New technology, economics convert old dams into hydropower plants

"Cash cows" are what some investors are calling them, referring to their moneymaking potential. Others see them as nonpolluting, inexhaustible energy sources ripe for development.

Whatever their description, small-scale hydroelectric power plants are generating a lot of interest.

Last month's opening of the Lawrence Hydroelectric Project -- the largest hydro plant to begin operation in New England in half a century -- symbolizes what some observers are calling a gold rush for small hydropower plants. Continued high prices for oil and jumps in new turbine technology are prompting more and more entrepreneurs to throw the switch on hydropower.

"The oil situation is justifying the smaller hydro operation," one industry observer says. "Low-head dams are the most economical arrangement now."

Although the benefits of that hydro boom won't reach the consumer's pocketbook immediately, the potential for reducing foreign oil imports could be significant.

Nowhere is that news so welcome as in New England, a region heavily dependent on oil but blessed with many rivers. Already equipped with nearly 10,000 dams remaining from New England's 19th-century textile industry, the region's rivers are just waiting for hydro development.

In Massachusetts alone, more than 100 dams have been deemed feasible for restoration and development by the New England River Basins Commission. Some 1. 2 million barrels of oil could be saved annually if these sites were put into production.

Beyond the continued high cost of oil, incentives for small-scale hydro development include a three-year-old federal law now taking effect requiring public utilities to purchase electricity from private generators.

Another carrot for hydro investors is further tax credits for developing existing dams. In addition, streamlining the licensing process has helped cut construction time enormously. The Federal Energy Regulatory Commission has sliced a normal two-year waiting period in half.

In the wake of these improvements, the commission anticipates nearly a fourfold increase in hydropower plant applications this year over last. Of the 2,000 projects coming under review in 1981, 30 to 50 percent are for "low head" dams -- small-scale operations that produce 15 megawatts or less.

Low-head dams can generate electricity even in rivers with only moderate flows. Hydropower operations have traditionally demanded tremendous rivers and giant dams -- like the 726-foot Hoover Dam -- to obtain enough pressure for electrical production: now 70-foot dams can be used. Improvements in turbine technology are largely responsible.

A bulb-turbine/generator unit that has long been used successfully in Europe is now revolutionizing the US hydropower industry. Resembling submarines sitting on the riverbed, the turbines produce electricity by channeling water horizontally through their bulbous shapes and against the propellerlike blades.

The Merrimack River project here is one of the first hydroelectric plants in the country to make use of the new turbines. The 133-year-old dam has been outfitted with two of them. After two years of construction, the dam is capable of producing enough electricity to power 17,000 homes.

In addition to the rash of developers now clambering over the New England hillsides in their haste to establish hydro claims, the two partners in the Lawrence project -- EG&G, of Wellesley, Mass., and the Salem-based Essex Company -- have ambitious plans for further hydro development in the region. Dams in Penacook, N.H., and Boltonville, Vt., are undergoing renovation this month and should be operational by late 1982.