Wave energy test rolling forward in Hawaii

July 28, 2015 Amy Gahran

Just off the coast of Oahu, Hawaii, last month a wave energy generator began contributing small ripples of electricity to the local utility's grid. In this one-year test of new technology, the U.S. Department of Energy and the University of Hawaii are collaborating to gather data which could help shape the future of wave energy technology.

This test also will help show how well wave energy might help utilities address crucial, growing challenges with maintaining grid stability while relying more heavily on renewables.

The 20 kW wave energy converter from Oregon-based Northwest Energy Innovations, called Azura, doesn't quite produce enough electricity to power even a single home. But it represents a significant technological advancement.

Azura is one of the first devices developed that will demonstrate conversion of ocean energy to electricity by absorbing energy through both up-and-down and back-and-forth wave motions, enabling its converter to generate more electricity than previous such devices.

In addition, the energy-harvesting "float" at the top of Azura can rotate 360 degrees, reducing mechanical stress and helping prevent failures - a problem with earlier technologies.

Azura sits in 30 meters of water in a berth at a U.S. Navy testing facility, where undersea cables and a supportive stakeholder made it easy to site the test. (As with ocean wind power projects, finding a home for wave energy projects can prove complex or controversial.)

Steven Kopf, CEO of Northwest Energy Innovations, said the university's independent validation and analysis of data from this test is a critical step in moving wave energy technology forward.

"Utilities and power project developers won't even consider buying wave power technology unless they can see what an independent third party says it can really do," said Kopf. "So we're consciously running this test in all sorts of conditions, even when wave conditions are suboptimal for power production, just to get a complete picture of performance."

DOE agrees. "This pilot testing is now giving U.S. researchers the opportunity to monitor and evaluate the long-term performance of a grid-connected WEC device in the open ocean," said a spokesperson. "So far, this project has already proven valuable in identifying deployment efficiencies, gathering performance data, and developing operations and maintenance procedures. The learnings from the Azura deployment will accelerate the ultimate technology commercialization."

Northwest Energy Innovations designed Azura using standard components, in order to help keep production costs down - another challenge with earlier technologies.

Cost is one of the most critical issues with wave power. As with all new renewables, the initial cost of wave power is relatively high. According to the Ocean Energy Council, recent experience in the U.K. (which is more advanced in wave power testing and deployment) is about 7.5 cents per kWh at best. The industry goal is to get this down to about 4.5 cents per kwh - comparable with the cost of wind power, although still much higher than the cost of fossil-fuel generation.

However, wave power offers some notable potential advantages to compensate for that cost.

In addition to helping states meet renewable energy targets, proximity to demand often reduces the cost and complexity of power transmission - and about 50% of the U.S. population live within 50 miles of a coastline. A 2011 Electric Power Research Institute report found that available wave energy resources offer the potential to meet about one-third of current U.S. electricity demand.

Addressing environmental concerns, laying undersea cables and gaining stakeholder cooperation does take work.

One reason utilities and power network operators might be especially interested in wave power is that it tends to be far more predictable than wind or solar power. According to the DOE, this advantage might help compensate for the complications associated with deploying wave power, which include "locating an undersea cable for bringing the power to shore, while avoiding conflicts with shipping lanes, fishing grounds, military exercises or any of the myriad other ways we use our bustling coastal waters."

Still, predictability saves money. "Generally you can see four days out, with a high level of certainty, what the wave conditions will be," Knopf observed. "This allows power planners to know what they can count on from wave power, which makes it easier to control overall costs for electricity."

Hawaii may prove to be a promising initial U.S. market for wave energy. In June, Hawaii passed legislation requiring an even more aggressive increase in renewable energy production: 30% by the end of 2020, 40% by 2030, and 70% by 2040.

The state also has, by far, the highest cost for electricity: 34 cents per kWh, according the U.S. Energy Information Administration. Also, Hawaii is reaching the limit of the amount of solar energy its grids can handle.

Kopf acknowledged that cultivating investors for wave energy is challenging. "Early technologies didn't pan out, and a lot of investors got burned," he said. "But we've been quietly chipping away at this problem, and gradually investors are starting to get re-interested in it, now that they see the technology didn't completely bomb."

Last October, DOE awarded Northwest Energy $5 million to apply the lessons learned from the Azura test in Oahu to develop a full-scale unit - which Kopf says will provide up to 1 MW of power. Also, DOE is holding a Wave Energy Prize contest, to spur development of WECs with double the energy-capture potential of current technologies.

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