Space Zoo Patrol – Marine Energy (Wave Systems)
By Julie Mai, Head of Communications & Public Affairs, CalWave
Background
- What is this technology called?
The generic term is “wave energy converter technology.” Our company, CalWave, calls our version the xWave.
- How does it work?
CalWave’s xWave technology taps into the wave power of the ocean. It takes on the form of a submerged pressure differential wave energy converter. The device is anchored to the seafloor and is capable of operating at a range of different water depths and distances from shore. As waves pass overhead, the water level above the device rises and falls, creating a pressure gradient (change) that causes the device to orbit (move) from its moored position. Generators inside the device use this relative motion and convert it into electricity that is then transported back to shore via a subsea cable. The xWave architecture achieves the highest efficiency by operating fully autonomously and fully submerged, absorbing power from multiple degrees of freedom (3 directions of motion). Unlike many other technologies that extract wave energy at the ocean surface, our device’s refined approach enables several improved operating capabilities: It survives stormy seas and extreme conditions, permits energy capture from multiple degrees of freedom, allows for precise control of structural loads, and
- Who invented it? And when and where?
The xWave technology was invented by CalWave’s founding team out of UC Berkeley in 2014.
Advantages
- What are the environmental advantages?
- Wave power is the world’s largest unused renewable energy resource, capable of satisfying over 30% of US and global electricity demand. The key benefits of wave energy include greater consistency, predictability, and energy density than existing renewables. Wave power is available both day and night and generally peaks in the winter, providing an especially large resource during cold nights when energy demand soars.
- Being underwater, the design causes no visual pollution.
- Established renewable energy technologies, such as solar and wind, have the potential to meet a large portion of the US’ energy demand, but have begun to encounter integration challenges as they’ve scaled up that suggest a need for energy storage, as well as societal challenges such as environmental impact concerns and competing land use. Marine energy also has the potential to contribute significantly to the nation’s energy needs, and—because it is located at sea and can be forecast with greater accuracy—may not have the same challenges.
- The OES-Environmental State of the Science Report for 2020 (the Ocean Energy Systems is part of the International Energy Agency) represents the most comprehensive international collaboration on the effects of marine energy on marine ecosystems. The report suggests that key risk stressors for marine energy deployments such as collision, entanglements, and electromagnetic field concerns may be eliminated with additional monitoring for validation. In over a decade of marine energy deployments globally, there has not been an observed mammal or fish mortality or strike involving marine energy technologies. In more recent assessments, PNNL (Pacific Northwest National Lab) concluded that CalWave’s 10-month wave energy pilot deployment off the research pier at the Scripps Institution of Oceanography (SIO) in La Jolla, CA “would have no adverse effect on local fish or invertebrate species and it is not likely to adversely affect species of marine mammals, turtles, and seabirds that could potentially visit the project area.” Furthermore, PNNL observed “possible artificial reef effects, or creation of habitat, on the device’s anchors and moorings, which could be a positive ecosystem effect.” This assessment of CalWave’s deployment at SIO was an encouraging step for the wave energy industry.
- What are the life cycle financial advantages?
- Winter-peaking resources with seasonal variation such as marine energy will be crucial for achieving high deployment levels of renewable energy. Marine energy would require a fraction of the associated integration costs of other variable resources as it is a predictable resource.
- Our xWave technology is designed to be able to withstand over 20 years of use in open-ocean and has been designed to survive 50-year storm events. With operation and maintenance processes occurring on the surface via hot-swap capabilities (while power is still connected), incurred costs are also predicted to be lower than that of offshore wind.
- Co-location with offshore wind may also provide value in sharing infrastructure and associated costs between technologies.
- What jobs are created? (design, manufacturing, installation)
- Wave energy presents a significant opportunity for high-quality job creation and economic growth. The wave energy industry can create similar numbers of local jobs for fabrication, operations, and maintenance as the offshore wind industry. Estimates project that by 2050 over 300 GW of marine energy capacity will be installed globally, resulting in the creation of 680,000 direct jobs.
Energy Production
- How efficient is this technology? (percentage efficiency)
- The xWave achieves a capacity factor of 40-50% as a stand-alone solution. Studies show that when co-located with offshore wind, the joint capacity factor can be greatly increased.
- How many units are needed for 1 house, 1 school, 1 community?
- CalWave’s core xWave products, the x100 and x800, are rated at 100 and 800 kW respectively. The x800 produces enough electricity to power about 3,000 households.
- What percentage of total energy usage (US, world) does this technology provide today?
- At present, ocean energy accounts for barely 3% of global electricity generation – although a large portion of this represents offshore wind energy.
- What percentage of total energy usage (US, world) could this technology provide?
- Wave energy is capable of satisfying over 30% of US and global electricity demand. In a recent report by the U.S. Department of Energy, the total marine energy technical resource in the United States was found to be 2,300 TWh/yr or the equivalent of roughly 57% of 2019 U.S. electricity generation – enough to power 220 million U.S. homes.
- What geographical areas can this be used in?
- Our technology is scalable to meet the needs of varied end-users, so this means that our xWave will be able to power large coastal cities through utility-scale grids and also more remote coastal cities and islands through local energy grids and microgrids.
Engineering / Mechanical
- How is it manufactured?
- Manufacturing currently takes place in our Oakland facility, however, we plan to manufacture locally within the communities that we serve going forward.
- What maintenance is required?
- A full maintenance cycle is expected to occur every 4-5 years. Annual inspections will take place both remotely and locally. Bio-growth on non-functional surfaces of the xWave device presents no concern and does not reduce performance. Bio-growth on functional surfaces is significantly reduced, as per definition, these surfaces are constantly cleaned via actuation/operation. CalWave has validated the above during our San Diego deployment. Further, all technical operation and maintenance processes occur on the surface via hot-swap capabilities.
Education
- What classes should I take in school to work on this technology?
- Students looking to work directly on this technology would benefit from STEM classes overall. Additionally, courses related to offshore renewable energy, technology development, testing marine energy converters, marine operations, environmental effects, and society & policy would be valuable to pursue.
- The wave energy industry presents many different career opportunities and pathways, not limited to technical roles. Classes in business development, communications, sales, marketing, environmental monitoring, and policy can also prepare students to work in the sector.
At the dock ready for pickup
Deployed at sea
