CAMBRIDGE, Mass.--When it comes to harvesting energy from oceans and rivers, the "sink or swim" approach doesn't really work.

Getting wave and tidal power machines to actually deliver power into the grid requires multiple stages of testing, with each one a step closer toward deploying devices in open waters, according to experts at a marine energy conference here earlier this week.

Dropping these expensive and often bulky machines, be they underwater turbines or buoys, into harsh ocean conditions without a phased approach and long-range game plan is a recipe for disappointment, they said.

"We need adequate infrastructure that lets us cut our teeth before we hit the high seas and high currents," said Robin Wallace, a professor at the Institute of Energy Systems at the University of Edinburgh, one of a cluster of marine energy research centers in the U.K. "It's not haphazard--it's planned, it's a strategy."

In Massachusetts, a consortium is seeking to build a test bed in the waters off of Cape Cod in the channel between the islands of Nantucket and Martha's Vineyard. In a twist from other test facilities, the proposed site, called the National Offshore Renewable Energy Innovation Zone, would not only test ocean energy but also offshore wind.

"Our position is that (offshore wind and ocean power) testing needs to be integrated because you're dealing with the same environmental and transmission issues," John Miller, executive director of the New England Renewable Energy Center at the University of Massachusetts at Dartmouth, which is part of a consortium behind the project.

Now generating electricity for the grid is the Oyster machine from Aquamarine power. The company is working on a second version of the machine that will be larger but have fewer moving parts and be easier to maintain.

In the U.S., commercial developers are doing environmental testing as part of project development. But a shared testing "sandbox" would allow more companies to test different devices, gather environmental impact data, and generally accelerate the commercialization of the technology, Miller said.

"The problem with so many projects is that it's incredibly expensive to test. Seventy percent of the capital cost is regulations. If it's pretested, that will cut the costs," he said.

Members of the university research consortium, which also includes the University of New Hampshire, University of Rhode Island, the Massachusetts Institute of Technology, and the Woods Hole Oceanographic Institute, plan to apply for a grant from the Bureau of Ocean Energy Management, Regulation, and Enforcement to build the test bed.

It would include berths to place tidal and wave energy machines in the ocean and test offshore wind equipment at different depths. The goal is to raise about $30 million for the site and have it operating in three to five years, Miller said.

Swelling interest Getting energy from the movement of tides and waves has the potential to supply a significant portion of the electricity needs for many countries with suitable resources. But because of the cost and complexity of installing these machines--and a great deal of uncertainty around environmental permitting--wave and tidal energy is very much in its infancy.

Unlike wind, where the three-blade windmill has become common, there are several very different technical approaches to hydrokinetic energy, which can be applied to different environments.

One of the oldest technologies, which recently connected to the grid at an ocean site in the Orkney Islands of Scotland, is the Pelamis Wave Energy Converter, which resembles a giant sea snake. It has cylindrical pumps that move up and down with the motion of the waves to generate electricity.

The Oyster, a huge clamshell-shaped device, started operating earlier this year off the coast of Scotland and is producing electricity for the grid at a low rate. The waves move the top flap to pump water to a hydroelectric generator on land to produce electricity.

Other machines, such as Atlantis Resources' turbine now being tested in Scotland, resemble wind turbines with huge propellers that move from changing tides. Ocean Power Technologies is now testing a turbine in the Bay of Fundy in Maine with horizontal helixes that turn with the tides in rivers and oceans.

But while there's no shortage of ideas for converting hydrokinetic energy into electricity, regulatory and financial barriers have kept most on the drawing board or in testing pools.

Any energy developer venturing into this area has to contend with the lack of a track record in ocean power and the difficulty of connecting to the grid. In financial terms, that means more risk, making it difficult to fund projects.

In a recent example, California utility Pacific Gas & Electric on Monday dropped its effort to develop a wave energy project off the coast of Humbolt County because of the cost of getting permits and infrastructure to connect to the grid. Part of the problem is that the wave energy converter buoy it had chosen remains unproven, according to PG&E.

Environmental data needed In the U.S., there are 17 locations now testing tidal and wave power devices, said Frederick Driscoll, a senior engineer at the National Renewable Energy Laboratory, who recently completed a study on testing facilities. He anticipated the earliest commercial facilities to start operating sometime between 2013 and 2015, although some companies are shooting for earlier dates.

Test beds that suit multiple stages of development--from indoor testing tanks to barges in sheltered areas to the open ocean--are what's needed, he said.

"It's a significant technical and logistical barrier to the U.S. industry. In order for us to compete globally or attract global technology, we need comprehensive and affordable testing facilities," he said.

The location (in red dots) of a proposed 5-megawatt tidal energy pilot project, which would gather environmental impact data. The project is being led by the town of Edgartown on the island of Martha&39's Vineyard (on left).

In Europe, there is already an outdoor facility, called the European Marine Energy Centre in Orkney, and two indoor test facilities are being developed that will do a much better job of replicating the unpredictable conditions of the open seas, said Wallace from the University of Edinburgh. The idea is to make these shared facilities in Europe. Countries in Asia, including China and Taiwan, are also moving ahead quickly with ocean power and have a significant testing infrastructure in place already, he added.

One important component of the proposed marine energy testing zone off Massachusetts is an environmental impact study for the area. The town of Edgartown on Martha's Vineyard received a permit from federal authorities to try to develop a site called the Muskeget Channel, which would be part of the proposed National Offshore Renewable Energy Innovation Zone.

As part of the license, project developers will study the environmental impact of several helical turbines in the water, which could affect the flow of sediment and could impact fish, gray seals, and endangered right whales, Stephen Barrett, director of clean energy at Harris Miller Miller & Hanson.

The goal is to have a 5-megawatt pilot project deployed in 2013 at the site, which would include an underwater cable to Martha's Vineyard. The site itself has the potential for 20 megawatts.

NREL's Driscoll said shared infrastructure to test different marine energy technologies offers several advantages. "If we had [more testing] facilities in place today, we'd have devices in the water," he said.