Tidal energy is a renewable energy alternative that is not new, but it is not as widespread as like wind or solar energy because it is more difficult to achieve efficiency and usually requires large structures. So, from time to time, ideas such as SeaRAY arise, a floating platform to harness the energy of ocean waves.
The National Renewable Energy Laboratory (NREL) has been working with the U.S.-based marine energy company C-Power, to build a wave energy converter that can power what is, effectively, an underwater version of an electric vehicle charging station. It’s a station where undersea drones could stop to recharge.
According to the developers, the autonomous, wave-powered, renewable energy device – called the SeaRAY autonomous offshore power system (AOPS) – could power offshore work and help protect our oceans and climate, too.
The SeaRAY AOPS can be smaller or larger to meet specific needs, generating between 100 watts and 20 kilowatts – enough energy to power anything from a seafloor data-gathering system to a medium-sized subsea vehicle or surface vessel. On the ocean’s surface, a wave energy converter captures and transforms wave motion into electricity, which is then stored on the SeaRAY and in a seafloor battery. The SeaRAY AOPS not only makes and stores clean, carbon-free energy but also shares data with the offshore vehicles it powers.
Designed by C-Power, the SeaRAY AOPS could provide clean energy for offshore activities, including aquaculture (like offshore fish farms), mining, oceanographic research, military missions, methane leak monitoring at underwater oil and gas wells, or even desalination for remote communities and natural disaster recovery.
NREL, in particular, is working on the novel field data collection and control system called Modular Ocean Data Acquisition (MODAQ). The system will continuously collect information about waves, currents, winds, and the performance of the platform itself. The MODAQ system can be the brains of these wave energy devices and allow the team behind SeaRAY to understand if the platform works as intended while rocking with ocean waves. But before MODAQ goes underwater with SeaRAY, the team must protect it from a corrosive and violent ocean.
To make sure the SeaRAY AOPS is ready for a six-month oceanic trial at the U.S. Navy Wave Energy Test Site in Hawaii, NREL researchers are simulating rolling ocean movements at the laboratory’s Flatirons Campus in Colorado.
“NREL has a critical role in this project,” said Reenst Lesemann, C-Power’s chief executive officer. “They’re not only helping provide the brains of the AOPS but also helping with testing and debugging the system before we get into the water.“
In Hawaii, project partners, including Saab, a world leader in electric underwater robotics, the National Oceanic and Atmospheric Administration (NOAA), and BioSonics, will pair the SeaRAY AOPS with their electronics, which collects data on methane and carbon levels, fish activity, and more. Normally, autonomous underwater vehicles like Saab’s need power from a topside ship that emits about 7,000 cars’ worth of carbon dioxide per year.
“With Saab,” Lesemann said, “we’re looking to show that you can avoid that carbon dioxide production and, at the same time, reduce costs and operational complexity while enabling autonomous operations that are not possible today.”
The SeaRAY autonomous offshore power system has about 70 sensors that collect massive amounts of data. SeaRAY’s wave energy converter uses two floats, one on each side, which rolls with the ocean waves and connects to a power take-off system – a mechanical machine that transforms that motion into energy. This system then runs a generator that connects to the seabed batteries, a storage system that NREL will also test before the sea trial.
This fall, the SeaRAY device is expected to be packed into a standard shipping container and sent to Hawaii. Once the open field test is complete, the MODAQ system will provide the C-Power team with data to further improve the SeaRAY device and make it even smaller, lighter, more efficient, and more adaptable for a wider range of applications.