TECH SPOTLIGHT
Engineering a Sea Change in Ocean Wave Energy Harvesting
C-Power autonomous offshore power systems promise to unlock new marine applications through efficient energy delivery and remote, high-bandwidth communications.
The ability to harness ocean wave energy is a rapidly evolving field that marine engineers are refining to provide reliable, cost-effective maritime energy generation and storage while enabling new forms of offshore data and communication services.
Columbia Power Technologies, Inc. (C-Power), a global leader in wave energy systems based in Corvallis, Oregon, is helping to expand the marine economy by providing reliable, cost-effective energy generation and storage, data and communication services for offshore assets. C-Power autonomous offshore power systems (AOPS) capture mechanical wave energy and convert it into usable power for a wide range of oceanic applications such as offshore oil and gas exploration and production, offshore carbon sequestration, oceanographic research, aquaculture and homeland defense.
Harvesting Ocean Energy on the Kilowatt Scale C-Power has evolved its focus as its expertise in the bourgeoning field of oceanic energy harvesting has grown (Figure 1). While other companies pursue large, megawatt systems, C-Power focuses on remote, kilowatt-scale power for offshore data communications networks, initially through a DARPA project called Wave Energy Buoy Systems (WEBS).
Through the WEBS project, C-Power discovered a nascent opportunity in the form of localized power generation for underwater vehicles, subsea operating equipment and open-ocean sensors used to collect environmental data. Previously, power for these applications
Fig. 1
was generated using expensive, cumbersome, non-rechargeable onboard batteries or subsea electric tethers fed from a ship or diesel generator. With the development of AOPS, C-Power opened the door to unimagined new applications by supplying an autonomous, environmentally friendly, ocean-borne power source capable of doubling as a communications conduit.
SeaRAY Enhances Power Efficiency and Data Communication The latest AOPS platform, known as the SeaRAY, is key to the near-term focus of C-Power to produce power systems that generate 10W to 1MW from ocean waves. To achieve its goals at the lower end of the power spectrum, C-Power created a SeaRAY AOPS design with a high power- to-weight ratio using power conversion technology from Vicor Corporation.
The small design footprint enhances mobility and commercial viability, making SeaRAY easier to deliver and set up, saving tens of thousands of dollars in daily operating costs.
The SeaRAY design also makes autonomous, remote data communications possible by transmitting what happens in the ocean to the cloud in real time. Previously, marine data-gathering systems have been limited in the breadth and frequency of data collection. Using cellular networks and satellite communications to pass data in real-time between the cloud and the SeaRAY allows more
Fig. 2
and richer data to be collected and delivered more often (Figure 2).
Harvesting Energy From a Constantly Shifting Power Source The key power design challenge for C-Power was to reconcile complex ocean wave energy properties with the demanding power conversion requirements of the SeaRAY. This included an ultra-wide 30:1 input range, which reflects the unpredictable nature of ocean waves. The Vicor Power Systems design team delivered a system capable of converting power with high efficiency and charging energy storage devices. The unit is also capable of accepting external control signals from the C-Power system to match precise power conversion needs in real time.
The scalable power design of the SeaRAY uses Vicor BCM® fixed-ratio bus converters and PRM™ regulator modules with complex multistage discrete converters to efficiently convert turbulent, unpredictable wave energy and provide controlled power. This enabled C-Power to increase the SeaRAY design’s conversion efficiency from about 50 percent to a range of 85 to 94 percent.
August 2021
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