American Carbon Registry

Currently active program (as of 1/2011).

Market Size and Scope
Offset Project Eligibility
Additionality Requirements and Project Methodologies
Project Approval Process


Type of Standard and Context

The American Carbon Registry (ACR) was founded in 1996 as the GHG Registry, the first private voluntary GHG registry in the US, by the environmental non-profit organzation Environmental Resources Trust (ERT). In 2007, ERT and its registry became part of Winrock International, a non-profit based in the US. The registry was re-branded as American Carbon Registry (ACR) in 2008. ACR published the most recent version if its American Carbon Registry Standard v2.1 in October 2010.  This document outlines the eligibility requirements for registration of project-based carbon offsets, and also includes requirements for methodology approval, project validation and verification, and other procedural requirements and information on the general use of the American Carbon Registry.  A summary of changes made in v2.1 (from 2.0) is available on the ACR website.

Standard Authority and Administrative Bodies

Oversight of ACR is provided by the Winrock International Board of Directors and ACR Advisory Council. The ACR director of has ultimate decision-making power for ACR-related decisions. Technical decisions are made by applicable Technical Committees, scientific peer reviewers and lead team member experts in the subject matter.

ACR’s standards are developed by ACR staff and staff of ACR’s parent organization Winrock International. Standards undergo public comment and  external scientific peer review. Methodologies are developed internally by Winrock staff or can be developed by third parties and brought to ACR for approval. All methodologies are approved via public comment and blind scientific peer review.

ACR approved verifiers can currently be chosen from a list on ACRs website or from verifiers who are approved under ANSI, CDM orJI. (ACR requires that all U.S. verifiers have begun the ANSI certification process by July 1, 2011.)

Regional Scope

ACR registers project-based carbon offsets from around the globe.

Recognition of Other Standards/ Linkage with Other Trading Systems

ACR methodologies and protocols are all based on International Standards Organization (ISO) 14064.
ACR allows project developers to use methodologies and tools for GHG measurement from the CDM and ACR-approved methodologies from EPA Climate Leaders to the extent that they comply with the ACR’s published standards.

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Market Size and Scope

Tradable Unit and Pricing Information

The American Carbon Registry holds serialized verified offsets called Emission Reduction Tons (ERTs). One ‘ERT’ represents the reduction or removal from the atmosphere equivalent to one metric ton of carbon dioxide. 

The World Bank reports that the average price of an ERT was USD 3.80 in 2008 and USD 3.40 in 2009. The 2010 State of the Voluntary Carbon Market report provides a range of ERT prices in 2009 from $3.25 to $22 and an average of $3.40 based on nine responses. ACR transaction / retirement volume in 2009 was just over 2 million tons.


The main buyers of ERTs include corporate pre-compliance buyers, hedge funds, carbon retailers and non-profit organizations.

Current Project Portfolio

ACR has issued over 30 million project based carbon offsets since 2005. As of Jan 2011, ACR has 23 projects in the active pipeline for registration, verification and issuance in 2011 (IFM, A/R, pneumatic controllers, biogas). ACR projects already registered that will issue offsets from new phases are not included in this number. Another 35+ new projects are in process for registering and issuing offsets in 2012 based on new methodologies recently approved or in development / approval process (N2O from fertilizer management, IFM public lands, wetlands restoration, rice production, REDD). For updated information, go here.

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Offset Project Eligibility

Project Types

ACR does not explicitly exclude any project types. All projects that meet the ACR Technical Standard are eligible for registration.
The following project types have been registered:

  • Anaerobic Digester Methane Destruction
  • Carbon Capture and Storage/Enhanced Oil Recovery
  • Energy Efficiency
  • Forest Carbon
  • Fugitive Methane Reduction
  • Fuel Substitution and Fuel Switching
  • Industrial Gas Substitution
  • Landfill Gas Utilization
  • Methane Capture, Flare and Utilization
  • Rural Solar Power
  • Truck Stop Idling

Project Size

There are no limitations for project size except for developing country indirect emissions from renewable energy projects , which have a limit of 100 MW.

Project Locations

There are no restrictions on project location.
Current registered projects are located in the US, Bolivia, Nicaragua and El Salvador.

Start Date 

The American Carbon Registry requires all project types, with the exception of forest projects, to have a start date that is no earlier than 1 January 2000. Forest and land-use-change projects with a start date of 1 November 1997 or later are eligible for ACR registration. Forest and land-use-change projects with an earlier start date will be evaluated on a case-by-case basis. 

Crediting Period

ACR non-forest projects have a crediting period of ten 7 years (unless otherwise specified) with opportunities for renewal. When the crediting period is over, project developers must re-verify the project, or cease to generate offsets from that project for ACR registration.
There are no restrictions on renewal as long as the project is verified to meet eligibility requirements.

AFOLU projects may have longer crediting periods, as specified in the ACR Forest Carbon Project Standard.  The crediting period is 40 years for Afforestation/Reforestation (AR) projects, 20 years for Improved Forest Management (IFM) projects (with the exception of stop-logging projects), 10 years for stop-logging IFM projects, and 10 years for all REDD projects. 

There are no restrictions on renewal as long as the project is verified to meet eligibility requirements.

Co-benefit Objectives and Requirements

Co-benefits are not required, but are desirable. Additional certifications such as CCB Standards can be used with ACR standards.

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Additionality Requirements and Project Methodologies

Additionality Requirements

All projects must have a clear project action that is different from what likely would have happened in the absence of the project. ACR requires every project to pass either an approved performance standard and a regulatory additionality test or a three-pronged test of additionality in which the project must:
1) exceed regulatory / legal requirements;
2) go beyond common practice; and
3) overcome one of three implementation barriers: institutional, financial or technical.

Project Methodologies

ACR allows the use of specific protocols from the CDM and select approved protocols from U.S. EPA Climate Leaders for calculating and updating baselines.  Baselines must be consistent with the WRI/WBCSD GHG Protocol and ISO 14064-2, and must be re-assessed in order to renew a crediting period.
ACR also develops its own project protocols and approves protocols developed by third parties. ACR has published a Forest Carbon Project Standard and a Livestock Waste Management Project Standard.  Furthermore, ACR is in various stages of developing methodologies for several project types:

    • Published: Nitrous Oxide (N2O) Emission Reductions through Changes in Fertilizer Management – This protocol is applicable to agricultural land management project activities that involve a change in fertilizer management including changes in fertilizer rate, type, placement, timing, use of timed-release fertilizers, use of nitrification inhibitors, and other factors.
    • Published: Conversion of High-Bleed Pneumatic Controllers in Oil and Natural Gas Systems – This protocol details requirements for oil & gas companies to reduce fugitive emissions of methane, a potent greenhouse gas, by retrofitting existing high-bleed pneumatic controllers with low-bleed options.
    • Published: Improved Forest Management through Increased Forest Carbon Sequestration – This protocol quantifies GHG emission reductions resulting from forest carbon projects exceeding baseline forest management practices, on privately owned timberlands exceeding 1,000 acres in the United States.
    • In Scientific Peer Review: REDD – Avoiding Planned Deforestation; and Livestock Waste Management.
    • In development: REDD – Avoiding Unplanned Deforestation and Degradation;Wetland Restoration and Preservation; Afforestation / Reforestation of Degraded Lands; Landfill methane; U.S. Improved Forest Management (IFM) performance standard;  and Carbon Capture and Storage (CCS).

    For an updated list and to download the methodologies, go here.

    If no protocol exists for a particular offset project type, the project developer may submit a proposed methodology to ACR for validation. ACR evaluates the methodology through a scientific peer review process. The developer may also work directly with the ACR to design a new methodology, which is also evaluated through a scientific peer review.

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    Project Approval Process

    Validation and Registration

    The steps to submit a project for offset registration are:

    1. Carbon offset project proponent submitsa GHG Plan (PDD) for review to determine eligibility .
    2. If project passes eligibility screening, it is ready for independent validation and verification from an American Carbon Registry approved verifier
    3. Once verified, the Registry issues and registers ERTs.


    Project developers are required to follow guidelines in the approved methodology.  ACR requires project developers to assess, account for, and mitigate leakage, and provide documentation to support mitigation assertions. Project developers must deduct all leakage that reduces the GHG emissions reduction and/or removal benefit of the project. ACR assesses leakage on a case-by-case basis.


    ACR requires projects to address the risk of reversal by use of one of the following:

    • an ACR-approved guarantee or insurance product; ;
    • dedication of offsets to the ACR-managed buffer pool.

    Monitoring, Verification and Certification

    ACR requires third party verification with an ACR approved verifier. Details on the verification process are presented in the ACR Verification Guideline for GHG Projects document.

    Registries and Fees

    The ACR provides an online registry system which allows members to register serialized offsets; record the purchase, sale, and retirement of ERTs; and report corporate GHG inventories. This information is accessible on the Carbon Registry page of the ACR website.

    Transaction fees depend on the type of transaction and vary between US$0.10 – US$0.14 per ERT transacted. ACR does not charge issuance fees

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