Shale gas. Natural gas. Tight Sands. Unconventional gases. Conventional gases. Fracking. Hydraulic fracturing.
There are so many terms thrown around in the media today when referencing gas in the energy industry, that for many people, it's become overwhelming to try and figure out what's going on. However, it's important to know the distinctions between different types of gas, how they're extracted, and what the consequences of these methods are.
Natural gases are just that: natural.
They are found in deep underground rock formations, similarly to crude oil and coal. Natural gas can be either conventional or unconventional, depending on the ease of their extraction.
Conventional gas is simply natural gas found in geological formations that make it easier to extract, such as in a gas trap (a pocket of gas underground). They are easily extracted through a well by a simple pump method, or by natural pressure created by the pathway of the well. Think about it as twisting open a soda bottle cap - the bubbles (gas) rise to the top and escape the container.
Unconventional gas refers to natural gas that is much harder to extract, and there are three main types of this gas: Shale gas, Coal-bed methane (CBM), and Tight Sands . These kinds of gases are either buried deep within rocks miles below the surface, or trapped under impermeable rock, that doesn't allow it to be easily extracted without advanced technology or extremely high costs. The only problem is that most of the growth in supply today is found through these unconventional forms.
Because these unconventional gases are difficult to extract, the methods used to get them are often environmentally risky. Let's take shale gas as an example. Hydraulic fracturing (or 'fracking') is needed to extract shale gas. What happens is that water is injected into the ground, which creates pressure and thus cracks in these impermeable rocks. After creating these cracks, the water rises up naturally due to the pressure (think soda bottle again), and the shale gas is able to follow up the same cracks towards the surface to be collected.
There are many issues to this method. First, the water used to be injected are by this time so full of toxic chemicals, that they cannot be released haphazardly. They are kept in man-made ponds to be treated, but the water still poses a danger: back in 2010, hundreds of ducks that took a quick rest on the surface of one of these ponds in Canada died -some even on the same day that they made contact with the water. Another issue is that this water may leak into the ground, contaminating the water we drink. This is what the highly controversial documentary, Gasland, portrays in this short little clip from the film:
Now, bear in mind that the film was highly criticized for misalignment of truths and some downright falsity, but this video just highlights some real concerns that people in the community have with regards to the fracking process.
The last concern is that the abrupt changes in pressure due to injected water could create seismic activity - that's earthquakes in plain English - not to mention loss of vegetation from clearing space for fracking in the first place.
Despite all of these concerns, there are many benefits to extracting unconventional gas, primarily because we rely on them for our basic necessities, such as heating and cooking. It is one of the cheapest energy resources for the consumer, and it does produce less carbon emissions than other sources of energy such as coal.
Whatever issues with the methods or consequences used to extract natural gas , it is clear that unconventional forms of gas may be a large part of our energy future. The world is nervous about peak oil and carbon emissions. Particularly for the U.S., the potential lies for turning the negotiating tables on oil-rich Middle Eastern nations. The speculations on the future of energy is murky, but nonetheless, keep an ear out. Natural gas isn't going to be disappearing any time soon.