Part I of Greenhouse Gas Emissions Monitoring Using Thermal Mass Flow Meters

With increasing pressure from society regarding environmental concerns and international and government mandates concerning greenhouse gas (GHG) emissions, there is a need to provide accurate measurement and monitoring of greenhouse gases. This post discusses greenhouse gas emissions reporting regulations.

New Regulations to Measure Greenhouse Gas

Greenhouse Gas Reporting EPA 40 CFR Part 98
The U.S. EPA mandates that greenhouse gas reporting is required for facilities emitting 25K metric tons or more of GHGs each year per EPA 40 CFR Part 98

Rising levels of GHG and byproducts have been linked to the cause of global warming. Some GHG emissions are created from industrial processes and everyday living habits of the seven billion plus people on our planet.

Industrial nations from all over the world now recognize that climate change issues are associated with global warming. In 1997 the Kyoto Protocol was first adopted, in which many countries committed voluntarily to the reduction of four greenhouse gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), as well as two byproduct gas groups: hydrofluorocarbons and perfluorocarbons. While the United States rejected the Kyoto Protocol, the U.S. Environmental Protection Agency (EPA) has issued strict policies and regulations to reduce greenhouse gas emissions.

When the Kyoto Protocol was ratified, a demand for CERs was created. CERs are more commonly known as carbon credits. A carbon credit is a license for the credit holder to produce one ton of carbon dioxide. Credits are only awarded to those parties or organizations that reduce GHG below a specific quota. Those parties in which lower emissions can sell their credits to gas emission emitters may be countries, large commercial entities, or power generators.

The EPA, responding to the Consolidated Appropriations Act, 2008, released the Mandatory Reporting of Greenhouse Gases Rule (74 FR 56260), which demands owners and operators of United States facilities emitting 25,000 metric tons or more of GHGs each year, to monitor and measure GHGs and report other pertinent information to the EPA. The information is to be used to assist in future policy decisions. This regulation is commonly referred to as 40 CFR Part 98, while its implementation is known as the Greenhouse Gas Reporting Program (GHGRP)

According to the first released data through the program, in 2010, there were over 5,500 U.S. emitters, which meet or exceed the minimum threshold of 25,000 metric tons of CO2e (carbon dioxide equivalent).

Every gas has a different capacity to heat the atmosphere, known as global warming potential (GWP). CO2 has become the standard to which other gases are compared and has a GWP of 1. When GHG data is reported, it is reported as equivalent to CO2 (CO2e or carbon dioxide equivalent).

Greenhouse Gases


Carbon Dioxide (CO2)


Methane (CH4)


Nitrous Oxide (N20)


EPA 40 CFR 98 accuracy requirements for measuring GHGs vary depending on the subpart; however, 5% is typical. Additionally, 40 CFR 98 requires that flow meters be periodically calibrated per manufacturer’s recommendations.

In part II of this series, we discuss the pros and cons of the main mass flow technologies used in greenhouse gas monitoring. Read more.

To read the comprehensive Sage Metering white paper, visit “Greenhouse Gas Emissions Monitoring Using Thermal Mass Flow Meters.”