Georgia Institute of Technology / DOE

A map generated by Georgia Tech's tidal energy resource database shows mean current speed of tidal streams.

Next-generation technologies that harvest electricity from ocean waves and tides sloshing along the U.S. coasts could provide about 9 percent of the nation's demand by 2030, according to a pair of recent studies.

The findings, which include maps of these ocean energy resources, should help guide companies looking to develop them.

"We have believed for a long time that the resource was significant and these assessments add a tremendous level of confidence to what that potential is," Mike Reed, water power team lead with the U.S. Department of Energy's Wind and Water Program told me Monday. 

Today, about 6 percent of the nation's electricity comes from traditional hydropower projects, such as the Grand Coulee Dam, that direct the flow of the river through turbines to generate power.

Since such dams plug up rivers and make it difficult for migrating fish species such as salmon to reach their spawning grounds, they have lost favor in recent years. 

Looking forward, energy developers see promise in technologies that capture the energy in waves and tides off the coasts. 

Designs to do this range from buoys that harness the up-and-down motion of passing waves to turbines on the ocean floor that are spun by the ebb and flow of the tides.

The studies released earlier this month from the U.S. Department of Energy could help nudge along the development and deployment of these technologies by showing the resource is there to be captured.

Motion of the ocean
The U.S. uses about 4,000 terawatt hours of electricity per year. The maximum theoretical electric generation that could be produced from waves and tides is approximately 1,420 terawatt hours per year, the assessments found.

"We are never suggesting that all of that would be captured," Hoyt Battey, team lead for water power market acceleration and deployment with the DOE Wind and Water Program, told me. 

But based on the resource assessments and current understanding of what it will take to scale up and deploy the technology, wave and tidal power could be upwards of 9 percent by 2030.

The DOE has set a goal that water power, including traditional hydroelectricity, total 15 percent of the nation's supply by 2030.

To measure the wave resource, the DOE worked with the Electric Power Research Institute and Virginia Tech to develop a model that accurately predicted past wave regimes and used it to predict future wave climate.

Those predictions are converted into wave power densities. As surfers know, waves from one day to the next are not the same, but they know what beaches tend to have the best waves when conditions are right, Reed noted.

Like surfers trying to figure out where and when to vacation, utility owners and operators can use the new resource data to figure out where the best reliable waves are to put their converters.

This knowledge, combined with reliable forecasts out several days on wave heights, will allow utilities to balance their loads with other sources such as a natural gas fired power plant.

"Wave energy is predictable and forecastable," he said. "If you are a utility operator or utility owner, that predictability adds value."

Tides are even more predictable, noted Battey. "You know down to the second years ahead of time what the tidal regime will be," he said.

The tidal resource maps were created by researchers at Georgia Tech and are available online.

Realizing the potential
Resource assessments such as these, as well as others mapping potential geothermal, solar and wind resources, can nudge development of green energy technologies.

But a key word in such assessments is "potential." As long as generating electricity from coal, oil, and natural gas remains cheap and politically salable, wave and tidal resources will struggle to compete.

Reed takes the long view. Although wave and tidal energy projects today are expensive, he said, their costs should fall as the technology is improved and scaled up over the next few decades.

"A good comparison would be to go back 15 to 20 years in the wind and solar industry and see how their costs have dramatically come down," he said.

While wind and solar still struggle to compete with traditional sources today, the falling prices of the technologies and abundance of the resources are beginning to make them attractive.

Given the size of the wave and tidal resource identified, Reed said there's plenty of room for wave and tidal energy developers to get their feet wet and begin to drive down costs.

More on wave and tidal energy:

• $28 billion in wave energy projects proposed
• IBM sees energy, money in motion of the ocean
• Here's an idea: Floating webs that capture sun, wave power
• Oregon coast could be wave energy hub
• Maine offers testbed for power from tides