Rhode Island Greenhouse Gas Inventory

A greenhouse gas (GHG) is any gas that can trap heat from Earth’s surface and reradiate it back down to Earth’s surface. Water vapor is the most the most prevalent GHG, while carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) are the most common anthropogenic (human influenced) GHGs.

A GHG inventory is a historical account of the quantity of GHGs emitted to, or removed from, the atmosphere over a specific period (e.g., one year) from all sectors of the economy. GHG inventories are used to develop strategies for emissions reductions and to track progress of implemented policies.

The Act on Climate was signed into law by Governor McKee in 2021, which requires mandatory, enforceable, GHG emissions reduction mandates in 2020, 2030, 2040, and net-zero emissions by 2050. DEM’s annual Rhode Island Greenhouse Gas Inventory is the primary scientific tool used by the Executive Climate Change Coordinating Council (EC4) to assess the state’s progress towards the Act.

DEM updates Rhode Island’s GHG inventory annually. Since federal, state, and local government must gather very large quantities of data, GHG inventories typically lag 2+ years behind the current year. DEM is working to shorten this delay to provide the most up-to-date information to assess the state’s progress towards the Act on Climate more promptly.

Rhode Island’s GHG inventory details economy-wide sources and sinks of emissions back to 1990, which is the “baseline” year identified by the Act on Climate. Methodologies are kept relatively consistent across the timeseries to maintain an accurate depiction of how emissions change.

The most common anthropogenic GHGs, including carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), are estimated. Fluorinated gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆), and nitrogen trifluoride (NF₃) are also covered. Emissions from all GHGs are converted to a common unit, million metric tons carbon dioxide equivalent (MMTCO₂e) based on each GHG’s global warming potential. 

DEM converts GHGs to MMTCO₂e with the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5) 100-year global warming potentials (GWPs). Learn more about GWPs.

Rhode Island’s GHG inventory follows the key categories identified by the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and its refinements. Many U.S. states that compile their own GHG inventories also follow this approach, which provides a just comparison across state lines.

Energy

• Transportation (aviation, highway vehicles, and non-road sources)
• Electricity Consumption
• Residential Heating
• Commercial Heating
• Industrial Heating
• Natural Gas Distribution

Industrial Processes and Product Use

• Mineral Industry
• Metal Industry
• Electronics Industry
• Product Use

Agriculture

• Livestock
• Soil Management

Waste

• Solid Waste Disposal
• Wastewater Treatment and Discharge

Natural and Working Lands

• Forest Land
• Cropland
• Grassland
• Wetlands
• Settlements 

DEM obtains robust, state-level data to estimate GHG from a range of sources. The EPA’s State Inventory Tool (SIT) contains the latest state-level fuel consumption data from the Energy Information Administration’s (EIA) State Energy Data System (SEDS). Data from EIA, the New England Power Pool Generation Information System and ISO New England are used to estimate emissions from electricity consumption. DEM also obtains local data from intra-departmental sources including the Division of Agriculture & Forest Environment and the Office of Water Resources.

The EC4’s 2022 Rhode Island Climate Update defined net-zero emissions for purposes of the state’s compliance with the Act on Climate:

‘Net-Zero’ refers to the requirement that the summary measure of greenhouse gas emissions emitted over the course of a calendar year less the summary measure of greenhouse gas emissions absorbed or otherwise broken down over the course of a calendar year equals zero.

Electricity consumption is the only inventory sector to include emissions from outside of Rhode Island’s geographic borders. This deviation from international GHG accounting conventions was endorsed by the EC4 on May 11, 2016 to include the effects of Rhode Island’s Renewable Energy Standard (R.I. General Laws § 39-26-4). Renewable energy certificates (RECs) that are settled in Rhode Island offset a portion of the state’s electric demand. Emissions are attributed to the state’s electric demand that is not offset by RECs with a mixture of natural gas, petroleum, and coal from the ISO New England electric grid. Learn more about differences between electricity consumption vs. electricity generation GHG accounting.

• Proposed Methodology Improvements for the 1990 Baseline
  • Public Listening Session Presentation
  • Public Listening Session Recording
• Updates to Electricity Sector GHG Accounting
• Accounting Carbon Sequestration from LULUCF
• Electricity Generation vs. Consumption Accounting
  • EC4 Endorsement of Electricity Consumption Accounting

• 2021 Act on Climate
• EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks
• EPA Facility Level GHG Emissions Data (FLIGHT)
• Energy Information Administration (EIA) State Profile
• U.S. Climate Alliance