Corporate Banner
Satellite Banner
Environmental Analysis
Scientific Community
Become a Member | Sign in
Home>News>This Article

How to Count Methane Emissions

Published: Tuesday, April 29, 2014
Last Updated: Tuesday, April 29, 2014
Bookmark and Share
Study provides new metric for comparing the greenhouse gases methane and carbon dioxide.

In formulating policies to address greenhouse gas emissions, or evaluating the potential impact of different energy technologies on global climate change, one of the thorniest issues is how to account for the very distinctive characteristics of various different gases.

For example, methane is a potent greenhouse gas, as well as a significant byproduct of using natural gas - advocated by many as a “bridge” to a lower-emissions future. But a direct comparison between methane and carbon dioxide, the most abundant greenhouse gas emitted by human activities, is complicated: While the standard figure used for emissions trading and technology evaluation says that, gram for gram, methane is about 30 times as potent a greenhouse gas as CO2, scientists say that’s an oversimplification.

As reported in a paper published in the journal Nature Climate Change, authored by MIT assistant professor of engineering systems Jessika Trancik and doctoral student Morgan Edwards, this conversion factor (called the global warming potential, or GWP) may significantly misvalue methane. Getting this conversion factor right is challenging because methane’s initial impact is much greater than that of CO2 - by about 100 times.

But methane only stays in the atmosphere for a matter of decades, while CO2 sticks around for centuries. The result: After six or seven decades, the impact of the two gases is about equal, and from then on methane’s relative role continues to decline.

Static measures, such as the GWP, give a false sense of the gases’ impacts, and could lead to unintended climate outcomes when used as the basis for policies and planning, Trancik says. Instead, she and Edwards argue for the use of what they call “dynamic metrics,” which lead to a conversion factor that changes over time in a predictable way.

“With CO2, one cares about the cumulative emissions,” Trancik says. “But with methane, the timing of emissions matters.” The issue for regulators and planners, she says, is: “How can we take emissions timing into account, in a metric equation that is simple and predictive enough to be used?”

The authors develop a kind of metric that incorporates limited information about the future - an intended “stabilization level” for the Earth’s climate - but doesn’t require knowledge about the exact climate scenario to be followed. The researchers develop two such metrics, the instantaneous climate impact (ICI) and the cumulative climate impact (CCI); the latter is more conservative in earlier years.

The paper shows that the choice of how to quantify the effect of methane versus CO2 can have a bigger effect on the ultimate climate outcomes than uncertainties in how much leakage of methane occurs in the natural gas production system, which has recently drawn much more attention from researchers and policymakers. For this reason it is important to choose an accurate metric, and understand its properties.

“Any equivalency metric is going to be imperfect,” Trancik says, “which is why it is important to test metrics and understand their properties.” But using a measure that accounts for significant changes to the climate over time should allow for more realistic assessments of the effects of policy decisions - such as in setting environmental regulations, or deciding where to focus research investment.

While it is generally assumed that the climate impact of natural gas to produce electricity is approximately half that of coal, she says, that comparison depends on timing: The figure is true today, but within three decades, compared with coal-fired power plants, the advantage of natural gas is roughly halved under common stabilization goals. Similarly, compressed natural gas as a transportation fuel actually ends up being worse than gasoline within a couple of decades, the authors report.

In the case of natural gas, it’s not the emissions from the plants burning the gas that produce methane; rather, it is the leakage of methane - the main component of natural gas - during drilling and transportation of the fuel. So there is potential to reduce the impact of natural gas by investing in better control of such leakage, Trancik says.

More accurate comparisons of the effects of methane and CO2 can also be important when evaluating technologies that produce emissions of more than one type of gas. For example, the study found that algae-based biofuels that incorporate a biodigester may leak enough methane to outweigh the emissions benefits over corn ethanol - a consideration that may weigh on decisions about which technology designs should be invested in and how they should be regulated, she says.

Further Information

Join For Free

Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 3,500+ scientific posters on ePosters
  • More than 5,100+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Achieving “Green” Desalination
Workshop explores ways to reduce or eliminate the carbon footprint of seawater desalination plants.
Thursday, October 20, 2016
Changing Ocean Chemistry Due To Human Activity
More anthropogenic carbon in the northeast Pacific means weaker shells for many marine species.
Wednesday, September 07, 2016
Wireless, Wearable Toxic-Gas Detector
Inexpensive sensors could be worn by soldiers to detect hazardous chemical agents.
Friday, July 01, 2016
MIT Study: Carbon Tax Needed to Cut Fossil Fuel Consumption
Researchers at MIT have suggested that the technology-driven cost reductions in fossil fuels will lead the world to continue using all the oil, gas, and coal, unless governments pass new taxes on carbon emissions.
Thursday, February 25, 2016
Living a “Mixotrophic” Lifestyle
Some tiny plankton may have big effect on ocean’s carbon storage.
Tuesday, February 02, 2016
Global Reductions in Mercury Emissions Should Lead to Billions in Economic Benefits for U.S.
Benefits from international regulations may double those of domestic policy.
Monday, January 04, 2016
“Kill Switches” Shut Down Engineered Bacteria
Synthetic biology technique could make it safer to put engineered microbes to work outside of the lab.
Monday, December 14, 2015
Shocking New Way to Get the Salt Out
MIT team invents efficient shockwave-based process for desalination of water.
Thursday, December 03, 2015
Game for Climate Adaptation
MIT-led project shows a new method to help communities manage climate risks.
Friday, November 06, 2015
Messing With The Monsoon
Manmade aerosols can alter rainfall in the world’s most populous region.
Friday, October 02, 2015
Intensity of Desert Storms May Affect Ocean Phytoplankton
MIT study finds phytoplankton are extremely sensitive to changing levels of desert dust.
Tuesday, September 01, 2015
Better Estimates of Worldwide Mercury Pollution
New findings show Asia produces twice as much mercury emissions as previously thought.
Thursday, August 13, 2015
Real-Time Data for Cancer Therapy
Biochemical sensor implanted at initial biopsy could allow doctors to better monitor and adjust cancer treatments.
Thursday, August 06, 2015
Nanoparticles Can Clean Up Environmental Pollutants
Researchers have found that nanomaterials and UV light can “trap” chemicals for easy removal from soil and water.
Thursday, July 23, 2015
New Detector Sniffs Out Origins Of Methane
Instrument identifies methane’s origins in mines, deep-sea vents, and cows.
Friday, March 06, 2015
Scientific News
Achieving “Green” Desalination
Workshop explores ways to reduce or eliminate the carbon footprint of seawater desalination plants.
Adapt, Move or Die in Coral Reefs
As oceans warm, coral reef fish might prefer to move rather than adapt, research suggests.
Desalinated Sea Water Linked to Iodine Deficiency Disorders
Study suggests that desalination can dramatically increase the prevalence of inadequate iodine intake.
Reclaim from the Drain - The Importance of Water Reuse
This infographic explains the importance of reusing water to meet the world's increasing water demand.
Carbon Dioxide Levels Pass Troubling Milestone
Carbon dioxide levels are not set to fall below 400ppm for the first time since the Ice Age.
Ice Cores Reveal Decline in Atmospheric Oxygen Over Last 800,000 Years
Researchers have compiled decades of data to produce a record of atmospheric oxygen concentrations.
Ocean Plastic Pollution Worse Than Expected
The Ocean Cleanup concludes first-ever reconnaissance flight over ‘Great Pacific Garbage Patch’.
3D-Printing in Science: Conference Co-Staged with LABVOLUTION
LABVOLUTION 2017 will have an added highlight of a simultaneous conference, "3D-Printing in Science".
Pinpointing Sources of Water Contamination
Lab develops better method of environmental monitoring using the PhyloChip, finds surprising results in Russian River watershed.
Antibiotic Resistant Bacteria In America's Water System
Antibiotic resistant bacteria live inside drinking water distribution systems blamed for rising healthcare costs.
Scroll Up
Scroll Down

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
3,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
5,100+ scientific videos