You are here: Home » How it Works » What We Do

What We Do

In both the voluntary carbon market and California's regulated carbon market, ACR oversees the registration and verification of carbon offset projects following approved carbon accounting methodologies or protocols and issues offsets on a transparent registry system. Each offset represents the reduction or removal from the atmosphere equivalent to one metric tonne of carbon dioxide. The offsets products are specific to ACR's distinct operations in the California compliance market and the global voluntary carbon market.

California's regulated carbon market

As an approved Offset Project Registry (OPR) for the California Cap-and-Trade program, ACR works with the state regulatory agency, the Air Resources Board (ARB), to oversee the listing and verification of carbon offset projects developed using ARB's compliance offset and early action offset protocols. 

For projects registered under California compliance protocols or early action quantification methodologies and verified by an accredited verification body, ACR issues Registry Offset Credits (ROCs) and Early Action Offset Credits (EAOCs). These offset types are both eligible to be converted to ARB compliance Offset Credits, which can be used by California entities to help meet their emissions reductions obligations in the Cap-and-Trade Program.

Voluntary carbon market

In the voluntary market, ACR oversees the registration and independent verification of projects that meet ACR Standards and follow ACR approved carbon accounting methodologies, which ensure accuracy, precision and rigor in the measurement, monitoring and verification of emission reductions. ACR provides the flexibility of a wide range of methodologies that diversify offset sourcing options and demonstrate environmental benefits beyond emissions reductions.  

ACR brands the premium verified emissions reductions (VERs) issued against ACR standards as Emission Reduction Tonnes, ERTs. One ERT represents the reduction or removal from the atmosphere equivalent to one metric tonne of carbon dioxide. 

Robust Registry System

ACR also operates a robust and secure electronic registry system, powered by APX, for members to register California and voluntary market projects and record the issuance, transfer and retirement of serialized, project-based and independently verified offsets.

The contracting of offsets for purchase or retirement takes place directly between buyer and seller through over-the-counter (OTC) transactions outside of the Registry system or on an approved, linked offset exchange. After a sale takes place, the counter-parties record the transfer of ownership or retirement of offsets within the Registry.

The use of a fully transparent registry system is fundamental to the credibility of the market. ACR ensures transparency by requiring that project registration and verification documents be made public. We ensure no double counting or double selling by serializing offsets and by linking to online offset issuance and retirement logs. 

Offset Projects

ACR registers offset projects from around the globe from a wide range of project types including:  

    • Afforestation and Reforestation (A/R) of Degraded Lands
    • Improved Forest Management (IFM)
    • Avoided Conversion of Grasslands and Shrublands to Crop Production
    • Compost Additions to Grazed Grasslands
    • Restoration of California Deltaic and Coastal Wetlands
    • Restoration of Degraded Wetlands of the Mississippi Delta
    • Restoration of Pocosin Wetlands
    • Destruction of Ozone Depleting Substances (ODS) and High-GWP Foam
    • Use of Certified Reclaimed HFC Refrigerants and Advanced Refrigeration Systems
    • Transition to Advanced Formulation Blowing Agents in Foam Manufacturing and Use
    • Capturing and Destroying Methane from U.S. Coal and Trona Mines
    • Landfill Gas Destruction and Beneficial Use
    • Methane Recovery in Animal Manure Management Systems
    • Replacement of SF6 with Alternate Cover Gas in the Magnesium Industry
    • Transport / Fleet Efficiency
    • Recycling of Transformer Oil
    • Carbon Capture and Storage
    • Renewable Energy and Energy Efficiency


We welcome collaboration with partners to catalyze new emissions reduction opportunities and enable broader carbon market participation.