This article highlights that the creation of efficient electric appliances using cheap electricity has enabled us to enjoy healthier and more bountiful lives. Since electric power results from the conversion of energy resources in an electric power generating plant, those resources must be adequate and available at low cost at the plant site. Mechanical engineers developed the machinery for coal mining, for coal transportation, and for bulk coal handling. GE and Westinghouse made early contributions starting in electric generator and electric motor development. The US electric utility industry has been mandated by several states to sell all or a large portion of its generating plants. Independent power generators are building new combined-cycle units in selected market regions. Mergers and acquisitions of electric utilities are continuing to increase the size of parent company operations. Mechanical engineers have developed relatively low-cost electric power generation technology through the 20th century, enabling the United States to maintain its world economic leadership and standard of living.
At the beginning of the past century, electric power was expensive, 20 cents a kilowatt-hour or higher, and available only in cities. It was used primarily for lighting streets and buildings, for powering electric tramways (streetcars), and early-technology motors in manufacturing operations. Few electric appliances were available for homes, and the cost of electric power was beyond the means of most families.
Throughout the 20th century, mechanical engineers continuously improved the technology and efficiency of energy conversion that enabled the power generation industry to provide inexpensive electricity for a growing U.S. economy. The results of their ingenuity have been the bedrock of U.S. manufacturing competitiveness in the world economy. In addition, the creation of efficient electric appliances using cheap electricity has enabled us to enjoy healthier and more bountiful lives.
Since electric power results from the conversion of energy resources in an electric power generating plant, those resources must be adequate and available at low cost at the plant site. Mechanical engineers developed the machinery for coal mining, for coal transportation, and for bulk coal handling. Mechanical engineers designed the oil and gas drilling rigs, the pumping stations, and the pipelines to the plant sites. In the last 40 years of the century, mechanical engineers designed and developed our nuclear power plants and began developing the technology for future economical and renewable energy power generation.
In the early 1900s, cogeneration of process steam and electricity at large industrial facilities was widespread, because the electric power systems were not yet extensive and electric utility power costs were not competitive. Mechanical engineers designed and built these cogen plants, based on more efficient equipment each year, at companies like Dow Chemical Co.
The history of U.S. electric power generation in the 20th century has been defined by three concerns: cost, technology, and reliability. In the last three decades, the industry has been significantly affected by escalating government regulations on emissions at fossil-fuelburning power plants and on nuclear power plants for protecting public safety. These regulations provided challenges for mechanical engineers, and the additional systems required have been the primary cause of reduced fossil plant conversion efficiencies and the higher capital costs of new generating plants from 1970 to 1999.
Until about 1970, generating costs overruled other considerations, such as efficiency and plant emissions. The economic exception in the first 50 years was large hydroelectric generating plants built by federal agencies. The projects provided additional benefits, such as flood control, water storage, and improved navigation.
Reliability of power generation, and the transmission system, was a major achievement throughout this century.
In the early 20th century, electric power was generated by cogeneration plants in industry, by a few federal hydropower plants, and by electric utilities. From 1900 through 1970, electric power generation costs decreased every decade, and electric power generating capacity in the United States doubled every eight to 12 years.
In 1896, the Niagara Falls hydroelectric plant started operation with three units, each of 5,000-hp rating—the largest station at that time. It delivered electricity to Buffalo, N.Y., at 2,350 volts for transmission with a 25 hertz ac. In 1900, the typical electric utility plant was coal- or oil-fired, generating steam for reciprocating engines that drove electric generators. Steam turbines were soon to replace steam engines for ac power generation. In 1903, a 5 MW Curtis steam turbine began operating at a; Commonwealth Edison power plant. From 1900 to 1920, steam turbine generators typically operated at 1,200 rpm with unit capacity up to 62 MW; from 1920 to 1935 at 1,800 rpm with unit capacity to 200 MW; from 1935 to 1953 at 3,600 rpm. By the 1980s, large coal-fired units with cross-compound turbine generators and nuclear power units had reached 1,300 MW capacity.
Electric utilities were founded and grew rapidly in the early decades of the 20th century. A few electric utility holding companies were in existence. The Stone & Webster group of utilities, the Ebasco group, and the Commonwealth and Southern group were growing.
Sam Insull built a huge family of electric utilities from Commonwealth Edison in Chicago. He pioneered continual rate cuts and encouraged rate regulation after 1907. His company owned and operated electric utilities in several states. The parent company also owned subsidiary engineering and construction companies and other firms, which supplied services and products to the electric utilities in the group.
The Public Utility Holding Company Act, or PUHCA, in 1935 caused the breakup of private electric utilities into individual stock companies by 1955.
The Tennessee Valley Authority was created in 1933 to develop the Tennessee River resources, including flood control and hydroelectric power generation. It acquired existing electric power plants and small electric utilities in the next 20 years, and built large hydroelectric plants and transmission systems. The TVA built its first coal-fired steam electric plant in 1949 and its first nuclear power plant in the 1960s. The Rural Electric Association was established in 1936 to electrify remote farms.
The Bureau of Reclamation, Bonneville, and other federal agencies built large hydroelectric generating plants through the middle part of the century. The best of the large hydro energy resources had been developed by about 1970. Further development of hydroelectric generation has been restricted by new environmental laws that enabled opposition by environmental activist organizations.
In 1900, the electric power plants converted the energy resources of hydro, coal, and oil to produce electric power in the United States. By 1955, 53 percent of power generation came from coal, 6 percent from oil, 18 percent from natural gas, and 22 percent from hydro. The United States was producing 42 percent of the world’s kilowatt-hours. In 1998, primary power generation resources converted to electricity were coal, accounting for 52 percent; nuclear, 19 percent; natural gas, 15 percent; oil, 4 percent, and hydro, 9 percent.
Even Better Boilers
While mechanical engineers in the electric utilities achieved improvements in operating their plants and continual upgrades in equipment and systems, they were reliant on the technology developments of major equipment suppliers. In the early years of the 20th century, the leading companies in supplying this technology included Babcock & Wilcox, General Electric, and Westinghouse.
B&W had been building and supplying steam boilers for a decade before the birth of electric power generation. In 1902, B&W supplied eight 508-hp steam boilers, rated at 180 psig and 530°F, for the Commonwealth Edison Fisk Station, the first public utility plant operated entirely with steam turbines, with a capacity of 5 MW each. The first ASME Boiler Code was established in 1915. By the time the 1960s began, B&W and other boiler suppliers were capable of delivering large steam boilers at 5,000 psig and 1,200°F with attendant high efficiency for electric power production.
GE and Westinghouse made early contributions starting in electric generator and electric motor development. With the ac versus dc choice for power generation resolved before 1900, steam turbines began to replace steam engines to drive 1,200-rpm electric generators.
Sir Charles Parsons, in England, had built a 10-hp steam turbine in 1884. Carl De Laval, in Sweden, developed and built a 15-hp steam turbine in 1892. During the 1890s, further steam turbine improvements were credited to C.E.A. Rateau in France and Charles Curtis in the United States. Shortly after 1900, the steam turbine replaced the steam engine, and the emerging technology was acquired by General Electric and Westinghouse, which could then supply a 1,200-rpm steam turbinegenerator package.
The major steam turbine-electric generator suppliers in 1950 in the United States were GE, Westinghouse, and Allis Chalmers. Mechanical engineers at these companies competitively developed the materials for steam turbines and more efficient machines in growing unit sizes to gain the benefits of economy of size for their electric utility customers. New leaps in size and technology had demonstrated they were reliable and could be maintained at acceptable cost before commercial acceptance.
Gas turbine prime mover technology has been developed for decades, primarily for application in aircraft. Gas turbine units up to 150 MW were available by 1990, but economically limited by the economy of scale against the large turbine-generator units being built at that time. By 1990, the impact of federal regulatory requirements, with the cost of delays in construction, caused the power generating firms to favor the economic attractiveness of natural gas-fired turbines in a combined cycle with waste heat boilers and steam turbines. By 1999, these were the economic choice for new plants due to higher efficiency, low capital cost, and relatively short permitting and construction schedules.
With the end of World War II, government programs in national laboratories and industrial contractors began to develop controllable nuclear fission reactors, which produced waste heat that was discarded to the atmosphere. In December 1951, the liquid metal-cooled Experimental Breeder Reactor No. 1 in Arco, Idaho, first used this energy to produce steam and electricity, and nuclear power was born.
From Subs to Power Plants
Nuclear power technology development proceeded rapidly in the 1950s through the Navy nuclear propulsion programs directed by Admiral Hyman G. Rickover. The Nautilus submarine went to sea powered by nuclear energy in 1955. Congress authorized the Atoms for Peace program and the formation of the Atomic Energy Commission that same year. Under Rickover’s direction, the Shippingport, Pa., demonstration nuclear power plant was built using the Nautilus technology to generate electricity for a utility, Duquesne Light Co., and started up in 1958. In the mid- 1950s, four groups of electric utilities, manufacturers, and architect-engineer firms established offices to study the feasibility of commercial nuclear power.
The utility groups’ conceptual designs for nuclear power plants were supported by AEC-sponsored research and development programs at the national laboratories, at universities, and at manufacturers’ R&D sites. Utilities started up their early nuclear power demonstration plants from 1960 through ’63. They included Yankee-Rowe in Massachusetts, Dresden No. 1 in Illinois, Fermi I in Michigan, and Hallam in Nebraska.
Larger nuclear reactor plants were contracted in the mid-1960s by the competitive nuclear steam supply vendors in plants designed and constructed by the major engineer-constructors. General Electric, Westinghouse, Combustion Engineering, and Babcock & Wilcox were taking firm price orders for nuclear reactor steam supply systems up to approximately 600 MW in capacity. By 1974, nuclear steam supply systems were ordered up to 1,300 MW capacity each. More than 200 nuclear power plants were operating, under construction, or under contract in the United States by the end of 1974. Today, only 103 commercial nuclear power generating units are in operation in the 50 states.
What happened to the growth of nuclear power in the country? Several factors came together in the 1970s to rapidly increase the capital cost of nuclear power plants. The capital cost of commercial nuclear plants completed by the early 1970s was typically $250 to $300 per kilowatt of capacity. Inflation caused all U.S. costs to rise sharply in the 1970s, including the cost of nuclear power plant equipment.
Probably the greatest impact on nuclear plant costs and construction schedules was the growth of federal regulatory requirements of the AEC and, later, the new Nuclear Regulatory Commission and the Environmental Protection Agency. The early commercial nuclear power plants were built under strict industry codes and standards, and minimal federal regulation. The cost and schedule control had been predictable. The few permits for construction were readily obtained in months, not years. Most of these plants are still in operation.
In the late 1970s, the EPA and NRC regulatory requirements escalated sharply, resulting in costly permitting, construction delays, retrofits to construction in progress, and design changes. Mechanical engineers rose to the challenge, but were overwhelmed by these new changing regulatory requirements. Utilities canceled orders for about 100 nuclear generating units in the United States because of the difficulty in obtaining the necessary permits, and unpredictable capital costs or schedules to complete construction.
The regulatory laws passed by Congress enabled nuclear power opponents to intervene in court in licensing proceedings for construction permits and for operating licenses. These interventions were successful in delaying nearly all projects after 1975—thus increasing capital costs substantially.
Similar escalating regulatory requirements affected the large coal-fired plants during this period.
The 1979 nuclear accident at Three Mile Island badly damaged the public acceptance of nuclear power plants in the United States. Although there was no public exposure to radiation from this accident, the public was fearful, and the NRC regulatory response escalated the required changes to plants under construction. Nuclear plants completed and put into operation after 1980 had a capital cost of 1,000 to 2,000 percent of those completed by the early 1970s.
In 1999, new electric power generating plants in the United States were nearly all natural gas-fired combined-cycle units. No coal-fired power plants, hydroelectric plants, or nuclear power plants are being constructed. A few windmill generating parks are under construction. R&D continues on solar- powered generation and fuel cell development. No renewable energy generating plants are economically competitive in large power systems as yet.
The U.S. domestic energy resources of coal and uranium remain plentiful for the next century. Some hydroelectric resources could be developed. All three of these domestic resources could be cheap electric power sources, but are hampered by massive regulatory burdens that would incur large capital costs and delays in construction. Natural gas resources may be limited in a few decades. Further technological breakthroughs will be needed to make other renewable energy resources competitive at current electric power market prices.
The U.S. electric utility industry has been mandated by several states to sell all or a large portion of its generating plants. Independent power generators are building new combined-cycle units in selected market regions. Mergers and acquisitions of electric utilities are continuing to increase the size of parent company operations.
Mechanical engineers have developed relatively low-cost electric power generation technology through the 20th century, enabling the United States to maintain its world economic leadership and standard of living. We will continue to solve the challenges of the coming century.