Fuel Switching

Natural gas is the cleanest of the fossil fuels, with the lowest GHG emissions per unit of energy, emitting about half of the CO2 of coal when burned for electricity generation, as well as generally lower emissions of other pollutants. Shifting electric generation from coal to natural gas could significantly reduce emissions. Such a shift would be useful but would not by itself reduce emissions sufficiently for a low-emissions future to minimize climate change. Thus, natural gas is more likely to be a bridge than a final solution. Additionally, the feasibility of natural gas as a bridge fuel will depend on the stringency of any emissions-limiting policies that are adopted.

Until recently, resources of natural gas were thought too small to support a transition. Recent improvements in technology have made economic unconventional gas resources, such as shale, leading to higher resource estimates. If these estimates are confirmed, natural gas could be a long-term option. However, there is some concern that shale gas development may have negative impacts on the local freshwater resources and land resources (DOE, 2009a). Another possible future source is natural gas hydrates found on the ocean floor, which are estimated to contain from one to a hundred times the world resource of conventional natural gas. Methods for recovery of hydrates are under investigation, but it is unlikely that hydrates would contribute significantly to the production of natural gas in the near term without major breakthroughs in the recovery process (NRC, 2010h).

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