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Natural Gas as a Bridge Fuel

Responsible Gas: Managing Methane Emissions in Oil and Gas Operations

With shale gas fundamentally altering the shape of the American energy market and natural gas being promoted as the bridge to a low-carbon future, it’s an important energy source that can’t be wasted.  But until methane emissions are fully measured, monitored, controlled and reduced, the position of natural gas as a greener substitute for coal and oil, which is a large part of its appeal, is open to serious question.

Natural gas’ reputation as the “clean” fossil fuel has been earned because it emits about half of the CO2 and significantly less soot, sulfur and other particulates than coal.  But this ignores the problem of methane – a powerful greenhouse pollutant that has been analyzed to be more than 80 times more potent than CO2 for the first 20 years after it is emitted.

In 2010, researchers at the Massachusetts Institute of Technology encouraged U.S. policymakers to consider the nation’s growing supply of natural gas as a short-term substitute for aging coal-fired power plants. In the results of a two-year study, the researchers said electric utilities and other sectors of the American economy will use more gas through 2050. Under a scenario that envisions a federal policy aimed at cutting greenhouse gas emissions to 50 percent below 2005 levels by 2050, researchers found a substantial role for natural gas.

“Because national energy use is substantially reduced, the share represented by gas is projected to rise from about 20 percent of the current national total to around 40 percent in 2040,” said the MIT researchers. When used to fire a power plant, gas emits about half of the carbon dioxide emissions as conventional coal plants.

The report, titled “The Future of Natural Gas,” acknowledges that U.S. energy and climate policy is in flux. For the most part, the MIT researchers accept the idea that the advancement of onshore gas drilling technology has set the stage for a gas boom in the United States. As such, the MIT researchers analyze increasing gas consumption under a number of different scenarios.

Gas is an option for cutting power plant emissions and addressing global warming in the short term. But the researchers warned that the gas cushion shouldn’t distract policymakers from addressing the need for nuclear power and carbon capture and sequestration (CCS) technology for coal-fired generation.
“Though gas frequently is touted as a ‘bridge’ to the future, continuing effort is needed to prepare for that future, lest the gift of greater domestic gas resources turn out to be a bridge with no landing point on the far bank,” the report says. “Barriers to the expansion of nuclear power or coal and/or gas generation with CCS must be resolved over the next few decades so they are capable of expanding to replace natural gas in generation.”

Other elements including, energy efficiency, alternate energy sources, re-forestation and carbon capture, utilization and sequestration should also be part of the global climate change approach.

Carbon capture, utilization and storage (CCUS), also referred to as carbon capture, utilization and sequestration, is a process that captures carbon dioxide emissions from sources like coal-fired power plants and either reuses or stores it so it will not enter the atmosphere. Carbon dioxide storage in geologic formations includes oil and gas reservoirs, un-mineable coal seams and deep saline reservoirs — structures that have stored crude oil, natural gas, brine and carbon dioxide over millions of years.