fossil fuel use is the primary source of CO2 emissions¹. It is also not particularly surprising to learn that burning fossil fuels is damaging to air quality and as such brings about a number of health effects including impaired lung function, shortness of breath, wheezing, asthma attacks and premature death². But it might be a surprise to hear that not all fossil fuels pollute the environment or damage our health in the same way.
While often bundled up together, fossil fuels are made up of coal, oil and natural gas. All can provide energy but at a different cost – both financial and environmental. Given that natural gas is available only as part of fixed and existing reserves, it is by definition considered a fossil fuel. Indeed, natural gas was made in a similar way to oil and coal: millions years ago, the remains of plants and animals were buried in layers of soil, this was often mixed with sand and silt. Given current levels of use, it is estimated that the natural gas reserves will last for another 35 years or so³.
But that does not negate the fact that natural gas is also different in many ways to coal and oil. For example, natural gas is a highly efficient fuel: about 90 percent of the natural gas produced is delivered to customers as useful energy. In contrast, only about 30 percent of the energy converted to electricity in conventional generating facilities reaches consumers⁴.
At the same time, the difference in terms of climate change and environmental impact between natural gas and other fossil fuels is such that natural gas is considered as a key energy source enabling a transition to a low carbon and renewable energy future.
Natural gas is trapped underground in reservoirs; it is a mixture of several gases including methane, ethane, propane and butane. The good news is that it burns completely and leaves no ashes which means that is it one of cleanest fossil fuels³. The data suggests that burning natural gas results in fewer emissions of nearly all types of air pollutants while in terms of carbon dioxide, natural gas emits 117 pounds per million British thermal units (Btu) while coal emits 200 pounds and oil 160 pounds⁵.
Because of its low emissions both in terms of climate change and air pollution, it is considered that natural gas can help us meet our energy needs in the short and medium term, while building up technology and capacity for the deployment of renewable energy. This is particularly important given the need to reduce greenhouse gas emissions now while at the same time addressing issues such as acid rain, smog and particulate matter.
In addition to these distinct environmental benefits, natural gas can also be turned into a liquid form, called liquid natural gas which is not only much cleaner than any other fossil fuels, but it takes up much less space compared to the gaseous form.
But it is not all good news. As with fossil fuels in general, there are issues involved with the extraction of natural gas. Natural gas deposits are usually located a few hundred metres from the surface so to access it companies need to drill it out. But due to the way in which natural gas is formed, it is not found in open pockets but rather trapped in rock formations that can stretch for long distances underground⁵,⁶. This means that to extract natural gas, the process of “hydraulic fracturing” is needed which can not only cause small earthquakes and tremors but also often requires the use of chemicals which are pumped into the ground; this contaminates water sources.
So in reality, while natural gas seems to offer a lot of advantages compared to other sources of fossil fuels, the underlying concerns that hold true for fossil fuels also come into play when considering the use of natural gas. These are the finite supply of natural gas as well as the environmental concerns linked to the extraction of natural gas. While natural gas can be considered an energy source that could help bridge the gap between today’s renewable technology until it can be fully deployed, there is also a possibility that such a policy would divert important investments away from renewables and into technologies that mitigate the effects of natural gas extraction and use.