Q. Present and Future Trends in power systems?

According to the Edison Electric Institute, electricity's share of U.S. primary energy was almost 36% in 1989, and it is likely to reach 46% by the year 2010. The growth rate in the use of electric energy in the United States is projected to increase by about 2.4% per year for the near future, in spite of conservation practices, more efficient use of electricity, and a slackening population growth. One should also be aware of large growth of power systems internationally.

Because of the large amount of U.S. coal reserves, there is the continuing shift away from the use of gas and oil and toward increasing use of coal. Unless the construction time and cost per kW can be reduced significantly, no new nuclear units will be commissioned. Also, safety concerns seemto demand inherently safe reactor designs with standardized,modular construction of nuclear units. Since the major U.S. hydroelectric sites (except in Alaska) have been fully developed, one can foresee a trend for continuing percentage decline in hydroelectric energy generation.

By the year 2000, the total U.S. generating capacity has reached 817 GW (1GW=1000MW) and continues to grow. Current lead times of about a decade for the construction and licensing of large coal-fired units may cause insufficient reserve margins in some regions of the United States. As of 1989, U.S. transmission systems consisted of about 146,600 circuit-miles of high- voltage transmission. During the 1990s, additions have totalled up to 13,350 circuit-miles, which include 230-kV, 345-kV, and 500-kV lines. Because of the right-of-way costs, the possibility of six-phase transmission (instead of the current three-phase transmission) is being looked into. U.S. distribution-network construction is expected to increase over the next decade. The older 2.4-, 4.1-, and 5-kV distribution systems are being converted to 12 or 15 kV. Higher distribution voltages such as 25 and 34.5 kV are also contemplated. Recently some concern has surfaced about the effect of electromagnetic waves on the human and animal environment. The result of this remains to be seen.