raw UCO
The Model includes processes defined at the provincial and national levels for yellow grease production in Canada. Processes only differ in the provincial electricity grid mix used in the purification process. This assumes that the purification process does not differ across Canada, and only the emissions related to electricity differ.
Allocation for yellow grease production from raw UCO
No allocation is required for the production of yellow grease from raw UCO.
Data sources for yellow grease production from raw UCO
- Argonne National Laboratory. 2023. R&D GREET 2023 Revision 1: The Greenhouse gases, Regulated Emissions, and Energy use in Technologies Model. UChicago Argonne, LLC under contract DE-AC02-06CH11357 with the U.S. Department of Energy.
- Xu, Hui, Ou, Longwen, Li, Yuan, Hawkins, Troy R. Hawkins, and Wang Michael. 2022. Life Cycle Greenhouse Gas Emissions of Biodiesel and Renewable Diesel Production in the United States. Environmental Science and Technology, Volume 56, Issue 12, 7512−7521. DOI: 10.1021/acs.est.2c00289.
4.2.7 Modelling approach for yellow grease configurable processes
The yellow grease configurable processes for both the traditional and settling rendering methods were modelled from the Canadian yellow grease production processes available in the Data Library (Chapter 3.5.6). The yellow grease CI was calculated excluding electricity and raw UCO transport inputs. The CI results were then added to the outputs of the configurable processes, while an electricity dummy flow, a ship transport, a train transport, and local and international truck transports (25 tonnes and 45 tonnes payloads) flows were added as inputs.
A default electricity consumption of 0.069 kWh (traditional rendering) and 0.025 kWh (settling rendering) are assigned to the dummy flow. A default trucking distance of 423.36 kg*km (representing the load-distance over the default trucking distance of 313.6 km) is assigned to the domestic 25 tonnes truck payload (both traditional and settling rendering). The other transport flows are set at zero.
The user can replace the dummy flow with an electricity flow to represent the grid mix of their geographical location and add the calculated load-distance to all transport modes that are applicable. If a mode is not used, the user leaves it at zero.
All data sources for this configurable process are listed in Chapter 3.5.6.
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