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By the time oil and natural gas reach consumers, they have been processed to remove both unwanted materials and usable petroleum products. Extracting oil and gas, however, leads to dramatic impacts on the landscape, air, and water -- well before the global climate impacts of burning fossil fuels are felt.
How are oil and gas extracted?
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| Cow crushed by inadequately fenced pumpjack. |
The techniques used to remove oil and gas from the ground vary depending on the nature of the formation being exploited and include:
- Conventional drilling involves the use of muds to keep the drill bit cool and lift the rock cuttings out of the hole.
- Hydraulic fracturing, or “fracking,” stimulates oil and gas wells by pumping hundreds of thousands of gallons of fluids and sand into the oil or gas formation, eventually cracking open the formation.
- Coalbed methane (CBM) recovery seeks to exploit the presence of methane (natural gas) often found loosely bound to coal deposits by water pressure -- by pumping the water out of a coal bed, the methane is detached from the coal and flows up the well.
Where are oil and gas found?
Oil and gas development continues to be a thriving industry due to higher prices and improved technology, and significant deposits are found throughout the world. In the U.S., it has been common to see development in states such as Alaska, Texas, Colorado and Wyoming. However, areas that were once considered not economically viable -- such as Ohio and Arkansas -- are now experiencing a boom in development.
Why are oil and gas dirty?
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The impacts to human health and the environment from oil and gas development are numerous. Oil and gas wastes and by-products contaminate the air, soil, and water at numerous stages in the extraction process, including:
- The drilling process: Releases of drilling muds and additives to the environment can occur at the well site, while mud injected underground can move through formations and contaminate surface or groundwaters.
- Hydraulic fracturing: The fluids used in fracking can pollute or alter groundwater in numerous ways -- by direct injection into aquifers, by migration underground (aided by the fracturing of underground formations), or by above ground spills at the well site.
- Coalbed methane development: The water withdrawn from coal beds often brings other pollutants along with the methane, which leak into ground and surface waters -- not all of the injected water returns to the surface, and the water that does is often re-injected into the ground for disposal. In addition to polluted drinking water, a further impact of CBM development is the build-up of explosive levels of hydrogen sulfide and methane under buildings and inside homes.
- Waste pits: A significant portion of the chemicals injected underground during drilling, hydraulic fracturing or well maintenance return to the surface. On the surface, they are at least temporarily stored in open pits or tanks. These pits are not always lined, and can leak into ground and surface waters, while volatile components -- such as benzene -- can evaporate into the air.
- Spills: Spills and leaks of raw chemicals, or oil and gas wastes, may affect land, water, and air. Recorded spills have released pollutants such as crude oil, contaminated water, diesel fuel, glycol, and oil and fluids used in drilling and fracking.
- Releases into the air: In addition to leaks and venting of natural gas and other hazards, the fluids and machinery used for extraction and processing can release toxics into the atmosphere. Noise pollution is another by-product of oil and gas development and can have physiological effects on humans and wildlife, in addition to further driving down land values and quality of life.
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Dirty Energy 
