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State and trends


Fracking techniques have raised concerns over the potential for increased methane emissions from the oil and gas sector (US EPA 2014). Recent research indicates that methane leaks from natural gas production and transportation may offset the benefits of greenhouse gas reductions from natural gas electrical generation compared with coal-fired generation, despite lower GHG emissions from natural gas (Howarth et al. 2011; Miller et al. 2013; De Gouw et al. 2014; Petron, et al. 2014; Brandt et al. 2014). The integrity of some retired oil and gas wells has also been called into question and may be sources of errant methane releases (Jackson 2014). Research has indicated that, for specific areas in the US, the range of increase of methane from unconventional development may be as high as 6.2–10.1 per cent (Schneising et al. 2014). In the United States, draft regulations have recently been issued to require monitoring and reduction of these emmissions (US EPA 2015).


2.9.3 Secondary resources


Traditionally, coal deposits in the US supplied the fuel for generating electricity, though coal production and use is now shrinking. Electricity generation from natural gas and renewable sources have increased in the United States to fill the gap created by decreasing coal-fired generation (US EIA 2016a). In 2014, approximately 38 per cent of electrical generation came from coal, 27 per cent from natural gas, 19 per cent from nuclear and 13 per cent from renewables (US EIA 2016g). In contrast, Canada produces over 60 per cent of its national electricity from renewable hydroelectric resources. Nuclear resources provide approximately 13 per cent, conventional steam provides 14 per cent, combustion turbines produce 7 per cent, with the remainder coming from renewable resources (Statistics Canada 2012). Thus, the Canadian electrical sector is largely decarbonized. Despite differences in supply, the two countries share some trends: electricity generation from renewable sources and natural gas is increasing. Large investments in the natural gas generating sector have come at a time when a slowing in the growth of demand for electrical power is seen across developed countries and production from renewables has increased (US EIA 2015).


Roads and natural gas well-pads crisscross the Pinedale Anticline gasfield, just outside of Pinedale, Wyoming, US © Rogers 2015


In the US, the two traditional forms of electric generation that emit no GHGs–hydroelectric and nuclear—have had relatively stable output since 2001 (US EIA 2016b; 2016d). Large shifts have occurred in two forms, coal and natural gas. Coal generation has fallen by almost 25 per cent (US EIA 2016c), while natural gas generation has increased by over 50 per cent (US EIA 2016e). Despite the lack of change in hydroelectric and nuclear, the change in the mix of coal and natural gas is significant. Natural gas fired generation emits lower GHG emissions per unit of electricity than coal. Therefore, the change from coal to natural gas in the US, along with increased renewable deployment and efficiency has contributed to lowered GHG emissions from electricity generation (US EIA 2014). In Canada, increases in nuclear and hydroelectric power generation of 22 per cent and 6 per cent occurred between 2000 and 2012 (US EIA 2016f). Total fossil fuel generation during this period fell slightly, by approximately 16 per cent (US EIA 2016f).


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