Electricity energy transmission
Electricity energy transmission refers to the process of transporting electrical energy from power generation sites to consumers through a network of transmission lines. As electricity is not a primary energy source but rather a means of transferring energy, effective transmission systems are essential for delivering power where it is needed. Following the generation of electricity at power plants, high-voltage transmission lines carry this energy over long distances to substations, where transformers convert it into lower voltages suitable for residential and commercial use.
The systems in place for electric transmission can be categorized into long-distance, subtransmission, and merchant transmission. Long-distance transmission is particularly efficient and cost-effective, allowing cities to source electricity from far-off suppliers if it proves cheaper than local generation. Subtransmission operates at lower voltages and connects smaller substations, while merchant transmission involves third-party companies constructing and operating lines, fostering competition within the grid.
Given the inability to store electrical energy in large quantities, maintaining a balance between supply and demand is crucial to prevent power outages and blackouts. Overall, advancements in transmission technology continue to evolve, aiming to enhance the efficiency and reliability of electricity distribution worldwide.
Subject Terms
Electricity energy transmission
Summary: Electrical energy (commonly called electricity), though a secondary form of power, remains the most important energy. Production and consumption of electricity involves generation, transmission, and distribution.
Electricity is not a primary energy source in and of itself but is rather a means of transferring energy from a source to a use in the form of work. Central to the use of electricity, therefore, is its transmission, along with its production and consumption. Benjamin Franklin first discovered that, to generate electricity or for electrical energy to exist at all, there must be a conductor or a circuit that will enable the transfer of the energy. Electrical energy is said to only occur when electric charges are moving or changing position from one element or object to another. After electricity is produced at power plants, it has to get to the customers who use the electricity.
Today, most of the world’s cities are crisscrossed with transmission lines that transfer electricity through transformers developed by George Westinghouse. The transformer has allowed electricity to be efficiently transmitted over both short and long distances.
What Is Electric Transmission?
Electric transmission of energy, otherwise known as high-voltage electric transmission, is generally seen as mass movement or bulk transfer of electricity through transmission lines, from power-generating plants to substations, the latter usually situated near population centers. In the United Kingdom, electric transmission lines are interconnected and referred to as the national grid; such networks are known as power grids in the United States. North America has three major grids: the Western Interconnection, the Eastern Interconnection, and the Texas Interconnection (operated by the Electric Reliability Council of Texas, ERCOT).
Electricity is transmitted at high voltages (110 kilovolts or greater) to reduce the energy lost in long-distance transmission. It is important to note, however, that because electrical energy, for the most part, cannot be stored, a more sophisticated system of control is vital to ensuring a balance between supply and demand. Failure to do this could result not only in national electricity failure but also in regional blackouts (such as those that occurred in 1965, 1977, and 2003 in the northeastern United States).
Electric Transmission Systems
There are three types of electric transmission systems: long-distance, subtransmission, and merchant.
Long-distance transmission of electricity across thousands of miles is cheap and efficient, with costs of $0.005 to $0.02 per kilowatt-hour (compared to annual averaged large-producer costs of $0.01 to $0.025 per kilowatt-hour, retail rates upwards of $0.10 per kilowatt-hour, and much more for instantaneous supply at unpredicted, highest-demand moments). Thus, it can be less expensive to use distant suppliers than it is to use local sources; for example, New York City buys much of its electricity from Canada. Multiple local sources, however—even if more expensive and infrequently used—can make the transmission grid more tolerant of weather and other disasters that can disconnect distant suppliers. When electricity travels long distances, it is better to have it at higher voltages; electricity can be transferred more efficiently at high voltages. Transmission lines are made of copper or aluminum in long, thick cables; these are materials that have low electrical resistance. The lower the resistance, the less heat is generated during transmission, and hence, less energy is lost along the way. High-voltage transmission lines carry electricity long distances to a substation. The power lines go into substations near businesses, factories, and homes. There, transformers change the very high-voltage electricity back into lower-voltage electricity that can be used for the appliances and devices at these locations.
Subtransmission is part of an electric power transmission system that runs at relatively lower voltages. It is uneconomical to connect all distribution substations to the high main transmission voltage because the equipment is larger and more expensive. Typically, only larger substations connect to this high voltage. It is stepped down and sent to smaller substations in towns and neighborhoods. Subtransmission circuits are usually arranged in loops so that a single-line failure does not cut off service to a large number of customers for more than a short time. Although subtransmission circuits are usually carried on overhead lines, buried cables may be used in urban areas.
Merchant transmission refers to an arrangement in which a third party constructs and operates electric transmission lines through the franchise area of an unrelated utility. Advocates of merchant transmission claim that this activity creates competition to construct the most efficient and lowest-cost additions to the transmission grid. Merchant transmission projects typically involve direct current (DC) lines because it is easier to limit flows to paying customers. Merchant transmission remains a work in progress, so there are few examples, but some include the Neptune RTS transmission line from Sayreville, New Jersey and New York; ITC Holdings’ transmission system in the American Midwest; Path 15 in California; and the Bass link between Tasmania and Victoria in Australia.
As C. L. DeMarco has observed, in electric transmission systems, much relatively new technology has reached reasonable maturity since the start of the 21st century. As of the mid-2020s, the future seemed bright, as these new technologies were waiting in the wings to offer greater capability to utilize grid resources to satisfy the world's electricity needs.
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