Hydropower took a huge step forward yesterday, when a 400-ton test turbine was lowered to the floor of the Bay of Fundy in Nova Scotia. By mid-afternoon, its blades were rotating with the tides, collecting data and producing power.

Hydropower is getting a lot of attention these days.

For one thing, the U.S. Department of Energy recently announced that seven projects would be getting $30.6 million in recovery act funding.

In a podcast earlier this year, Renewable Energy World’s Stephen Lacey said hydro in the U.S. was poised for another period of major growth. “With states recognizing hydro in renewable portfolio standards, companies getting access to stimulus funds and a range of new players getting into the industry, the environment is looking good,” he said.

Hydropower involves converting the motion of water into electricity. The technology can use the flow of rivers, the action of tides or even the energy of ocean waves. Dozens of projects are either in the planning stages or the works for many rivers.

Just across our border, Nova Scotia has been a leader in the technology. A quarter century ago, North America’s first — and, so far, only — modern tidal plant was built in Annapolis Royal. It sits astride the Annapolis River, on the southern shore of the Bay of Fundy, which sees the highest tides in the world — 30 feet or more each cycle.

Basically, when the tide is coming in, sluice gates are opened so a head pond can be filled. The gates are closed when the tide begins to fall, and when there’s a differential of about five feet between head pond and the river below the plant, gates open and the flow of water begins to turn a turbine. The plant generates enough electricity in a year to power 4,500 homes.

But the technology is old. Today, scientists have set their sights not on the vertical motion of the Fundy tides, but their horizontal motion. Several companies have been designing a way to install huge turbines on the floor of the bay. Fisheries officials and others have expressed concerns about whether the technology will affect aquatic life.

But yesterday, Nova Scotia Power and its partner, OpenHydro, deployed what they said was the first commercial-scale in-stream tidal turbine in the Bay of Fundy.

It took seven days to get the turbine from Halifax to the deployment site — just off the Minas Basin, on the northern side of the bay.

“Today begins a very important period of testing that we believe will demonstrate that tidal energy can be part of Nova Scotia’s renewable energy future,” said Rob Bennett, president and CEO of Nova Scotia Power.