Natural gas has some advantages over other fossil fuel energy sources, such as coal. It's cleaner burning and has a lower carbon footprint. However, relying heavily on natural gas is also problematic for several reasons.
Air pollution and climate change
Natural gas-fired power plants do emit lower levels of sulphur dioxide and nitrogen oxides than coal-fired plants, but these emissions still contribute to acid rain and ground-level ozone, both of which can damage forests and agricultural crops.
Ground-level ozone (commonly called smog) has also been linked to a range of respiratory illnesses. More recently, ground-level ozone has been linked to the development of childhood asthma, the "most common chronic disease" among children.
Possibly more troubling are the emissions of fine particulates from gas-fired power plants. Though particulate emissions are about ten per cent of those produced by coal power, the U.S. Environmental Protection Agency estimates that 77 per cent of particulates from natural gas plants are dangerously small. These fine particulates have the greatest impact on human health because they by-pass our bodies' natural respiratory filters and end up deep in the lungs. In fact, many studies have found no safe limit for exposure to these substances.
Natural gas also contributes to climate change. Burning natural gas produces fewer greenhouse gas emissions (25 to 40 per cent lower per unit of generated electricity) than coal or oil, but there will be no real climate change benefit until gas-fired power plants actually displace coal-fired generation. Across North America, gas-fired plants continue to be built in addition to coal-fired power.
Using natural gas as a "transition fuel" also poses risks. That's because pipelines required to transport natural gas from its source to the power plant are expensive. High pipeline costs have to be spread out by building several gas-fired power plants that last a generation. Even the best-case scenario shows that natural gas is not a solution to climate change.
Hydraulic fracturing, or "fracking", is the act of injecting pressurized water, sand and chemicals into a rock formation, resulting in a fracture where natural gas can be extracted. This method has become increasingly common and its rapid deployment raises serious concerns about the impact on freshwater resources. Fracking requires large volumes of water (8-15 million litres to drill each well) and is of particular concern to drier regions. Other environmental concerns include the composition of the fracking fluids, storage and disposal of wastewater, and the possible migration of gas into water supplies.