Alternative fossil fuel sources, such as oil sands, shale gas, and coalbed methane, come with three major drawbacks: they release significantly more greenhouse gases than conventional fuels, they consume and contaminate enormous volumes of water, and they cause serious harm to local ecosystems and human health. These tradeoffs matter because unconventional reserves are vast, potentially quadrupling global oil supplies, and governments and energy companies are actively expanding their extraction.
Unlike conventional oil and gas, which sit in accessible underground reservoirs, unconventional fossil fuels are spread across wide geologic formations and require aggressive techniques to extract. That includes hydraulic fracturing (fracking) for shale gas, strip mining for oil sands, and specialized drilling for tight gas and coalbed methane. Each method amplifies the environmental and health costs of fossil fuel production in ways conventional drilling does not.
1. Higher Greenhouse Gas Emissions
The single biggest drawback of unconventional fossil fuels is their outsized carbon footprint. Extracting, processing, and refining these fuels demands far more energy than pulling conventional crude or gas from a traditional well, and that extra energy translates directly into extra emissions.
Gasoline and diesel refined from Canadian oil sands release roughly 20 percent more carbon over their lifetime than fuel from conventional U.S. crude, according to a joint study by Argonne National Laboratory, UC Davis, and Stanford University. Depending on the specific extraction and refining methods used, that figure ranges from 8 to 24 percent higher. The reason is straightforward: oil sands are a thick mixture of about 83 percent sand, 10 percent bitumen, 4 percent water, and 3 percent clay. Separating usable oil from that mixture requires heating it with steam or mining it in open pits, both of which burn large amounts of natural gas before a single drop of fuel reaches a car.
Shale gas carries its own emissions problem. Hydraulic fracturing releases methane, a greenhouse gas roughly 80 times more potent than carbon dioxide over a 20-year window, directly into the atmosphere during drilling and transport. Research published in Environmental Science & Technology found that keeping methane leakage below 2.4 to 3.2 percent of total production is critical for shale gas to offer any climate advantage over coal. U.S. shale fields have consistently shown higher leakage rates than conventional dry gas operations, undermining the argument that natural gas is a cleaner “bridge fuel” to renewables.
2. Massive Water Use and Contamination
Unconventional extraction is extraordinarily water-intensive, and the water that comes back out is often too contaminated to reuse safely. This creates problems in two directions: it strains local freshwater supplies, and it generates toxic waste that is difficult to dispose of.
A single hydraulically fractured well requires between 1.5 million and 16 million gallons of water, according to the U.S. Geological Survey. To put that in perspective, the high end of that range is enough to fill about 24 Olympic swimming pools for one well. In regions where hundreds or thousands of wells operate simultaneously, the cumulative demand competes directly with agriculture, municipal water systems, and natural waterways.
The water pumped underground during fracking is mixed with sand and a cocktail of chemical additives designed to crack rock formations open. When that fluid returns to the surface as wastewater, it carries those injected chemicals along with naturally occurring substances picked up underground, including heavy metals and radioactive materials. The National Institute of Environmental Health Sciences identifies water quality as a primary concern because these fluids can enter drinking water supplies through well casing failures, surface spills, or improper wastewater disposal. Oil sands mining presents a parallel problem: the process generates vast tailings ponds filled with contaminated water that sit on the landscape for decades.
3. Ecosystem Destruction and Health Harm
Land and Biodiversity Loss
Oil sands extraction is particularly devastating to landscapes. Alberta’s oil sands sit beneath roughly 55,000 square miles of Canada’s boreal forest, one of the largest intact forest ecosystems on the planet. Surface mining strips away everything, including trees, soil, and wetlands, to access the bitumen deposits below. By 2012, over 138,000 acres had been actively disturbed for mine and plant operations.
The energy industry is required to reclaim mined land, but the track record is dismal. As of recent reporting, only a single parcel of land in Alberta has been officially certified as reclaimed and returned to the province. That certification, granted in 2008, was based on an older, less stringent standard requiring just 8 inches of reclamation material. The boreal forest took thousands of years to develop its complex layers of peat, soil organisms, and interdependent plant and animal communities. Recreating that from a sand pit is a challenge no one has demonstrated at scale.
Human Health Effects
Communities near unconventional drilling sites face a well-documented list of health risks. The chemicals used in fracking, along with compounds that surface with the extracted gas, degrade local air quality. Hazardous air pollutants have been detected near development sites at levels exceeding health-based safety standards.
The health consequences show up across age groups. A study of nearly 24,000 primary care patients in Pennsylvania linked proximity to unconventional gas wells with nasal and sinus symptoms, migraine headaches, and chronic fatigue. A separate study of over 35,000 asthma patients in the same state found that living near active wells increased the chance of mild, moderate, and severe asthma flare-ups. Research on older adults found that those living near or downwind of drilling sites had a higher risk of premature death, while a study published in JAMA Internal Medicine documented increased hospitalization for heart attacks among middle-aged and older residents of counties overlying the Marcellus Shale.
Children and pregnant women appear especially vulnerable. Children who lived within 2 kilometers of at least one unconventional well at birth had nearly twice the chance of developing acute lymphoblastic leukemia, the most common childhood cancer. Pregnant women near active wells faced a greater chance of delivering low birth weight babies, and a 2018 study of women near fracking sites in Texas found elevated risk of extreme preterm birth.
Why These Drawbacks Persist
The core issue is economics. Unconventional fossil fuels exist in enormous quantities, and when conventional oil and gas prices rise, extracting them becomes profitable enough to justify the investment. Including oil shale, tar sands, extra heavy oil, and natural bitumen, global oil reserves jump to four times the size of conventional reserves alone. That scale creates powerful financial incentives to keep expanding production, even as the environmental and health costs mount.
Each of the three drawbacks compounds the others. Higher energy requirements for extraction mean more emissions and more water use. More water use means more contaminated wastewater. More land disturbance means less natural habitat to buffer nearby communities from air and water pollution. Unlike a single environmental problem that might be solved with better technology, these drawbacks are built into the physics and chemistry of pulling fuel from difficult geologic formations. Reducing one often intensifies another.