A study from the U.S. Department of Energy (DOE) said that emissions from natural gas would mostly come from fuel combustion and not from resource extraction, such as hydraulic fracturing and horizontal drilling.

The report, “Role of Alternative Energy Sources: Natural Gas Power Technology Assessment,” was prepared by the Office of Fossil Energy’s National Energy Technology Laboratory (NETL).  Analysts focused on seven criteria to evaluate the role of natural gas in the U.S. energy supply chain: resource base, growth, environmental profile, cost profile, barriers, implementation risks, and expert opinion from stakeholders in academia, government, and private industry. Four natural gas power technologies were evaluated: combined cycle, combined cycle with carbon capture and sequestration, simple cycle, and the U.S. fleet baseload average.

The U.S. resource base for natural gas has shown recent growth that is expected to continue because of the expanded extraction potential of various shale gases, such as horizontal drilling and hydraulic fracturing. The growth in natural gas supply may be hindered by the possibility of surface water deterioration and legislative uncertainty. However, property engineered and implemented natural gas systems have favorable environmental and cost profiles in comparison to other energy sources, the report said.

The development of shale gas and other unconventional natural gas wells requires the use of technologies that could release higher levels of methane, a greenhouse gas (GHG), than do conventional well technologies. However, power plant GHG emissions far outweigh those of natural gas extraction and transport, and improvements to policy and technology could reduce these upstream burdens, according to the report. The current U.S. fleet of baseload natural gas power plants running on the domestic profile of natural gas has lifecycle GHG emissions of 514 kilograms of CO₂ equivalent per megawatt-hour. If switched to an unconventional mix of natural gas, the lifecycle emissions of baseload power increase to 520 kilograms of CO₂ equivalent per megawatt-hour, an increase of only 1 percent. In addition to GHG emissions, the report also inventories other air emissions, water use and quality, and resource consumption.

The report said price volatility of natural gas is due to supply uncertainty driven by natural and economic variables. At a natural gas price of $5 per million Btu , the cost of electricity delivered by a new natural gas combined-cycle power plant is $53.40 per megawatt-hour. The report also includes the cost of electricity from other natural gas power systems, including simple-cycle gas turbines and power plants with carbon capture, and evaluates the cost uncertainty caused by natural gas price volatility and capital cost contingencies.

To read the full report, click here.

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