Power Struggle

1880s solution - In 1879, only 11 years before my father was born, a direct current electric central station in downtown San Francisco was thought to be the optimal power supply system. It replaced on-site direct current ("DC") generators powering arc lights. It was the first central station power system, beating even Edison’s far better publicized Pearl Street station. Edison’s central station commenced service three years later in 1882 in the Big Apple. His central station also supplied DC but it supplied electric energy for incandescent light bulbs instead of arc lights.

Customers of Edison's central station in New York City at 255-257 Pearl Street could receive DC service for their light bulbs only if they were located within a half mile of the station. The DC technology could transmit electric energy only short distances at the low voltages safe for customers’ use. That is because it was very difficult and expensive to vary the voltage of DC electric power after it left the generator. You could transmit DC Power at a high voltage – using fewer amperes and thinner copper wires – and then step it down to a safe voltage at the customer’s meter with a high voltage DC motor and a low voltage DC generator, but it would be terribly expensive to do so.

Another DC central station was soon operating in London to serve loads within a half mile of No. 57 Holborn Viaduct. Gaslight company exclusive rights to dig in the streets prevented Edison from digging up the streets in London to lay his distribution feeders, but he discovered that the Holborn Viaduct had been equipped with channels and raceways in which the wires could easily be installed, much to the dismay of the gas companies.

Soon thereafter alternating current ("AC") central stations commenced operation in the US since when using alternating current, electric energy could be transmitted at high voltage over thin copper wires and stepped down to low voltage with an inexpensive transformer. Its deliveries were no longer limited to a half mile – electric energy could be transmitted economically for several miles. The higher the voltage, the further it could economically be transmitted. At today’s extra high voltage, energy can be transmitted for hundreds of miles.

I show here how the ability to transmit electric energy economically for many miles, coupled with the development of steam turbine-generators with great scale economies, led to a system of ever larger steam turbine generators fueled with coal or nuclear fuel supplying our base load electric energy requirements. Their sizes reached as high as 600,000 to 1.4 million kilowatts.

Why was this desirable? It was because these giant generating units could generate with far greater fuel efficiency and could be constructed for far lower cost per kilowatt. That was only advantage in generating power in one place and delivering it to another place many miles away to serve a load there. There are many disadvantages.

With distribution lines one could collect load at many points in a load center to be served from a single distribution substation, and with transmission lines from that substation to a generating unit one could collect load at many load centers. These remote loads could be served from that giant generating unit which enjoyed scale economies of fuel efficiency and cost per kilowatt of capacity. These considerations dominated power supply planning for the next one hundred years.

Then over the next twenty years when gas prices were only 40% to 50% higher than the price of coal per million BTUs, the aero-derivative gas combustion turbine and combined cycle system with technology borrowed from the airline industry took the lead in supplying base load energy. These aero-derivatives and combined cycles could generate even more efficiently in somewhat smaller unit sizes, 50,000 kW to 400,000 kW but still very large compared to typical individual loads or even the size of a typical load centers.

Power and Its Problems
The United States, after 120 years, now has the largest power system in the world, with a generating capacity of some 900,000,000 kilowatts with an impact on productivity that makes our standard of living among the best in the world. But it is beset with problems.

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