Just as the 19th century belonged to coal and the 20th century to oil,
the 21st century will belong to the sun, the wind, and energy from within the earth.
(Lester R. Brown: Plan B 3.0: Mobilizing to Save Civilization, 2008)
What is Energy?
The United States Energy Administration (“Oil: Crude and Petroleum Products Explained,” 2017) defines energy as the ability to do work. Energy may be stored (potential) or working (kinetic). As an example, the food a person eats contains energy that is stored (potential energy) until the person engages in some activity that requires energy and it is put to work (kinetic energy).
An important distinction exists among the sources from which we obtain energy. Today, we still rely on energy sources that are nonrenewable. These energy sources – like natural gas, crude oil, and coal – have only a finite amount available and are not (or not easily) replenishable. When they are used up, they are gone. Moreover, these energy sources are often referred to as being “dirty energy.” They have been shown to damage people’s health, to harm the environment, and to very significantly contribute to climate change.
This is the reason that many people urge that the United States (and all other countries) shift to use and dependence on renewable sources of energy. There is an infinite amount of these energy sources available (or they are easily replenishable), that is, they will never run out. These energy sources are sometimes referred to as being “clean energy,” because, when obtained and produced appropriately, they do not produce carbon emissions and other harmful air pollutants. Because of this, they do not damage people’s health, they do not harm the environment, and they do not contribute to climate change.
Energy Consumption. In order to compare energy usage among countries or over time or among different types of users, it is helpful to have a single way of measuring energy. This does not occur naturally because energy sources are measured in different physical units: liquid fuels are measured in terms of barrels or gallons, natural gas in cubic feet, coal in short tons, and electricity in kilowatts and kilowatt hours. In the United States, we typically use British thermal units (Btu), a measure of heat energy, for comparing different types of energy consumption with each other. In 2016, total U.S. primary energy consumption was about 97.4 quadrillion (one thousand trillion) Btu.
The three countries in the world that consume the most energy are 1) China (22 percent of energy used; has 18.7 percent of world population), 2) United States (18 percent of energy used; has 4.3 percent of world population), and 3) Russia (6 percent of energy used; has 1.9 percent of world population).
Energy Production. In 2016, energy produced in the United States was equal to about to about 86% of U.S. energy consumption. The difference between production and consumption was mainly in net imports of petroleum. The three major fossil fuels—petroleum, natural gas, and coal—have accounted for most of the nation's energy production for the last 100 years and continued to do so in 2016.
1. Natural gas—33% (and increasing)
2. Petroleum (crude oil and natural gas plant liquids)—28% (and fluctuating)
3. Coal—17% (but decreasing)
4. Combined renewable energy—12% (and increasing; at record highs)
5. Nuclear electric power—10%
Net Energy Yield. In determining the cost of producing any type of energy, it is crucial to consider the concept net energy yield. Net energy yield is defined as the amount of energy available from a resource minus the amount of energy needed to make it available. Miller and Spoolman (2016) express the rationale for this concept.
It takes energy to produce energy. For example, before oil becomes useful to us, it must be found, pumped up from beneath the ground or the ocean floor, transferred to a refinery, converted to gasoline and other fuels and chemicals,and delivered to consumers. Each of these steps uses high-quality energy, obtained mostly by burning fossil fuels, especially gasoline and diesel fuel…Suppose that it takes about nine units of high-quality energy to produce ten units of high-quality energy from an energy resource. Then, the net energy yield is one unit of energy.
In considering the advantages and disadvantages of any energy resource, net energy yield must be considered.
Nonrenewable Sources of Energy
The United States currently relies heavily on nonrenewable sources of energy such as coal, oil, and natural gas. These fossil fuels are non-renewable because they draw on finite resources that will eventually dwindle and/or become too expensive or too environmentally damaging to retrieve. The four main types of nonrenewable energy sources we use are:
1. Crude oil and petroleum products. Crude oil (also known as petroleum) is a black, gooey liquid containing a mixture of combustible hydrocarbons along with small amounts of sulfur, oxygen, and nitrogen impurities. It was formed by the decayed remains of ancient plants and animals that were crushed beneath layers of rock for millions of years. Crude oil is a fossil fuel, and it exists in liquid form in underground pools or reservoirs, in tiny spaces within sedimentary rocks, and near the surface in tar (or oil) sands. Petroleum products are fuels made from crude oil and other hydrocarbons contained in natural gas. Petroleum products can also be made from coal, natural gas, and biomass.
Typically, crude oil is discovered and brought to the surface through drilling, it is transported to a refinery by pipeline, truck, rail, or ship, where it is heated to separate it into various types of petroleum products. These petroleum products include gasoline, diesel fuel, heating oil, jet fuel, petrochemical feedstocks, waxes, lubricating oils, and asphalt. All of these steps are expensive and require input of high-quality energy. This decreases the net energy yield of oil [Miller and Spoolman, 2016; United States Energy Administration (“Hydrocarbon Gas Liquids Explained”), 2017].
Advantages: current ample supply, low land disruption leaks, net energy yield is medium (but decreasing)
Disadvantages: only finite amount, harms from water spills, releases carbon dioxide and other air pollutants, contributes to climate change
2. Natural Gas. Natural gas is a mixture of gases of which 50 to 90 percent is methane with smaller percentages of hydrocarbon gas liquids, propane, butane, and highly toxic hydrogen sulfide. It is found deep beneath the earth's surface in deposits lying above deposits of crude oil. Natural gas began developing millions of years ago as the remains of plants and animals decayed and built up in thick layers, sometimes mixed with sand and silt. Over time, these layers were buried under rock. Pressure and heat changed some of this organic material into coal, some into oil (petroleum), and some into natural gas. In some places, the natural gas moved into large cracks and spaces between layers of overlying rock. In other places, natural gas occurs in the tiny pores spaces within some formations of shale, sandstone, and other types of sedimentary rock.
(Source: Adapted from The National Energy Education Project)
Typically, when a natural gas deposit is located and tapped, its propane and butane gases are liquefied by high pressure techniques and removed. These gases are stored in pressurized tanks and used mostly in rural areas without access to natural gas lines and for backyard grills. The rest of the gas (mostly methane) is purified and pumped into pressurized pipelines for distribution across land areas. This gas is widely used in cooking, heating, for industrial purposes, and as fuel for cars and trucks. When it is converted into liquefied form, it can be transported in refrigerator tanker ships [Miller and Spoolman, 2016; United States Energy Administration (“Gas Explained”), 2017].
Advantages: current ample supply, low land disruption, net energy yield is medium
Disadvantages: only finite amount, harms from water spills and leaks, releases carbon dioxide, contributes to climate change
3. Coal. Coal is a combustible black or brownish-black solid sedimentary rock with a high amount of carbon and hydrocarbons and a small amount of sulfur. Coal takes millions of years to form. It contains the energy stored by plants that lived 300 to 400 millions of years ago in swampy forests and were covered by layers of dirt and rock. The resulting pressure and heat turned the plants into the substance we call coal.
Coal-burning power plants provide about 40 percent of the world’s electricity and just under that percentage in the United States. Coal is also burned in industrial plants to make steel, cement, and other products.
Coal is classified into four main types (ranks): anthracite, bituminous, subbituminous, and lignite [United States Energy Administration (“Coal Explained”), 2017]. The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce. The rank of a coal deposit is determined by the amount of pressure and heat that acted on the plants over time.
Anthracite (1% of coal production) contains 86%–97% carbon and generally has the highest heating value of all ranks of coal. Bituminous coal contains 45%–86% carbon. Bituminous coal accounts for 45% of total U.S. coal production; it has the second highest heating value. Subbituminous coal typically contains 35%–45% carbon, and it has a lower heating value than bituminous coal. It accounts for just under half of total U.S. coal production. Lignite contains 25%–35% carbon and has the lowest energy content of all coal ranks.
Advantages: current ample supply (in many countries), cheap to produce except for human health and environmental harms, medium to high net energy yield damage human health
Disadvantages: only finite supply, severe land disturbance and water pollution, fine particle and toxic mercury emissions damage human health, releases carbon dioxide and other air pollutants, contributes to climate change
4. Nuclear. Nuclear energy is energy in the core of an atom. Atoms are the tiny particles in the molecules that make up gases, liquids, and solids. Atoms themselves are made up of three particles called protons, neutrons, and electrons. An atom has a nucleus (or core) containing protons and neutrons, which is surrounded by electrons. Protons carry a positive electrical charge and electrons carry a negative electrical charge. Neutrons do not have an electrical charge. Enormous energy is present in the bonds that hold the nucleus together. This nuclear energy can be released when those bonds are broken. The bonds can be broken through nuclear fission, and this energy can be used to produce electricity.
In nuclear fission, atoms are split apart, which releases energy. All nuclear power plants use nuclear fission, and most nuclear power plants use uranium atoms. During nuclear fission, a neutron collides with a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation. More neutrons are also released when a uranium atom splits. These neutrons continue to collide with other uranium atoms, and the process repeats itself over and over again. This process is called a nuclear chain reaction. This reaction is controlled in nuclear power plant reactors to produce a desired amount of heat.
The sun is basically a giant ball of hydrogen gas undergoing fusion and giving off vast amounts of energy in the process
Uranium is the fuel most widely used by nuclear plants for nuclear fission. Uranium is considered a nonrenewable energy source, even though it is a common metal found in rocks worldwide. Nuclear power plants use a certain kind of uranium, referred to as U-235, for fuel because its atoms are easily split apart. Although uranium is about 100 times more common than silver, U-235 is relatively rare. Most U.S. uranium ore is mined in the western United States. Once uranium is mined, the U-235 must be extracted and processed before it can be used as a fuel.
Nuclear energy can also be released in nuclear fusion, where atoms are combined or fused together to form a larger atom. Fusion is the source of energy in the sun and stars. Nuclear fusion is the subject of ongoing research as a source of energy for heat and electricity generation, but whether or not it will be a commercially viable technology is not yet clear because of the difficulty in controlling a fusion reaction. (This entire section is verbatim from United States Energy Administration, “Nuclear Explained, 2017.)
Advantages: low environmental impact (if no accidents), low risk of accidents in modern plants, emits 1/6 carbon dioxide as coal
Disadvantages: long-lived harmful radioactive waste, high overall cost, low net energy yield
Net Energy Yield from Nonrenewable
Sources of Energy
For For For For
Electricity Heating Industrial Heat Transportation
Crude oil ----- medium medium low
Natural gas medium medium medium medium
Coal high ----- high -----
Nuclear low ----- ----- -----
Harms from Nonrenewable Sources of Energy
It is also essential to consider the amount of harm done to the environment in the process of acquiring and using any energy resource. Not surprisingly, the types of energy on which we depend and the techniques for identifying its location, gaining access to it, withdrawing it, processing it, transporting it, and using it have profound implications on human health and well-being both directly and indirectly through their effect on the environment. Among the most important effects of our dependence on nonrenewable types of energy are the following five outcomes.
1. An increase in climate change. Perhaps the most well-known impact of relying on nonrenewable “dirty” energy sources is the emission of greenhouse gases (especially carbon dioxide and methane) which, according to almost all of the world’s scientists, have contributed enormously to climate change. The burning of any carbon-containing fossil fuel releases the greenhouse gas carbon dioxide into the atmosphere. This gas damages the ozone layer which protects us from the sun's radiation and allows more of the heat provided by the sun to impact the earth. This warms the planet and creates many significant harms.
Coal is the dirtiest of the dirty sources as it emits the highest percentage of carbon dioxide. Almost ¾ of the carbon dioxide emissions from the electric power sector are attributable to coal (and 28 percent to natural gas). A 2004 study concluded that pollution from coal-powered plants shortened nearly 24,000 lives a year in the U.S. However, drilling and extracting natural gas from wells results in a higher amount of leakage of methane – a powerful greenhouse gas that traps heat on the earth’s surface.
2. An increase in water pollution. Use of nonrenewable energy sources contributes directly to water pollution in a variety of ways. For example, acid rain is created by the emission of sulfur and other chemicals into the atmosphere, often from the conversion of fossil fuels into electricity. Once there, it can follow the water cycle as the now-mildly acidic rain falls to earth. The acid rain changes the acidity of lakes and streams which can be very harmful to fish and other aquatic organisms and is damaging to trees thereby weakening forest ecosystems.
Water pollution is also increased through a process known as thermal pollution. Both fossil fuel plants and nuclear power plants require water to run and help cool the power plant. The water they use is also needed for other purposes, such as maintaining local ecosystem functions or agriculture. When the plants release that water back into the environment, its temperature is changed and as a result its quality has been degraded. This heated water contains lower levels of dissolved oxygen which can stress native wildlife by, for example, increasing the heart rate of fish or decreasing fertility (Green Tumble Editorial Staff, 2017).
In addition the presence of offshore drilling procedures increases the chances for oil spills and oil leaks. Oil spills are extremely damaging to nearby shores and ecosystems, and they are also economically damaging. Analysts estimated British Petroleum's oil spill of 2010 cost $2.5 billion in losses to the Louisiana fishing market alone. Florida was estimated to have lost $3 billion in tourism income. Biologists worried that Sargassum algae, vital to hundreds of species of animals, was almost completely destroyed due to the oil released in the Gulf of Mexico (Stefan, 2017).
3. An increase in land pollution and waste generation. Nonrenewable sources of energy typically create significant land pollution and waste generation. For example, there is very clear evidence illustrating the impact of surface mining on surrounding areas both in the short and long-term. Huge volumes of excess rock or soil typically are dumped in nearby locations thus affecting those ecosystems and denying alternative uses of the land. Environmental harm also occurs as a result of the disposal of waste that is left over from the use of nonrenewable, dirty energy sources. For example, the incineration of waste creates harmful ash that is often stored in solid waste containment areas which are prone to rupturing and causing havoc in the surrounding areas. Furthermore, the process of extracting and drilling for oil or natural gas results in massive disturbances to vegetation and soil (which harms wildlife) and is exacerbated by the many vehicles, pipelines, storage facilities, and so on used (Priebe, 2011).
4. An increase in air pollution. Nonrenewable energy sources affect the atmosphere in ways other than through greenhouse gases. They emit a variety of air pollutants that impact people’s health and the environment. For example, coal-fired power plants are the single largest source of mercury emissions in the United States. When mercury is emitted into the air, it goes on to settle on the ground or blends with water. From that point it accumulates in organisms such as fish, and passes through the food chain to humans. This has profound effects on our biodiversity, but it also creates real risks for people as studies have found that exposure to mercury can lead to neurological and neuro-behavioral effects in embryos, young children, and adults. When some types of crude oil are burned, they emit lead and various air toxins (such as benzene, formaldehyde, acetaldehyde, and 1,3-butadiene) - all of which come with significant human health hazards (Priebe, 2011). Other air pollutants emitted due to fossil fuel combustion include sulfur dioxide, nitrogen oxides, and particulate matter (Green Tumble Editorial Staff, 2017).
5. An increase in storage of dangerous materials. An obvious example of storage problems related to use of nonrenewable energy sources occurs with nuclear energy. According to Miller and Spoolman (2015):
The high-grade uranium fuel in a typical nuclear reactor lasts for 3-4 years, after which it becomes spent, or useless, and must be replaced. The spent-fuel rods are so thermally hot and highly radioactive that they cannot simply be thrown away. Researchers have found that 10 years after being removed from a reactor, a single spent-fuel rod assembly can still emit enough radiation to kill a person standing 39 inches away in less than 3 minutes....After spent-fuel rod assemblies are removed from reactors, they are stored in water-filled pools. After several years of cooling and decay of some of their radioactivity, they can be transferred to dry casks made of heat-resistant metal alloys and concrete and filled with inert helium gas. These casks are licensed for 20 years and could last for 100 years or more – only a tiny fraction of the thousands of years that the radioactive waste must be safely stored.
Electricity generation. Another way of looking at these harms is provided by focusing on just the generation of electricity in the United States (Buy Clean Energy, 2017).
Traditional electricity generation is responsible for the emission of a host of chemicals with widespread environmental impacts. The same compounds that are detrimental to human health have similar consequences for the natural environment. Electricity generation from fossil fuels is responsible for:
37% of the nation’s carbon dioxide, a greenhouse gas and major contributor to climate change. Carbon dioxide is released into the atmosphere when fossil fuels are burned. Climate change is a serious environmental threat that may contribute to coastal flooding, more frequent and extreme heat waves, more intense droughts, an increase in the number of severe storms, and the increased spread of infectious diseases.
66% of the nation’s sulfur dioxide, which when combined with rain water, creates acid rain. Acid rain damages the foliage of forests, crops, and other plants, and eventually can kill the plants. It also acidifies rivers and lakes causing them to be biologically “dead.” Acidification also alters the chemistry of soil, releasing harmful metals into rainwater runoff and groundwater. Sulfur dioxide also accelerates the decay of stone and paint, damaging many buildings and monuments.
40% of the nation’s mercury contributing to contamination of soil and waterways. Mercury can circulate in the air for up to one year and can be transported thousands of miles from its source. Mercury accumulates in the fatty tissue of fish and is constantly being recycled in the environment as it moves up the food chain. Mercury causes permanent damage to the liver and central nervous system and can cause birth defects.
25% of nitrogen oxides, which react with sunlight to create ground level ozone and smog. Nitrogen oxide deposition causes algae blooms in lakes and streams. This depletes the water of oxygen, killing fish and other living organisms. Nitrogen dioxide has also been shown to cause pulmonary disease in animals.
Particulate matter is the major cause of reduced visibility (haze) in the U.S. Coal-fired power plants are the single largest source of emissions of particulate pollution - soot particles made of ash (heavy metals, radioactive isotopes, hydrocarbons, sulfates, and nitrates) that can transport and deposit trace metals such as mercury hundreds of miles from their source. Soot stains and damages stone and other materials, damaging many of our buildings and monuments. After traveling long distances, particles settle on ground or water, causing these effects:
making lakes and streams acidic
changing the nutrient balance in coastal waters and large river basins
depleting the nutrients in soil
damaging sensitive forests and farm crops
affecting the diversity of ecosystem
Renewable Sources of Energy
Renewable sources of energy are those that come from a source that is constantly renewed, such as the sun or wind, and can be replenished in a short period of time. They never run out! Most renewable sources of energy come directly or indirectly from the sun. In addition to solar (sunlight), the sun drives the winds (wind energy) and when combined, they cause water to evaporate which is the first step in harnessing hydroelectric (water) power. Energy from ocean waves is driven by both the tides and winds. Sunlight also causes plants to grow, and the organic matter that makes up plants can eventually become biomass – another source of energy (Renewable Energy World, 2017).
1. Energy Efficiency is unlike the five other types of nonrenewable energy described in this section, but it would be inappropriate not to include it here. Energy efficiency is a measure of how much useful work we can get from each unit of energy we use. Improving energy efficiency means using less energy to provide the same amount of work (Miller and Spoolman, 2016).
A surprisingly large amount (84 percent) of the commercial energy produced in the United States is wasted. About 9 percent of energy produced is useful energy and an additional 7 percent is used in the making of petrochemicals. However, about 41 percent of energy unavoidably ends up as low-quality waste heat. This occurs as one form of energy is converted to another in a physical or chemical change. This produces low-quality heat that flows into the environment. The remaining 43 percent of all energy produced is wasted unnecessarily mostly due to the inefficiency of industrial motors, most motor vehicles, power plants, and numerous other energy-consuming devices (Miller and Spoolman, 2016). Key wasted energy occurs as:
Many people live in homes that are poorly insulated. These buildings require excessive heating in cooler months and excessive cooling in warmer months.
Many people commute to work , mostly in energy-inefficient vehicles. Only 20 percent of the gasoline used in motor vehicles provides transportation; the other 80 percent ends up as waste heat in the environment.
Huge data centers that process information flowing on the Internet and provide space for cloud-based data storage services generally run at maximum 24 hours a day even when demand is less. In addition they use large amounts of energy for cooling. This results in effective use of only 10 percent of the electrical energy used.
Advantages: prolongs fossil fuel supplies, improves energy security, very high net energy yield, low cost, reduces pollution and environmental degradation, buys time to phase in renewable energy, creates local jobs
2. Biomass consists of organic material (plant material or animal waste) that can be burned as fuel or converted into liquid or gaseous biofuels. It is a renewable source of energy. It includes wood and wood processing wastes (e.g., sawdust), municipal solid waste (i.e., garbage), alcohol fuels (e.g., ethanol), and biodiesel. Biomass contains stored energy from the sun. Plants absorb the sun's energy in photosynthesis. When biomass is burned, the chemical energy in biomass is released as heat.
(Source: Adapted from The National Energy Education Project)
(Source: Adapted from The National Energy Education Project)
Advantages: renewable, widely available in many areas, no carbon dioxide increase (if done sustainably), medium net energy yield
Disadvantages: unless replanting, contributes to deforestation, can open ecosystems to invasive species, clear cutting can cause soil erosion, water pollution, loss of habitat
3. Hydropower is energy from moving water; it is any technology that uses the kinetic energy of flowing or falling water to produce electricity. It is an indirect form of solar energy because it depends on the evaporation of water, which is in turn deposited as rain or snow at higher elevations from where it can flow to lower elevations as part of the earth’s water cycle (Miller and Spoolman, 2016). Hydropower is one of the oldest sources of energy for producing mechanical and electrical energy. Hydropower was used thousands of years ago to turn paddle wheels to help grind grain. Before steam power and then electricity were available in the United States, grain and lumber mills were powered directly with hydropower.
(Source: Adapted from National Energy Education Development Project)
The most common approach used to harness hydropower is to build a high dam across a large river to create a reservoir. Some of the water stored at the reservoir is allowed to flow through large pipes at controlled rates to spin turbines that produce electricity (Miller and Spoolman, 2016). Hydropower is the largest renewable energy source for electricity generation in the United States. It produces about 10 percent of the nation’s energy (Renewable Energy World, 2017). Miller and Spoolman’s (2016) analysis of hydropower:
Advantages: renewable, large untapped potential, low emissions of carbon dioxide and other air pollutants, low-cost electricity, high net energy yield
Disadvantages: may be large land disturbance and displacement of people, high methane emissions in shallow tropical reservoirs, disrupts downstream aquatic systems
(Source: Tennessee Valley Authority)
4. Geothermal is energy from within the earth that is stored in soil, underground rocks, and fluids in the earth’s mantle (the thick layer of hot, solid rock between the Earth's crust and its molten iron core; it makes up the bulk of the Earth, accounting for two-thirds of the planet's mass). Geothermal energy is produced by the slow decay of radioactive particles in the earth's core, a process that happens in all rocks. (The earth's core is hotter than the sun's surface.) People can use this heat as steam or as hot water to heat buildings or to generate electricity. Geothermal energy is a renewable energy source because the heat is continuously produced inside the earth.
The earth's crust is broken into pieces called plates. Magma comes close to the earth's surface near the edges of these plates, which is where many volcanoes occur. The lava that erupts from volcanoes is partly magma. Rocks and water absorb heat from magma deep underground. The rocks and water found deeper underground have the highest temperatures.
People around the world use geothermal energy to heat their homes and to produce electricity by drilling deep wells and pumping the hot underground water or steam to the surface. People can also use the stable temperatures near the surface of the earth to heat and cool buildings [United States Energy Administration (“Geothermal Explained”), 2017]. According to the Environmental Protection Agency, a well-designed geothermal heat-pump system is the most energy-efficient, reliable, environmentally clean, and cost-effective way to heat or cool a space (Miller and Spoolman, 2016). Miller and Spoolman’s analysis of geothermal energy:
Advantages: renewable, lower carbon dioxide emissions than fossil fuels, low-cost at favorable sites, medium net energy yield
Disadvantages: scarcity of suitable sites, high cost except at favorable sites, noise and some carbon dioxide emissions
5. Wind is energy from moving air. Wind is caused by the uneven heating of the earth's surface by the sun (for example, more solar energy at the equator and less at the poles). Because the earth's surface is made up of different types of land and water, the sun's heat is absorbed at different rates. One example of this uneven heating is the daily wind cycle.
(Source: Adapted from National Energy Education Development Project)
The United States has some of the best wind resources in the world, with enough potential energy to produce nearly 10 times the country's existing power needs. The Department of Energy estimates that wind farms in just three states – North Dakota, Kansas, and Texas – could more than meet the electricity needs of the lower 48 states. Wind energy is now one of the most cost-effective sources of new generation, competing with new installations of coal, gas and nuclear power. Its cost has dropped steadily over the past few years, as wind turbine technology has improved. Currently, over 400 American manufacturing plants build wind components, towers and blades.
Advantages: renewable, widely available, low electricity cost, little or no emissions of carbon dioxide and other air pollutants, easy to build and expand
Disadvantages: needs backup or storage system when low winds, low-level noise pollution, visual pollution for some people, can kill birds if not properly designed
6. Solar is energy from the sun. The sun has produced energy for billions of years and is the ultimate source for all of the energy sources and fuels that we use today. People have used the sun's rays (solar radiation) for thousands of years for warmth and to dry meat, fruit, and grains. Over time, people developed technologies to collect solar energy for heat and to convert it into electricity. Concentrated solar power uses mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine driving a generator.
Humans can capture solar energy directly from the sun in various ways, including:
Passive solar systems – for example, constructing homes with double- or triple-paned windows that get direct sunlight; the windows let in the sun’s energy and trap it inside, gradually raising the temperature.
Active solar systems are based on the same principles as passive systems except that they use a fluid (such as water) to absorb the heat. A solar collector stationed on the roof of a building hears the fluid and then pumps it through a system of pipes to heat the whole building.
Photovoltaic cells (solar panels) convert sunlight to electricity by using thin sheets of silicon which are easily attached to a roof.
We use solar thermal energy systems to heat water for use in homes, buildings, or swimming pools; heat the inside of homes, greenhouses, and other buildings; and heat fluids to high temperatures in solar thermal power plants. [United States Energy Administration (“Solar Explained”), 2017]. Solar installations in the United States exceed 3,100 megawatts, enough to power more than 630,000 homes. The solar industry employs more than 100, 000 Americans and is one of the fastest growing sectors in the U.S. Prices have dropped sharply in recent years, and the United States is now a net exporter of solar products.
Advantages: low land disturbance, very low emissions of carbon dioxide and other air pollutants, low cost for passive systems, medium net energy yield
Disadvantages: need access to sun 60% of daylight hours and/or backup for cloudy days, high installation and maintenance costs for active systems
Net Energy Yield from
Renewable Sources of Energy
For For For For
Electricity Heating Ind.Heat Trans.
Energy efficiency high high high high
Hydropower high ----- ----- -----
Geothermal medium medium ----- -----
Wind high ----- ----- -----
Solar low to medium medium low -----
Benefits of Renewable Sources of Energy
As discussed, the types of energy on which we depend have a profound effect on the natural environment and our society in general. Among the most important benefits of using renewable sources of energy are the following (Buy Clean Energy, 2017; Renewable Energy World, 2017):
1. A significant reduction in environmental harm and a significantly reduced contribution to climate change. Renewable energy technologies are clean sources of energy that have a much lower environmental impact than conventional energy technologies. Their use moves us away from dirty sources of energy that spew the greenhouse gases that produce climate change.
2. Energy Security. Renewable energy provides reliable power supplies and fuel diversification, which enhance energy security, lower risk of fuel spills, and reduce the need for imported fuels. Renewable energy also helps conserve the nation’s natural resources. There is an infinite supply of nonrenewable energy sources.
3. Economic Development. The renewable energy industry is more labor intensive than its fossil fuel counterpart, meaning on average greater job creation. The industry also creates positive ripple effects down to the renewable energy supply chain and unrelated businesses due to increased household incomes. Renewable energy investments are usually spent within the United States, frequently in the same state, and often in the same town. This means your energy dollars stay home to create jobs and fuel local economies, rather than going overseas.
4. Price Stability. Renewable energy sources such as wind, solar, hydro and geothermal do not entail fuel costs or require transportation, and therefore offer greater price stability. In fact, some electric utilities factor this into their retail electricity prices, exempting customers that buy renewables from certain fuel-related charges.
What Can Be Done
The starting points for doing something about the waste involved in use of nonrenewable energy sources is the same as with all of the environmental issues covered in this section of the website:
Become more knowledgeable about this issue.
Discuss this issue with others; learn from them and help them learn from you.
Reduce your own energy use and rely more on nonrenewable sources of energy. Check out your own “Carbon Footprint” at https://www3.epa.gov/carbon-footprint-calculator/.
Join forces with groups and organizations that are knowledgeable about environmental issues in general (BEAT!) and about this issue in particular. Organizations have greater access to scientific expertise, have larger budgets, have more contacts with the media, and have the force of combining many voices into one.
Advocate for policies that show understanding and respect for natural processes. Examples are educational programs and policies that encourage energy efficiency and greater use of renewable energy sources such as biomass, hydropower, geothermal power, wind power, and solar power by individuals, families, companies, and the government.
Advocate for government agencies and government leaders at all levels to conscientiously try to fulfill their responsibilities toward protection and conservation of the environment.
Examine the values and political position on this issue of candidates running for political office. Federal support for a strong Environmental Protection Agency is very important. Support for a meaningful Department of Environmental Quality in North Carolina is very important. Support by North Carolina’s governor and state legislature for taking a scientific approach to consideration of energy sources is absolutely critical. Look for candidates that emphasize the importance of environmental impact in making decisions about what to do or not do.
Lester R. 2008 Plan B 3.0: Mobilizing to Save Civilization. New York: W.W. Norton & Sons.
Buy Clean Energy. 2017 “Why Clean Energy is Important.”
Environmental Protection Agency. 2017 “Carbon Footprint Calculator.”
Green Tumble Editorial Team. 2017 “Harmful Effects of Nonrenewable Energy Sources on the Environment.”
G. Tyler Miller and Scott E. Spoolman. 2016 Environmental Science. Boston: Cengage Learning.
Maryruth Priebe. 2011 “Environmental Impacts from Nonrenewable Energy.”
Kwabena Stefan. 2017 “What Are the Effects of Non-Renewable Resources on Living Organisms?"
Renewable Energy World. 2017 “Types of Renewable Energy.”
United States Energy Information Sources. 2017 “Biomass Explained.”
United States Energy Information Sources. 2017 “Biomass Explained – Waste-to-Energy.”
United States Energy Information Sources. 2017 “Biomass Explained – Wood and Wood Waste.”
United States Energy Information Sources. 2017 “Coal Explained.”
United States Energy Information Sources. 2017 “Ethanol Explained.”
United States Energy Information Sources. 2017 “Ethanol and Biodiesel Explained.”
United States Energy Information Sources. 2017 “Geothermal Explained.”
United States Energy Information Sources. 2017 “Hydrocarbon Gas Liquids Explained.”
United States Energy Information Sources. 2017 “Hydropower Explained.”
United States Energy Information Sources. 2017 “Landfill Gas and Biogas Explained.”
United States Energy Information Sources. 2017 “Natural Gas Explained.”
United States Energy Information Sources. 2017 “Nuclear Explained.”
United States Energy Information Sources. 2017 “Oil: Crude and Petroleum Products Explained.”
United States Energy Information Sources. 2017 “Solar.”
United States Energy Information Sources. 2017 “U.S. Energy Facts Explained.”
United States Energy Information Sources. 2017 “Wind Explained.”
Read and See More About Energy Sources
Alternative Energy. 2017 “Wind Energy” www.altenergy.org/renewables/wind/
Information on wind power.
Energy4Me. 2017 “What is Energy?” www.energy4me.org/all-about-energy/what-is-energy/
Option to click on 11 renewable and nonrenewable energy sources for good information.
ListVerse. 2017 “Top Ten Renewable Energy Sources.” www.listverse.com/2009/05/01/top-10-renewable-energy-sources/
Brief review of some key information on 10 nonrewable energy sources.
North Carolina State University, Clean Energy Technology Center. 2017 “Health and Safety Impacts of Solar Photovoltaics (Solar Farms).”
A technical description of solar farms.
SourceWatch: “Environmental Impacts of Coal” 2017 www.sourcewatch.org/index.php/Environmental_impacts_of_coal
The many harms of burning coal.
Union of Concerned Scientists. 2017 “Benefits of Renewable Energy Use.”
Brief review of some key benefits of nonrenewable energy sources.
(Scholarly Article) Christoph Maurer, Christoph Cappel; and Tilmann E. Kuhn. 2017 “Progress in Building-Integrated Solar Thermal Systems.” Solar Energy 154:158-186.
Building-integrated solar systems can work more efficiently and at lower cost.
(Video) Department of Energy: “Solar Ready Vets: Preparing Veterans for the Solar Workforce”
Look into a program matching veterans and jobs in solar industry.
(Video) Bozeman: “Renewable Energy”
Discussion of several forms of renewable energy.
Sample of Scholarly Journals:
Energy and Environmental Science
Energy for Sustainable Development
Journal of Renewable and Sustainable Energy
Renewable and Sustainable Energy Reviews