4.4.3: Environmental Costs to Extraction
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How we extract oil and natural gas today will be covered in more detail later, but we’ll talk about some of the costs now. When we remove material from the earth, there are consequences: Every action has a reaction, every cause has an effect. When we drill we affect systems at depth and at the surface, sometimes disrupting delicate balances and causing dramatic changes to ecosystems.
Less-obvious types of pollution
Some extraction removes vegetation at the surface, exposing dirt and sediments to the elements and allowing them to be easily eroded away. This leads to a type of pollution called turbidity, where the pollution isn’t a chemical, it’s the sediment itself. It clouds the water, causing less sunlight to get through. This affects microscopic organisms that rely on sunlight, and since those organisms are at the very base of the food chain, the ramifications of sediment pollution extend all the way to the top. In addition, the influx of sediment can cause a rapid increase in deposition rates. This means that areas where there isn’t necessarily a lot of sediment settling out of the water might experience a much higher rate, clogging riverbeds or dams, and potentially changing the flow of a river dramatically.
Human induced earthquakes – injection wells
The environmental costs of extracting energy-resources are numerous, with varying degrees of severity. A recent consequence of increased oil and gas activity is human-induced seismicity. These earthquakes range from very small to as large as an earthquake you might expect in California. Although some earthquakes have been associated with oil and gas extraction, the largest earthquakes are usually the result of injection wells (sometimes called disposal wells), wells that are used to dispose of waste waters used in drilling. Injection wells involved much higher pressures than typical extraction wells, and this high pressure can re-activate old faults deep in the crust. Severe damage has been caused in some towns as a result.
Read this article from Forbes on earthquake hazards associated with drilling: Thanks To Fracking, Earthquake Hazards In Parts Of Oklahoma Now Comparable To California.
After reading, think about how you would answer the questions below. Click 'Answers' to see how your thoughts compare to the answers provided.
- Is the increase in earthquake hazard in Oklahoma really due to fracking?
- Compare the map of earthquakes associated with oil and gas with a map of recent earthquakes published by the United State Geological Survey (USGS) – how common does it seem like earthquakes are in Ohio? USGS Oklahoma Earthquakes
- Like most things, this is a little more complicated. Although fracking certainly contributes to the increase in earthquakes in Oklahoma, Dr. Conca notes that the culprit is most likely watewater injection, which changes the pressure systems at depth and can allow for things to move that wouldn't otherwise. Wastewater is created both at fracking sites and at regular drill sites, so there are multiple culprits.
- For the last three years, there have been 585, 890, and 518 earthquakes per year. Seems like earthquakes are pretty common now! But from 1978 to 2008, Oklahoma experienced less than 2 earthquakes a year.
Methane emissions: Legacy Oil and Gas Infrastructure
Sometimes the environmental costs are not apparent until many years later. When it comes to drilling, many states suffer from abandoned oil and gas infrastructure that was neither documented when originally installed, nor plugged/cleaned up when extraction ended. Pennsylvania, home to some of the largest and earliest oil fields, has an estimated 300,000+ orphan and abandoned oil and gas wells, the vast majority of which have unknown locations. Part of the reason so many wells are ‘missing’ is because there were no regulations regarding oil and gas drilling until the 1950s – people didn’t have to report well locations. Because the oil was relatively shallow in Pennsylvania, it was pretty easy to extract. Regular people would drill in their back yards or on their farms, using the oil or gas to heat their homes until it ran out. Similarly, small companies would drill in an area until it ran dry, and then move on, or eventually go bankrupt. Since plugging wasn’t required in the early days of the oil and gas industry, most of these wells serve as conduits from shallow oil and gas fields to the surface. It’s been estimated that nearly 7% of Pennsylvania’s methane emissions are from these legacy wells (Kang et al., 2014, Direct Measurements of methane emissions from abandoned oil and gas wells in Pennsylvania, PNAS, v.111 n.51:18173–18177), and there are some who think that may be an underestimate.
Methane emissions: Plugged Wells
In addition to unplugged wells, plugged wells are also a large contributor to methane emissions. The plug on a well lasts only as long as its weakest component, which in modern plugs is usually the cement. Cement has a lifespan of about 30 years, which means that even if all the wells were plugged, each plug would need to be replaced, or at the very least reassessed, every 30 years – at least until the technology improves.
Want to learn more about orphan and abandoned oil and gas wells? Check out Marcellus Matters and PA Oil and Gas Mapping(link is external). for more information. We are still reliant on fossil fuels, and mining and drilling is the only way to get them. It’s worth remembering that getting them likely has a larger price over time than simply what we pay at the pump.