Energy Sciences

Nonrenewable Energy

Oil

The first type of energy source is oil, also known as crude oil. Oil may happen to be one of the most contentious energy sources out there as it has sparked wars, split nations, and has caused the demise of forests, animal habitats, and organisms. Oil is formed from the remains of organisms that lived millions of years ago in marine environments. Once the organisms died, they became buried by sand, silt, mud, etc. and through the impact of heat and pressure over time, deposits of oil developed as portrayed in Figure 3.

Figure 3: The process of crude oil development.¹⁰

Globally, oil makes up about 35% of the world's energy consumption.¹¹ There are many factors that affect the availability of oil which include the demand, technology, rate of removal, cost of production, and market price. We obtain oil from many different places such as shale rock, tar sands, and oil wells. There are several main issues with oil, one being the fact that it contains combustible hydrocarbons, sulfur, oxygen, and nitrogen impurities. Once the oil is extracted, processed, and used, it releases carbon dioxide into the atmosphere. Carbon dioxide is readily available in the atmosphere as it is a natural product of respiration; however, the issue comes from the anthropogenic increases in carbon dioxide levels. “In 2017, CO₂ accounted for about 81.6 percent of all U.S. greenhouse gas emissions from human activities.” As mentioned in the background section, there is a correlation between the increase in atmospheric CO₂ and human induced burning of fossil fuels. The percentage of CO₂ has increased with an increase in more modern technology. “Human activities are altering the carbon cycle–both by adding more CO₂ to the atmosphere, by influencing the ability of natural sinks, like forests, to remove CO₂ from the atmosphere, and by influencing the ability of soils to store carbon.”¹²

When extracting oil from different locations, there can be an impact on the environment at the surface and at the atmospheric level. One example is the impacts on marine environments when there are marine oil spills. “The toxic effect of oil on marine life depends on the duration of exposure and oil concentration in the environment.”¹³ Organisms further away from the shore and organisms less likely to be coated with oil are less likely to suffer long term effects from oil spills. There are also human health impacts that can range from direct effects resulting from the presence of carcinogens in crude oil to the indirect effects from air pollution resulting from the presence of oil or the burning of oil. On the same note, different types of oil have their own risks that can vary in their impact on humans and the environment. Conventional oil, which is characteristic of the typical crude oil, has a low-land disruption and a moderate environmental impact compared to unconventional oil. Unconventional oil, characteristic of oils coming from shale rock and tar sands, potentially have a large supply available but to obtain that supply, there is a large environmental impact and severe land disruption.¹⁴

Natural Gas

Next, there is natural gas which makes up about 23.9% of the world’s total energy consumption.¹⁵ Natural gas contains a mixture of different gases such as methane with varying amounts of propane, butane, and hydrogen sulfide. As can be seen in Figure 3 above, natural gas forms in a similar fashion as crude oil. Over time with the assistance of heat and pressure, organic remains become converted into pockets of natural gas deposits. We utilize natural gas in cooking, heating, and as fuel to produce electricity. An upside of using natural gas is that it burns cleaner than oil and coal; however, there is some controversy regarding the extraction of natural gas through the form of hydraulic fracturing. Natural gas is extracted from shale rock which requires drilling of wells into the rock and the use of water, sand, and chemicals to frack the gas. “More than 750 distinct chemicals, ranging from benign to toxic, have been used in hydraulic fracturing solutions.”¹⁶ To extract the natural gas from the shale rock, companies inject a mixture of liquid, sand, and chemicals which increases the pressure near the fissures which increases the size of the fissures, releasing the natural gas. Some issues with fracking are water contamination due to leaks in cement barriers, tanker truck spills, migration through fractures, site surface contamination, and disposal of hydraulic fracturing fluids.¹⁷ Consequently, this pollution can seep into natural waterways where communities obtain their source of water for human consumption and irrigation practices. At the same time, another issue arises from aquifers becoming depleted due to the high volume of water needed and the degradation of aquatic habitats near areas of fracking sites. Proponents of fracking claim that there is no actual contamination from the hydraulic fracturing process, but the contamination occurs due to leaks in faulty cement seals and well pipes. This is a result of inadequate inspections and regulation of the natural gas industry and not of the fracking process itself.¹⁸ An additional side effect of using natural gas is the human health impacts from different stages of its usage. The chemicals alone can “… affect the skin, eyes, and other sensory organs, and the respiratory and gastrointestinal systems.”¹⁹ When toxic volatile compounds, hydrocarbons, and fugitive gas (emissions of gasses or vapors from pressurized equipment due to leaks) mix with nitrogen oxides in the atmosphere, low-level ozone is formed. As a result, molecules in the low-level ozone can burn the deep alveolar tissue in the lungs causing premature aging which can lead to asthma, chronic obtrusive pulmonary disease (COPD), and are damaging to those that spend time outdoors.²⁰

Coal

A third type of nonrenewable energy source is coal. Coal makes up approximately 28.25% of the world's energy consumption.²¹ Coal is in solid form which is made up of the remains of plants that were buried about 300 to 400 million years ago as can be seen in Figure 3 above. Over time, pressure and heat convert organic matter to coal that are dependent on time and carbon concentration. Not all coal is the same. Some forms of coal are best used in some industries and not so much in others. There are four different types of coal that vary in their carbon content which makes a difference when burning coal for energy production. The higher the carbon concentration, the higher the heat value is. The first type of coal is anthracite which is the most sought-after coal type for settings that require a high heat value. Generally, anthracite has a concentration of carbon anywhere between 86%-97% which implies that its moisture ratio is low compared to the carbon ratio. The second type of coal is bituminous which is used a great deal in electricity and steel production. Bituminous coal contains about 45%-86% carbon content. The third type of coal is subbituminous which is used in electricity generation and contains a lower carbon content than the previous two at a mere 35%-45%. Lastly, the fourth type of coal is lignite which is used in electricity production as well. Lignite’s carbon content varies from 25%-35% carbon and is less durable than the other forms of coal.^{22, 23} Coal is burned in power plants to aid in the production of steel, cement, and energy use. There is mostly carbon in coal but there can be trace amounts of sulfur. When coal is burned it produces soot, mercury, carbon dioxide, and radioactive material. The major benefit of coal is the fact that it is very abundant and cheap. Due to this reason, it drives a lot of political decisions made in the United States. There are environmental impacts that affect land, water, and human health. Coal is extracted by mining. As a result, soil and rock become removed, explosives are used to remove mountaintops, and acid mine drainage results from underground mines. U.S. laws dictate how much reclamation must occur with the different types of mining that occur. Another important issue is the emission of carbon dioxide or sulfur dioxide into the atmosphere which contributes to the overall percentage of greenhouse gases which traps heat near the surface of Earth resulting in warming events. This trapped heat helps increase the average temperatures near the surface of Earth. When the temperatures increase, we see an increase in evaporation rates, extreme weather, and extinction events.²⁴ Emissions from burning coal can cause acid rain, respiratory illnesses, smog, lung disease, neurological and developmental damage in both humans and animals, and pollution that leaches out of ash storage that impacts waterways.²⁵

Nuclear

A fourth type of nonrenewable energy is nuclear. Worldwide, there are approximately 450 nuclear power reactors that supply 1.72% of the world’s energy consumption.²⁶ Nuclear energy comes from the process known as nuclear fission where a neutron and a uranium atom collide (Figure 4). When they collide, heat, energy, and neutrons are released. In return, the neutrons continue the chain reaction by colliding with other uranium atoms creating more heat, energy, and neutrons.²⁷

Figure 4: This image depicts the process of an atom of Uranium-235 splitting due to the process of nuclear fission.²⁸

Nuclear energy is created within a vessel in order to contain the reaction and the emission of nuclear radiation as well as the rate at which the reactions occur.²⁹ The energy created from nuclear fission is used to make steam which powers generators to produce electricity. Some benefits of utilizing nuclear energy are the relatively low cost of production, reliability, and the fact that it can be nonpolluting.³⁰ At the same time, nuclear energy produces no carbon emissions during its operation. The issue arises in the creation of nuclear power plants. Concrete is a material used in the development of nuclear power plants. The production of concrete utilizes aggregates and rocks as well as limestone. Limestone becomes disassociated by the burning off of carbon dioxide and lime remains, acting as a mortar for the concrete. In this sense, nuclear power plants are not emission free as every step of the production must be considered. One of the other major issues associated with nuclear energy is the environmental risk due to the creation of radioactive wastes. The radioactive wastes produced are easy to transfer to the environment as they can be transferred to the environment by “… workers’ shoe covers, clothing, mops, equipment, and reactor water residues.”³¹ Lastly, just like any man-made energy source, nuclear energy comes with its risks to human health. Some consequences that arise from radiation exposure range from DNA damage, acute radiation sickness, and long-term cancer risks. The associated health risks can be temporary or permanent and can vary based on the type of radiation exposure and the amount of exposure.