Bridge Processes

Overview¶

Bridge processes are designed to provide transparent connections between repositories. Where an exchange uses a technosphere flow generated by a process in another repository, consider a bridge process.

Current Implementation¶

The following repositories implement bridge processes to connect to other repositories:

• Heavy Equipment to NETL coal and USLCI
• FHWA to USLCI
• USFS to USLCI and eLCI
• CDD to USLCI, USEEIO, eLCI, Heavy equipment, NETL coal
• ANL Concrete to USLCI

Guidance¶

Section 1: Using Duplicate Technosphere Flows¶

When the technosphere flow and units are the same in both repositories AND there is only one possible provider, do not use a bridge process. Instead,

• Export the flow from its source repository
• Ensure that the flow UUIDs match in the origin repo and the new repo
• Ensure that the upstream process/provider of the flow is not stored in the new repo
  • To export just the foreground processes and flows of an openLCA database. Export as a JSON, select only the processes of interest and do not select the checkbox: Export default providers of product inputs and waste outputs
• Track the flow using a tag on the flow with the repo of origin’s name (e.g., USLCI, US Electricity Baseline, etc.)
  • Communicates to users that a flow is NOT A CUTOFF but requires importing another database
• The technosphere flow should be placed in the same NAICS folder as the origin repo.
• Include Repository-level metadata about which repositories might be needed, e.g., For more complete supply chains, this database should be used with the USLCI and U.S. Electricity Baseline.
• Note: These instructions apply to both technosphere flows with providers and those without (cut-off flows).

Section 2: Using Bridge Processes¶

A bridge process SHOULD be used when:

1. the exact technosphere flow is used, but there are multiple possible providers, OR
2. the target technosphere flow is not quite identical and serves as a proxy flow to avoid orphan flows.

To create a bridge process:

• Follow the instructions in Section 1 to establish the flow which will be bridged to.
• Bridge processes should be placed in a separate folder “Bridge Processes” and include subfolders named “Repo X to Repo Y”, and be named using the format"RelevantFlowName Bridge; Repo X to Repo Y".
  • The folder and process names are specific to the target repo to help users quickly identify what other repos they need to import.

When Bridge processes are used for multiple possible providers:

• Use the same flow as both the input and output in the bridge process.
• The process description should indicate 1) that this is a bridge process and 2) which provider should be connected.

"This process links an input in a Forestry and Forest Products process to a provider from the Electricity Baseline repository on the Federal LCA Commons. The intended provider for this process is “Electricity; at user; consumption mix - US - US”.

When Bridge processes are used to implement conversions or connect to proxy flows:

• Any conversions or manipulations should be documented in the process Description field. This includes, for example, unit conversions (energy to mass) or stoichiometric conversions.