Environmental impact of the energy industry to virtually all aspects of present society, especially for transportation and heating for both homes and for commercial activities. Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil., and far fewer pollutants than other fossil fuels. However, in absolute terms it does contribute substantially to global carbon emissions, and this contribution is projected to grow. According to the IPCC Fourth Assessment Report, in 2004 natural gas produced about 5,300 Mt/yr of CO emissions, while coal and oil produced 10,600 and 10,200 respectively (Figure 4.4); but by 2030,
Environmental impact of hydraulic fracturing life cycle of oil or coal. Until recently, Canadian provinces such as Alberta, Saskatchewan, and Nova Scotia produced over half of their electricity from coal combustion whereas Ontario has already completely phased out coal-powered electricity. Switching from coal- to natural gas-powered electricity can reduce carbon dioxide emissions by ~50% and also decrease the amount of NOx and SOx emitted to atmosphere. Lack of baseline data or before-and-after hydraulic fracturing sample collection and analysis makes it challenging to quantify environmental impacts (if any) resulting from hydraulic fracturing. Hydraulic fracturing fluids include proppants and other substances, which may include toxic chemicals. In