Still, U. Continued strengthening of clean car and fuel economy standards remains critical for reducing oil consumption. On the production side, the United States has experienced a decadelong upswing. Production growth is due in large part to improvements in horizontal drilling and hydraulic fracturing, technologies that have created a boom in U. While horizontal drilling enables producers to drill down and outward—thus reaching more oil or gas from a single well—hydraulic fracturing also known as fracking is designed to extract oil or natural gas from unyielding rock, including shale and other formations.
Fracking involves blasting huge quantities of water mixed with chemicals and sand deep into a well, at pressures high enough to fracture rock and enable the oil or gas to escape.
This controversial method of extraction creates a host of environmental and health problems, including air and water pollution. Coal is a solid, carbon-heavy rock that comes in four main varieties differentiated largely by carbon content: lignite, sub-bituminous, bituminous, and anthracite. Nearly all of the coal burned in the United States is sub-bituminous or bituminous.
Found in abundance in states including Wyoming, West Virginia, Kentucky, and Pennsylvania, these coal types are middle of the pack in terms of carbon content and the heat energy they can produce.
Regardless of variety, however, all coal is dirty. Coal is extracted via two methods: Underground mining uses heavy machinery to cut coal from deep underground deposits, while surface mining also known as strip mining removes entire layers of soil and rock to access coal deposits below. Strip mining accounts for about two-thirds of coal sourced in the United States. Although both forms of mining are detrimental to the environment, strip mining is particularly destructive , uprooting and polluting entire ecosystems.
Coal and the power plants that burn it account for less than a third of U. Cleaner, cheaper alternatives—including natural gas, renewables like solar and wind, and energy-efficient technologies—make coal far less economically attractive.
Future demand for coal is expected to remain flat or to fall as market forces propel alternative energy sources forward. Conventional natural gas is located in porous and permeable rock beds or mixed into oil reservoirs and can be accessed via standard drilling.
Unconventional natural gas is essentially any form of gas that is too difficult or expensive to extract via regular drilling, requiring a special stimulation technique, such as fracking. Abundant in the United States, natural gas covers nearly 30 percent of U. Forecasts suggest it will become an even greater part of the U. Unearthing, processing, and moving underground oil, gas, and coal deposits take an enormous toll on our landscapes and ecosystems.
The fossil fuel industry leases vast stretches of land for infrastructure such as wells, pipelines, access roads, as well as facilities for processing, waste storage, and waste disposal. In the case of strip mining, entire swaths of terrain —including forests and whole mountaintops —are scraped and blasted away to expose underground coal or oil.
Even after operations cease, the nutrient-leached land will never return to what it once was. As a result, critical wildlife habitat —land crucial for breeding and migration —ends up fragmented and destroyed.
Coal, oil, and gas development pose myriad threats to our waterways and groundwater. Coal mining operations wash acid runoff into streams, rivers, and lakes and dump vast quantities of unwanted rock and soil into streams. Oil spills and leaks during extraction or transport can pollute drinking water sources and jeopardize entire freshwater or ocean ecosystems. Fracking and its toxic fluids have also been found to contaminate drinking water, a fact that the Environmental Protection Agency was slow to recognize.
Meanwhile, all drilling, fracking, and mining operations generate enormous volumes of wastewater , which can be laden with heavy metals, radioactive materials, and other pollutants.
Surface mining accounts for 62 percent of coal extraction. Underground mining, which creates tunnels in mountains to access coal, accounts for the other 38 percent. Both methods create environmental and human health issues in surrounding areas.
Coal combustion produces a variety of air pollutants that harm human and environmental health, such as sulfur dioxide, nitrogen oxides, mercury, and particulate matter. Coal ash is another harmful coal waste product, which is difficult to recycle and can seep into waterways, polluting them.
The Environmental Protection Agency estimates that million tons of coal ash are generated each year in the United States. Natural gas is burned to generate an increasing share of U. It is most commonly used to produce heat or electricity for buildings or industrial processes. Accessing natural gas requires drilling a well.
In the United States , natural gas is found in shale and other sedimentary rock formations and is extracted through a process called hydraulic fracturing, or fracking. Fracking requires forcing water, chemicals, and sand down a well at high pressure, which cracks the rock and releases the natural gas. This process can be extremely resource-intensive, requiring between 1. Fracking can also pollute local waterways, create contaminated wastewater, and cause earthquakes. While generating electricity from natural gas emits less carbon dioxide and other air pollutants than generating electricity from coal, leaks from natural gas plants, wells, and pipelines also emit methane—the main component of natural gas—into the atmosphere.
Methane is a greenhouse gas that is 25 times more effective than carbon dioxide at trapping heat in the atmosphere, although it remains in the atmosphere for less time. Through leakage and direct emissions from combustion, natural gas was responsible for 36 percent of greenhouse gas emissions in the United States in Natural gas consumption has been steadily increasing in the United States and is expected to continue to grow into the future as natural gas replaces coal.
Under the assumption that natural gas prices will remain low, natural gas is projected to meet an increasing share of U. In particular, its use is likely to increase in the industrial sector, where it is used as a feedstock in chemical processes and for industrial heat and power.
Coal: Black or brown chunks of sedimentary rock that range from crumbly to relatively hard, coal began to form during the Carboniferous period about to million years ago, when algae and debris from vegetation in swamp forests settled deeper and deeper under layers of mud. Mined via surface or underground methods, coal supplies a third of all energy worldwide, with the top coal consumers and producers in being China, India, and the United States. Coal is classified into four categories—anthracite, bituminous, sub-bituminous, and lignite—depending on its carbon content.
An iceberg melts in the waters off Antarctica. Climate change has accelerated the rate of ice loss across the continent. Carbon dioxide emissions from burning coal account for 44 percent of the world total , and it's the biggest single source of the global temperature increase above pre-industrial levels.
The health and environmental consequences of coal use, along with competition from cheap natural gas, have contributed to its decline in the U. But in other places, such as India, demand is expected to rise through Oil: Crude oil, a liquid composed mainly of carbon and hydrogen , is often black, but exists in a variety of colors and viscosities depending on its chemical composition.
Much of it formed during the Mesozoic period, between and 66 million years ago, as plankton, algae, and other matter sank to the bottom of ancient seas and was eventually buried. Extracted from onshore and offshore wells, crude oil is refined into a variety of petroleum products , including gasoline, diesel, and heating oil. The top oil-producing countries are the U.
Petroleum use accounts for nearly half the carbon emissions in the U. In addition to the air pollution released when oil is burned, drilling and transport have led to several major accidents, such as the Exxon Valdez spill in , the Deepwater Horizon disaster in , the devastating Lac Megantic oil train derailment in , and thousands of pipeline incidents. Nonetheless, oil demand continues to rise , driven not only by our thirst for mobility, but for the many products— including plastics —made using petrochemicals, which are generally derived from oil and gas.
Natural gas: An odorless gas composed primarily of methane, natural gas often lies in deposits that, like those for coal and oil, formed millions of years ago from decaying plant matter and organisms. Both natural gas and oil production have surged in the U.
By combining fracking—or hydraulic fracturing—with horizontal drilling and other innovations, the fossil-fuel industry has managed to extract resources that were previously too costly to reach. As a result, natural gas has surpassed coal to become the top fuel for U. Natural gas is cleaner than coal and oil in terms of emissions, but nonetheless accounts for a fifth of the world's total, not counting the so-called fugitive emissions that escape from the industry, which can be significant.
Undersea methane hydrates, for example, where gas is trapped in frozen water, are being eyed as a potential gas resource. Governments around the world are now engaged in efforts to ramp down greenhouse gas emissions from fossil fuels to prevent the worst effects of climate change.
0コメント