What are some traditional energy sources?
For the past century, the U.S. has primarily relied on fossil fuels, which include coal, natural gas, and petroleum products to be the major supplier of energy to meet the needs of the people. The relatively low cost of fossil fuels and their ease of use has made them the energy source of choice with most people. However, since fossil fuels are a limited, nonrenewable resource and are often associated with some levels of environmental damage, the need to find and use alternative energy sources has accelerated over the past few decades.
Coal
Coal is mainly composed of carbon in the solid form. Coal has a relatively low cost, high energy content, and when combined with oxygen in the combustion process produces heat. The heat is used to convert water to steam that spins turbines that generate electrical energy. The U.S. has abundant reserves of coal. A downside of coal combustion is the production of waste products, such as carbon dioxide and sulfur oxides that can contaminate the environment.
Natural gas
Two hydrocarbons, methane and ethane, are the major parts of natural gas found in homes. These hydrocarbons can be combusted and produce large amounts of heat. Many U.S. power plants, home water heaters, and home heating systems rely on natural gas to supply their energy needs. The U.S. also has large reserves of natural gas that can provide low-cost energy. Natural gas generally burns cleaner than coal and produces fewer waste products; however, significant amounts of carbon dioxide are released during the combustion process.
What are some alternative energy sources?
A number of alternative sources have been suggested and researched to supply the energy needs of communities. These include nuclear power plants, wind turbines, solar cells, geothermal systems, biomass plants, hydroelectric, and tidal variations power systems. All of these systems have both advantages and disadvantages that must be compared against traditional energy sources.
Nuclear reactions
Nuclear power is an alternative to traditional fossil fuels as an energy resource. Nuclear power is produced using fission reactions, where a larger atom is changed into two or more smaller atoms. This process releases large amounts of heat, which they can be used to produce electrical power in the same manner as the fossil fuels. Vast quantities of energy can be released from relatively small amounts of fission materials. However, high construction and maintenance costs of facilities and the need for sophisticated waste disposal methods make this form of energy production less desirable.
Wind turbines
Wind power relies on the unlimited natural resource that blows across almost every location on Earth: wind. Wind turbines use the energy associated with moving air to turn a large blade, which in turn spins a generator that makes electrical energy. Although this energy source appears to be free because wind is an unlimited natural resource, high costs are associated with the construction and maintenance of the turbines. Many people also object to the wind turbines being placed in their area due to their unsightly appearance and the noise created by the spinning blade.
Solar Cells
Photovoltaic cells are often referred to as solar cells. Solar cells directly convert sunlight into electrical energy. Since sunlight is an unlimited resource, solar cells are a relatively inexpensive way to produce electrical energy. The cost of making solar cells has dropped significantly over the past couple of decades, and has reached a point where many U.S. homes supplement their energy needs using solar power. Current limitations of solar power include the large collection areas required for the solar panels, and solar cells located in regions that have limited sunny days may not operate at efficiencies high enough to supply energy demands.
Geothermal
Vast pockets of hot materials lie below the surface of Earth. Liquid water that is trapped in rock adjoining these hot regions is heated and converted to steam. These steam reservoirs can be tapped and the steam used to spin turbines, which in turn generate electricity. Two major problems associated with using geothermal energy are that not all areas have geothermal pockets that can be tapped, and often many of the regions that do offer access are located great distances from the populations with the electricity needs. Power transmission lines that run great lengths often result in large energy "losses" along the line when the desired electrical energy is converted to waste heat.
Biomass
Biomass power plants produce energy via the combustion of typical yard waste, trash, and timber sources. These materials are burned to make heat that converts liquid water to steam and is used to spin a turbine to generate electricity. Since timber is a renewable, limited resource, these plants can operate long-term without having to worry about running out of fuel. Disadvantages of these plants include environmental and noise pollution.
Hydroelectric
Moving water can be used to spin turbines to generate electricity. The faster the water moves, the more electricity can be generated by the turbines. For this reason, hydroelectric power plants are often located in areas where water can be stored in lakes and then allowed to fall to a river at a much lower level than the storage lake. Since larger amounts of moving water are needed to supply the movement of the turbines, hydroelectric power plants are limited in their geographic placement.
How is electricity transmitted to homes?
All the poles and wires you see along the highway are called the electrical transmission and distribution system that bring electrical energy to homes. Today, generating stations all across the country are connected to each other through the electrical system (sometimes called the "power grid"). If one generating station can't produce enough electricity to run all the air conditioners or heaters when it's hot or cold, another generating station can send some where it's needed.
Most electricity is produced at power companies by generators. The current is sent through transformers to increase the voltage to push the power long distances. The electrical charge goes through high-voltage transmission lines that stretch across the country. The current reaches a substation, where the voltage is lowered so it can be sent on smaller power lines. The moving charges travels through distribution lines to your neighborhood. Smaller transformers reduce the voltage again to make the power safe to use in homes. These smaller transformers may be mounted on the poles, or sitting on the ground (they’re the big green boxes, called pad mount transformers) where the electrical energy finally enters a home.
How much energy is lost in transmission and distributions to homes?
The U.S. Energy Information Administration (EIA) estimates that electricity transmission and distribution (T&D) losses equaled about 5% of the electricity transmitted and distributed in the United States in 2016 through 2020. The energy loss is due primarily to resistance in the wires and systems that move the electricity from the source to the homes.
Given the same material wire, the longer the wire the greater the resistance. Also, a smaller diameter wire has more resistance than a greater diameter wire. Th greater the resistance in a wire, the greater the amount of heat energy conversion in the wire.
What is a transformer?
A transformer is a device used in electrical circuits to change the voltage in an Alternating Current (AC) electrical supply. A transformer consists of two parallel metal bars, each with wire wrapped around the bars (called windings). A transformer moves electrical energy from one circuit to another with the help of mutual induction between the primary and secondary windings. The voltage in a circuit can be increased or decreased depending upon the need.
A step-up transformer increases the output voltage in relation to the input voltage. In this type of transformer, the number of turns on the secondary winding is more than the number of turns on the primary winding. A step-down transformer decreases the output voltage in relation to the input voltage. This type of a transformer is opposite of a step-up, with the number of turns on the secondary winding being less than the number of turns on the primary winding.
The need for more electricity continues to grow as people demand a greater number of appliances and devices that use energy. City officials face difficult decisions as to which type of energy source should be used to supply a town’s electrical energy needs. All energy sources have benefits and drawbacks associated with their use. Which energy source would you choose to supply your city’s electricity needs?
