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Carbon Accounting

Carbon Offset Standards, Methodologies and Protocols

The American Carbon Registry (ACR) registers voluntary carbon market projects that meet the ACR Standards, as described below. In addition, ACR has been approved by the California Air Resources Board (ARB) as an Offset Project Registry (OPR) for the California compliance market.

California Compliance Offset Protocols

To be eligible for compliance in the California cap-and-trade system, offset projects will be required to use ARB-approved compliance or early action offset protocols, to be verified by ARB-approved verification bodies, and to register on an ARB-approved Offset Project Registry (OPR) or Early Action Offset Program, such as American Carbon Registry. For more information on the California compliance offset program, see our California Offsets page.

American Carbon Registry Standards and Methodologies

The American Carbon Registry (ACR) publishes standards, methodologies, protocols and tools for greenhouse gas (GHG) accounting, which are all based on International Standards Organization (ISO) 14064 and sound scientific practice. ACR only registers project-based carbon offset tons that are real, additional, permanent and independently verified.

ACR process for development and approval of standards and methodologies is led by a qualified technical team. Approval includes review by ACR's technical team, a stakeholder comment period and a scientific peer review process, a rigorous technical review by experts in the relevant field(s). This combination of approaches ensures that our published standards and methodologies are the highest quality.

The Winrock and ACR team that leads the development of standards and methodologies includes internationally recognized leaders in the forestry, agriculture and clean energy sectors and is widely recognized for its deep expertise in carbon accounting.

New Methodologies

The American Carbon Registry promotes innovation to bring new offsets types to market. Project developers are welcome to submit new offset methodologies and methodology modifications for evaluation. New methodologies and methodology modifications are approved for use through ACR's public comment and scientific peer review process. Upon approval, ACR will publish the methodology for future use.

Other Accepted Methodologies

American Carbon Registry (ACR) generally accepts methodologies and tools approved for use by the Clean Development Mechanism (CDM). However, project proponents wishing to use a CDM methodology should first consult ACR for a review to include applicability as well as clarifications and/or conditions for its use for registration on ACR.

ACR may also elect to approve environmentally robust methodologies from other programs to the extent that they have been through a public stakeholder and technical peer review process and comply with ACR’s Standards.