Obama’s Personal Green Initiatives Misleading

Hello Teresa,

I was reading the Mar/Apr/2010 issue of ELP and was particularly interested in the commentary “Uncovered: 100 Years of Electricity History.”

What was somewhat surprising to me is in the last paragraph that states that Obama owns a hybrid Ford Escape. It was my understanding that as a senator for the state of Illinois, he actually drove a Chrysler 300 and sold this car just before the campaign, so the article is somewhat misleading about the president’s personal green initiatives.

Gregg S. Paulson, P.E.
Manassas, Va.

Note from editor: Hi, Gregg. My research indicates that President Obama owned a Chrysler 300 when he was a senator and traded it for a hybrid Ford Escape in late 2007 when he was a presidential candidate. I believe he still owns the Escape—at least he did in late 2009. Of course, I doubt that he does much driving these days and instead rides in an armored Cadillac that probably isn’t too fuel-efficient. Thanks for reading the magazine.

Don’t Forget Tesla, Westinghouse, Subway, Delray

Teresa,

I was stimulated by your editorial on 100 years of electricity. Your reference to the Pearl Street station in New York reminds me that the first power plant in Detroit, Station A, is preserved in The Henry Ford (also known as the Henry Ford Museum and Greenfield Village—it seems to have an identity problem) in a two-thirds-scale operating plant. It has horizontal tube boilers like a steam locomotive and piston engines-driven dynamos via leather belts on the second floor.

Well, 100 years ago we were a nation struggling with the technology of AC vs. DC distribution. We learned from Pearl Street that DC could power only a square mile or so and that nobody wanted a coal-fired power plant every square mile. We harnessed Nikola Tesla’s alternating current via George Westinghouse & Co. to transmit “bulk” power to rotary converter (motor generator set) substations to transform it back to DC for distribution.

Tesla’s AC power was first demonstrated at Niagara Falls,* but it was two-phase and 25 Hz. Tesla developed AC induction motors, single phase, but they needed a second phase 90 degrees out of phase to start. Twenty-five Hz just happened to be a suitable frequency for water-powered turbine generators. It also worked with reciprocating engine power generators. Neither of these prime movers wanted to run above 100 rpm. The flicker of 25 Hz was almost imperceptible to humans. Not to say 25 Hz was adopted widely. Europe likes 20 and even 16 Hz.

The boldest move in the electric industry was really powering the New York subway system. It needed large blocks of 600-volt DC to power the third rails, and the problem of how to distribute that power led to one of the first three-phase systems to be built. Tesla discovered that a three-phase system with voltages displaced by 120 degrees was a mathematical stroke of genius. It was far superior to the two-phase system because it could be balanced out, thus distributing load evenly between phases. But the New York subway system also was unique in that it distributed power at the unheard of voltage of 11,000 volts. The converter substations transformed that to 4,800 volts to feed rotary converters to supply track power.

So what brought us to 60 Hz? The answer is the steam turbine. Detroit Edison installed some of the first steam turbines in their Delray plant around 1910—it could have been as early as 1904—but they weren’t like any turbine you might have seen. They more closely resembled hydroelectric turbines with vertical shafts. The turbine exhausted to a condenser below, and the generator sat on top, just like a hydro plant. But a steam turbine is large and inefficient at slow speed. Generators are massive at slow speed, so the solution is to increase the speed, hence three-phase, 60-Hz, six-pole generators. Still, six-pole generators are pretty slow.

The next-generation turbo generator was reconfigured with a horizontal shaft, which overcame the weight limits of placing the generator above the turbine and allowed for much larger generators. Detroit’s new generators were 15-megavolt amperes (MVA), later 30-MVA, 1,800-rpm machines. This was by 1915. The Delray plant was flattened and a new one built with horizontal shaft machines.

And so we have the basis of what we have today: It all started in the technological revolution, nearly 100 years ago when steam was king and electricity was just in its adolescence.

*The first power plant in Niagara Falls fell into the river, but some rotary converters continued 25-Hz service for many years. Just recently that service was discontinued. The city of Philadelphia had two-phase 2,400 distribution until recently. Amtrak still has extensive 25-Hz, 11-kV, catenary power along the eastern seaboard.

Jim Evans

Note from editor: The Henry Ford in Dearborn, Mich., is also known as the Edison Institute, not to be confused with the Edison Electric Institute in Washington, D.C.