Course: BIS 105 Environmental Biology

Unit 14 Learning Module

Nonrenewable Energy
Copyright
Adapted from U of I Open Source Textbook. Sustainability: A Comprehensive Foundation. Connexions. 18 Sep 2012 .

Energy to illuminate, heat and cool our homes, businesses and institutions, manufacture products, and drive our transportation systems comes from a variety of sources that are originate from our planet and solar system. This provides a social and economic benefit to society. The earth’s core provides geothermal energy. The gravitational pull of moon and sun create tides. The sun makes power in multiple ways. By itself, the sun generates direct solar power. The sun’s radiation in combination with the hydrologic cycle can make wind power and hydroelectric power. Through photosynthesis, plants grow making wood and biomass that decay after they die into organic matter. Over the course of thousands of years, this decay results in fossil fuels that have concentrated or stored energy. Each of these types of energy can be defined as renewable or nonrenewable fuels and they each have some environmental and health cost.

Fossil fuel reserves are not distributed equally around the planet, nor are consumption and demand. We will see in this unit that fuel distribution is critical to the sustainability of fossil fuel resources for a given geographic area. Access to renewable resources and their viability is greatly dependent on geography and climate. Making energy requires an input of energy so it is important to look at the net energy generated – the difference of the energy produced less the energy invested.

Environmental and Health Challenges of Energy Use

The environmental impacts of energy use on humans and the planet can happen anywhere during the life cycle of the energy source. The impacts begin with the extraction of the resource. They continue with the processing, purification or manufacture of the source, its transportation to place of energy generation, effects from the generation of energy including use of water, air, and land, and end with the disposal of waste generated during the process. Extraction of fossil fuels, especially as the more conventional sources are depleted, takes a high toll on the natural environment. As we mine deeper into mountains, further out at sea, or further into pristine habitats, we risk damaging fragile environments, and the results of accidents or natural disasters during extraction processes can be devastating. Fossils fuels are often located far from where they are utilized so they need to be transported by pipeline, tankers, rail or trucks. These all present the potential for accidents, leakage and spills. When transported by rail or truck energy must be expended and pollutants are generated. Processing of petroleum, gas and coal generates various types of emissions and wastes, as well as utilizes water resources. Production of energy at power plants results in air, water, and, often, waste emissions. Power plants are highly regulated by federal and state law under the Clean Air and Clean Water Acts, while nuclear power plants are regulated by the Nuclear Regulatory Commission. As long as the facilities are complying, much of the environmental impact is mitigated by treating the emissions and using proper waste disposal methods. However, from a sustainability perspective these still present environmental threats over the long run and have a complex variety of issues around them. The figure below summarizes these challenges. Later in the unit, they are described more fully for each source of energy and examples are given.

Geopolitical Challenges of Fossil Fuels

The use of fossil fuels has allowed much of the global population to reach a higher standard of living. However, this dependence on fossil fuels results in many significant impacts on society. Our modern technologies and services, such as transportation, landscaping, and plastics production depend in many ways on fossil fuels. Meaning, if supplies become limited or extremely costly, our economies are vulnerable. If countries do not have fossil fuel reserves of their own, they incur even more risk. The United States has become more and more dependent on foreign oil since 1970 when our own oil production peaked, although domestic production has increased since 2005. We imported 40% of the crude oil and refined petroleum products that we consumed during 2012. Just over half of these imports came from the Western Hemisphere.

U.S. Petroleum, Consumption, Production, Imports

The holder of oil reserves in the oil market is the Organization of Petroleum Exporting Countries, (OPEC). There are currently 12 member countries in OPEC: Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates, and Venezuela. OPEC attempts to influence the amount of oil available to the world by assigning a production quota to each member except Iraq, for which no quota is presently set. Overall compliance with these quotas is mixed since the individual countries make the actual production decisions. All of these countries have a national oil company but also allow international oil companies to operate within their borders. They can restrict the amounts of production by those oil companies. Therefore, the OPEC countries have a large influence on how much of world demand is met by OPEC and non-OPEC supply. A recent example of this is the price increases that occurred during the year 2011 after multiple popular uprisings in Arab countries, including Libya.

This pressure has lead the United States to developing policies that would reduce reliance on foreign oil such as developing additional domestic sources and obtaining it from non-Middle Eastern countries such as Canada, Mexico, Venezuela, and Nigeria. However, since fossil fuel reserves create jobs and provide dividends to investors, a lot is at stake in a nation that has these reserves. Depending on whether that oil wealth is shared with the country’s inhabitants or retained by the oil companies and dictatorships, as in Nigeria prior to the 1990s, a nation with fossil fuel reserves may benefit or come out even worse.

Nonrenewable Energy and the Environment

Fossil fuels are also known as non-renewable energy because it takes thousands of years for the earth to regenerate them. The three main fuel sources come in all phases – solid, liquid, and gas – and will be discussed in that order. One overriding concern is the carbon dioxide emissions that contribute to climate change. The figure below displays the relationship between fuel type and carbon emissions.

Solid Fossil Fuel: Coal

Coal comes from organic matter that was compressed under high pressure to become a dense, solid carbon structure over thousands to millions of years. Due to its relatively low cost and abundance, coal is used to generate about half of the electricity consumed in the United States. Coal is the largest domestically produced source of energy. The figure below shows how coal production has doubled in the United States over the last sixty year. Current world reserves are estimated at 826,000 million tonnes, with nearly 30 percent of that in the United States. It is a major fuel resource that the United States controls domestically.

Coal is plentiful and inexpensive, when looking only at the market cost relative to the cost of other sources of electricity, but its extraction, transportation, and use produces a multitude of environmental impacts that the market cost does not truly represent. Coal emits sulfur dioxide, nitrogen oxide, and mercury, which have been linked to acid rain, smog, and health issues. Burning of coal emits higher amounts of carbon dioxide per unit of energy than the use of oil or natural gas. Coal accounted for 34 percent of the total United States emissions of carbon dioxide released into the Earth’s atmosphere in 2011. Ash generated from combustion contributes to water contamination. Some coal mining has a negative impact on ecosystems and water quality, and alters landscapes and scenic views. There are also significant health effects and risks to coal miners and those living in the vicinity of coal mines.

Traditional underground mining is risky to mine workers due to the risk of entrapment or death. Over the last 15 years, the U.S. Mine Safety and Health Administration has published the number of mine worker fatalities and it has declined over time, yet it still remains the second most dangerous occupation in the U.S.

Twenty-nine miners died on April 6, 2010 in an explosion at the Upper Big Branch coal mine in West Virginia, contributing to the uptick in deaths between 2009 and 2010. In other countries, with less safety regulations, accidents occur more frequently. Between 2000-2010 China averaged nearly 4,800 fatalities a year. If we compare the number of deaths per 1 million tons of coal, China’s miners are dying at a rate about 20 times America’s fatality rate.

There is also risk of getting black lung disease (pneumoconiosis). This is a disease of the lungs caused by the inhalation of coal dust over a long period of time. It causes coughing and shortness of breath. If exposure is stopped the outcome is good. However, the complicated form may cause shortness of breath that gets increasingly worse.

Mountain Top Mining (MTM), while less hazardous to workers, has particularly detrimental effects on land resources. MTM is a surface mining practice involving the removal of mountaintops to expose coal seams, and disposing of the associated mining waste in adjacent valleys – "valley fills." The process of MTM is described in more detail by the U.S. Environmental Protection Agency (U.S. EPA).

Photograph shows mountaintop coal removal mining in Martin County, Kentucky.

The following are some examples of the impact of MTM:

- an increase of minerals in the water that negatively impact fish and macroinvertebrates, leading to less diverse and more pollutant-tolerant species

- streams are sometimes covered up by silt from mining

- the re-growth of trees and woody plants on regraded land may be slowed due to compacted soils

- affects the diversity of bird and amphibian species in the area since the ecosystem changes from wooded areas to other

- there may be social, economic and heritage issues created by the loss of wooded land that may have been important to traditions and economies of the area

A study by Epstein, et al. (2011) assigned a monetary value (full cost accounting) for the life cycle of coal in the United States, accounting for many environmental and health impacts of coal. The authors found the cost to be about $0.178/kWh of electricity generated from coal ($345.4 billion in 2008), doubling or tripling the price of coal-generated electricity. This study accounted for all of the impacts discussed above and more.

Liquid Fossil Fuel: Petroleum

Thirty seven percent of the world’s energy consumption and 43 percent of the United States energy consumption comes from oil. As discussed above, most of the oil production is in the Gulf region. Scientists and policy-makers often discuss the question of when the world will reach peak oil production, and there are a lot of variables in that equation, but it is generally thought that peak oil will be reached by the middle of the 21^st Century. Currently world reserves are 1.3 trillion barrels, or 45 years left at current level of production, but we may reduce production as supplies run low.

Environmental Impacts of Oil Extraction and Refining

Oil is usually found one to two miles (1.6 – 3.2 km) below the surface. Oil refineries separate the mix of crude oil into the different types for gas, diesel fuel, tar, and asphalt. To find and extract oil workers must drill deep below ocean floor. As the United States tries to extract more oil from its own resources, we are drilling even deeper into the earth and increasing the environmental risks.

The largest United States oil spill to date began in April 2010 when an explosion occurred on Deepwater Horizon Oil Rig killing 11 employees and spilling nearly 200 million gallons of oil before the resulting leak could be stopped. Wildlife, ecosystems, and people’s livelihood were adversely affected. A lot of money and huge amounts of energy and waste were expended on immediate clean-up efforts. The long-term impacts are still not known. The National Commission on the Deepwater Horizon Oil Spill and Offshore Drilling was set up to study what went wrong.

On April 20, 2010 an explosion tore through the Deepwater Horizon, an oil rig operating in the Gulf of Mexico. The disaster happened as workers were finalizing the drilling of the exploratory Macondo well, forty miles off the coast of Louisiana. It was, by any standard, a catastrophe. See the project at http://www.oilspillcommission.gov/media

Once oil is found and extracted it must be refined. Oil refining is one of top sources of air pollution in the United States for volatile organic hydrocarbons and toxic emissions, and the single largest source of carcinogenic benzene.

When petroleum is burned as gasoline or diesel, or to make electricity or to power boilers for heat, it produces a number of emissions that have a detrimental effect on the environment and human health:

- Carbon dioxide (CO_2) is a greenhouse gas and a source of climate change.

- Sulfur dioxide (SO_2) causes acid rain, which damages plants and animals that live in water, and it increases or causes respiratory illnesses and heart diseases, particularly in vulnerable populations like children and the elderly.

- Nitrous oxides (NO_x) and Volatile Organic Carbons (VOCs) contribute to ozone at ground level, which is an irritatant and causes damage to the lungs.

- Particulate Matter (PM) produces hazy conditions in cities and scenic areas, and combines with ozone to contribute to asthma and chronic bronchitis, especially in children and the elderly. Very small, or “fine PM,” is also thought to penetrate the respiratory system more deeply and cause emphysema and lung cancer.

- Lead can have severe health impacts, especially for children.

- Air toxins are known or probable carcinogens.

There are other domestic sources of liquid fossil fuel that are being considered as conventional resources and are being depleted. These include oil sands/tar sands – deposits of moist sand and clay with 1-2 percent bitumen (thick and heavy petroleum rich in carbon and poor in hydrogen). These are removed by strip mining. Another source is oil shale in United States west which is sedimentary rock filled with organic matter that can be processed to produce liquid petroleum. Also, mined by strip mines or subsurface mines, oil shale can be burned directly like coal or baked in the presence of hydrogen to extract liquid petroleum. However, the net energy values are low and they are expensive to extract and process. Both of these resources have severe environmental impacts due to strip mining, carbon dioxide, methane and other air pollutants similar to other fossil fuels.

Gaseous Fossil Fuel: Natural Gas

Natural gas meets 20 percent of world energy needs and 25 percent of United States needs. Natural gas is mainly composed of methane, the shortest hydrocarbon (CH_4), and is a very potent greenhouse gas. There are two types of natural gas. Biogenic gas is found at shallow depths and arises from anaerobic decay of organic matter by bacteria, like landfill gas. Thermogenic gas comes from the compression of organic matter and deep heat underground. They are found with petroleum in reservoir rocks and with coal deposits, and these fossil fuels are extracted together.

Methane is released into the atmosphere from coal mines, oil and gas wells, and natural gas storage tanks, pipelines, and processing plants. These leaks are the source of about 25 percent of total U.S. methane emissions, which translates to three percent of total U.S. greenhouse gas emissions. When natural gas is produced but cannot be captured and transported economically, it is "flared," or burned at well sites. This is considered to be safer and better than releasing methane into the atmosphere because CO_2 is a less potent greenhouse gas than methane.

In the last few years a new reserve of natural gas has been identified - shale resources. The United States possesses 2,552 trillion cubic feet (Tcf) (72.27 trillion cubic meters) of potential natural gas resources, with shale resources accounting for 827 Tcf (23.42 tcm). As gas prices increased it has become more economical to extract the gas from shale. The figure below shows the past and forecasted U.S. natural gas production and the various sources. The current reserves are enough to last about 110 years at the 2009 rate of U.S. consumption (about 22.8 Tcf per year -645.7 bcm per year).

Natural gas is a preferred energy source when considering its environmental impacts. Specifically, when burned, much less carbon dioxide (CO_2), nitrogen oxides, and sulfur dioxide are omitted than from the combustion of coal or oil. It also does not produce ash or toxic emissions.

Environmental Impacts of Exploration, Drilling, and Production

Land resources are affected when geologists explore for natural gas deposits on land, as vehicles disturb vegetation and soils. Road clearing, pipeline and drill pad construction also affect natural habitats by clearing and digging. Natural gas production can also result in the production of large volumes of contaminated water. This water has to be properly handled, stored, and treated so that it does not pollute land and water supplies.

Extraction of shale gas is more problematic than traditional sources due to a process nicknamed “fracking,” or fracturing of wells, since it requires large amounts of water (see figure below). The considerable use of water may affect the availability of water for other uses in some regions and this can affect aquatic habitats. If mismanaged, hydraulic fracturing fluid can be released by spills, leaks, or various other exposure pathways. The fluid contains potentially hazardous chemicals such as hydrochloric acid, glutaraldehyde, petroleum distillate, and ethylene glycol. The risks of fracking have been highlighted in popular culture in the documentary, Gasland (2010).

Fracturing also produces large amounts of wastewater, which may contain dissolved chemicals from the hydraulic fluid and other contaminants that require treatment before disposal or reuse. Because of the quantities of water used and the complexities inherent in treating some of the wastewater components, treatment and disposal is an important and challenging issue.

The raw gas from a well may contain many other compounds besides the methane that is being sought, including hydrogen sulfide, a very toxic gas. Natural gas with high concentrations of hydrogen sulfide is usually flared which produces CO_2, carbon monoxide, sulfur dioxide, nitrogen oxides, and many other compounds. Natural gas wells and pipelines often have engines to run equipment and compressors, which produce additional air pollutants and noise.