AC/DC AND THE CANADIAN CONSPIRACY

Direct current (DC) flows one way all the time; in an alternating current (AC), the electrons quiver back and forth 60 times a second. Thomas Alva Edison used DC generators to supply the electric illumination that he had invented; but George Westinghouse saw the great advantages of AC.

Westinghouse won. AC can easily be stepped up to high voltages, or stepped down to low ones, with simple transformers in cases. High voltages are needed to transmit electric power with small losses over long distances, and they can then be stepped down for distribution to consumers.

But Westinghouse's victory was also morally just, for Edison's company had been using outrageous demagoguery in combatting AC. Edison himself waged the campaign on erroneous safety considerations, and that may have been an honest mistake; yet he must also have been well aware of what his employee Harold P. Brown, a sleazy Ralph-Nader type of the 1890s, was doing: scaring people by using AC to kill horses and other animals in the streets of New York, or presenting a Westinghouse AC generator to the governor of N.Y. for the first execution in the electric chair.

Both AC and DC have smaller losses in transmission at high voltages. AC is easier to step up to a high voltage, but once DC has been stepped up, it is cheaper and more reliable to transmit. That principle has not changed since Edison's and Westinghouse's time; what has changed is the technology for stepping up DC, and the need to transmit electric power over long distances.

One of the reasons why DC is cheaper for transmission is that it needs only two wires; AC needs three phases, and sometimes ground as well. And that, in turn, is one of the reasons why the towers carrying these conductors are very different: for the same reliability, an AC tower is roughly 50% larger, both in height and in the width of right-of-way.

Strictly speaking, DC cannot be stepped up to a higher voltage. It is AC that is stepped up in a transformer, and it is then converted to DC by "valves," so called because they let current flow only one way, converting AC to DC. Until the 1960s, this was done by electronic mercury tubes, large and very inefficient, for they would convert only part of the AC energy to DC, changing the rest to useless heat. But the semiconductor revolution did not bring only transistor radios: it also brought a valve called a thyristor, which can convert AC to DC with an efficiency in the high 90s.

It was the thyristor which reduced the cross-over point to a distance of a mere 500 km (310 miles), with one tenth that distance for underground and submarine cables. And it was the economic need to transmit and "wheel" power over long distances, described here last month, that led to a revival of high-voltage DC transmission lines. Six of these systems are now in operation in the US, and four more are under construction.

One of the latter is a line bringing almost 2,000 MW of hydropower from norther Quebec to New England. The line shows that two countries can cooperate in spite of governments whose oratory is full of free trade, but who in fact practice protectionism. The US has sandbagged Japan into volunteering to limit the export of cars that American consumers want, thus subsidizing Detroit's oversized and overpriced lemons. Canada has banned US magazines carrying advertising specifically directed at the Canadian market, thus protecting Canadian publishers from losing lucrative advertising revenue, which they would otherwise be condemned to attract by merit. Electric power from Canada is vehemently opposed by the (US) National Coal Assn. and other lobbies that find it easier to confront the competition with legislation than with a better product. Among such lobbies is the Edison Electric Institute, a fossilized antique which acts as the PR arm of US utilities. To counteract the Canadian "threat," it promotes a Neanderthal book implying that a Canadian conspiracy is using the acid rain issue to turn the US into its captive electric-power market [AtE May 85].

Here is one of the rules guaranteeing success in both politics and business: preach free trade and slap on the tariffs.