Wave Energy – Exploring Renewable Energy Technology

By Vernon Trollinger, October 12, 2017, Energy Efficiency, Green, News

Welcome to Exploring Renewable Energy Technology from Bounce Energy! Because the ERCOT portion of Texas can be thought of as a “walled garden,” renewable energy sources in Texas now make up a significant portion of the energy supply mix. It’s also a dynamic technology with new innovations, discoveries, and issues arising every week. Each month, we will examine the latest news in the industry to better understand what (if any) changes might come to the Texas energy supply.

Wave Energy - Exploring Renewable Energy Technology | Bounce Energy Blog

Is Wave Energy Just a Wash?

While wave-power or hydrokinetic energy for power generation has long been validated by Texas A&M researchers, actual development and deployment of these systems has dwindled, lagging far behind solar and wind projects. In 2011, the Federal Energy Regulatory Commission granted 70 wave and inland preliminary permits. As of September, 2017 , only two preliminary tidal project permits (one in Oregon, one in Alaska) have been filed. Only two licenses have been granted to two pilot projects.

All the same, hydrokinetic power offers an amazing capacity, especially when it’s used as part of a distributed energy resource in a microgrid. For off shore hydrokinetic energy alone, the DOE estimates that 60 terawatt-hours/year can be harvested from the Gulf of Mexico. Approximately 85,000 homes can be powered by 1 TWh/year. Unfortunately, hydrokinetic technology is still very young and needs to develop both a track record of success and good publicity.

That’s the reason that for the past decade, there have been conferences and research prizes designed to spur innovation onward. According to one study, DOE spent $50 million on hydrokinetic energy by 2014.

Wave Energy - Exploring Renewable Energy Technology | Bounce Energy Blog

What Are the Different Types of Hydrokinetic Energy Technology?

Basically, when it comes to just oceans, there have been four types of technologies to harvest wave energy:

  • Attenuators —these are long bobbing, snake-like cylinders joined together with connecting arms and designed to flex as the waves come by. The wave action of going up and down moves the connecting arms, which drives on-board generators.
  • Point Absorber —they have floating heads that move up and down as waves go by. The resulting pump action can be used to compress gas or hydraulic fluid.
  • Terminators/Rising Water Column — think of a big pipe. Hold it vertically and put one end in the water and leave the other end open to the sky. As waves come by, the water level inside the pipe rises. Placing a float inside the pipe will make it act like a piston that rise and falls with each wave. This piston can be connected mechanically to turn a generator or be used to move air through a turbine.
  • Overtopping — this is a floating wall that focuses the incoming waves to swamp or overtop a raised central reservoir. Since it is higher than the water surface level, the water flows downward to spin a turbine, and returns to the ocean.

How Does Wave Energy Work?

Submerged water turbines aren’t exactly new technology. Both riverine and marine hydrokinetic (MHK) turbines work by being submerged and anchored to the bottom. Their blades are spun by the movement of currents, such as those in the entrance to sounds, bays, or in rivers. But because water has a much, much higher power density than air, submerged turbines have the capacity to generate far more electricity while using smaller blades.

MHK systems seem to be the preferred technology so far among the departments of Energy and Defense, and researchers in academia. Though there are no MHK farms in US waters, there has been a decade of small projects designed to find the most productive areas in US coastal waters and rivers.

While nobody has floated an off shore or riverine project in Texas, a 2012 report on US riverine hydrokinetic capacity of the Texas Gulf region shows a potential generating capacity of 8.9 terawatt hours/year. While that’s arguably a drop in the bucket of the entire ERCOT grid, hydrokinetic energy offers another resource for communities interested in further diversifying their microgrid.

Still, until the technology and the industry that’s growing up around it matures, it may be a long time until it makes a big splash in Texas.

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