At one time, solar, wind, wood, and hydro power - and all the other renewable energy industries - took on the character of a social cause. They inspired as much talk of ethical virtue and the future of the planet as of profit margins.
The talk died out as the oil glut set in, recession descended, and a more conservative president moved into the White House.
But the infant industries are alive and growing with what is largely a new cast of characters - including major corporations and financial institutions.
And while many alternative energy companies have fallen by the wayside in the early 1980s, others are doing extremely well.
Many of the companies making an appearance this week at the first Renewable Energy Technologies Symposium and Exposition are five years old or younger, and are just beginning to come out of the research and development stages and seriously market their products.
The people here have the look of the marketing and engineering worlds, rather than New Age idealists. Few could think of anyone among the more than 200 companies here that had been in the business as long as eight years.
''I'm here to dispel the notion that renewable energy is suffering from hard times,'' says Christopher Flavin, a researcher at Worldwatch Institute. Unlike the synfuels industry, which lost its momentum as oil prices fell, renewable energy industries have grown steadily, he says.
And in the past few years, Mr. Flavin adds, the private sector has taken over the leadership role from the government. Taken all together, he notes, renewable energy companies have outperformed the Wall Street bull market in general in the past year.
Investment banker Philip Huyck with First Boston Corporation is more skeptical: ''I guess I'm not quite so sanguine.'' The young industries are still not stable enough to win the full acceptance of big financial institutions - not least because most still rely on imperiled federal income tax credits for their survival, he says. Those tax credits help homeowners afford the installation of energy-saving technology.
The late 1970s were boom years for renewable energy. The energy crisis and the support of the Carter White House brought scores of new entrepreneurs into the business.
Some were good, some weren't, says Mr. Huyck. The drop in oil prices and the budget-cutting of the Reagan White House shook many of them out.
''Nobody ever says they're getting out of the business,'' Huyck says. ''They just go back for further study.''
Those who have succeeded in the business, though, are forging stronger ties to the business establihsment. Most photovoltaic solar-power companies have been bought up by major oil companies as they have grown to a significant size. Utilities like Southern California Edison have become a major market for renewable energy technology. And increasingly, renewable energy companies have gone to the stock market for capital.
Huyck says he is ''positively messianic'' about the future of these industries, but he stresses the need for stability and cautious, balanced forecasts. ''Too high a projection is as bad as too low,'' he says, since boom forecasts lure too many weak products and businesses into the field.
As renewable energy becomes more big-businesslike, no longer the domain solely of environmentalists and inventors, notes Mr. Flavin of Worldwatch, ''a lot more conservative Republicans are moving in.''
So support for renewable energy has grown in the traditional business community and the public utilities, he explains, while its potential as an alternative to other energy sources, such as nuclear power, is still frequently derided.
Flavin says 18 percent of the world's energy was supplied by renewable sources last year, and its share will grow to at least 26 percent by the end of the century.
Many of the firms here are off to a fast start. Chronar Corporation, for example, which manufactures an advanced type of thin-film solar cell, has watched its stock price multiply almost tenfold since it was issued in August 1981 - mostly in the last year.