Wave energy pt 2: the wild world of wave energy converters

Posted by Deanna on November 4, 2022
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Last time I looked at the history of wave energy and what lessons we can draw from past cycles that could be relevant to today’s climatetech challenges.

This week I wanted to create the actual wave energy market map, in part to get a better sense of the variety of wave energy converters (WEC) that are being developed today and in part to better know and appreciate all of the companies that are working in such a difficult but rewarding space.

Though there have been hundreds of WEC designs proposed in the last few decades (130+ are included in The Liquid Grid’s database and 94 in Net Zero Insights' database), only a small fraction of those are still being developed today. I found 25 that are actively on the path towards commercialization (loosely defined to be: 1- not just a project by an academic institution and 2- having at least one announced milestone in the last year). Those 25 land in six different WEC categories that I could identify.

Included in this map:

  • Point adsorbers (or absorbers in some literature) are WECs that float at the surface like a buoy and can be attached to the seabed. They usually, but not always, can capture wave movement from multiple angles. Many translate the movement to vertical pumps on the seabed. Companies creating point adsorber devices include Arrecife, CorPower Ocean, NoviOcean, OPT, Oscilla Power, Resen Waves, Slow Mill, and Waves4Power
  • Related, but not quite the same, are rotating mass WECs. Rotating mass WECs also float at the surface but use an internal rotating weigh to generate electricity. Companies with rotating mass WECs include Seaturns and Wello
  • Submerged pressure differential devices are under the surface and use pressure fluctuations from the overhead waves to generate electricity. Like point adsorbers, they can be fixed to the seabed. Companies with submerged pressure differential WECs are AWS Ocean Energy, Bombora, Calwave, and Carnegie Clean Energy
  • Terminators are a broad set of WECs that specifically orient perpendicular to the direction of the waves (in a “come at me” kind of way) and in doing so, terminate the waves. They are often fixed to a point like the seabed, shore, or an offshore platform. Terminators are very loosely defined and can include other oft-mentioned WEC categories like oscillating wave surge or oscillating water column. For the purposes of this landscape, I’ve separated out oscillating water column but not oscillating wave surge due to design similarities between the oscillating wave surge and other terminator devices shown. Companies that have terminator WECs include Atargis, Eco Wave, Marine Power Systems, and AW-Energy
  • Oscillating water column devices are a class of terminators that uses the wave to raise and lower water levels within a column, which then forces air to go in and out of a turbine. Companies creating oscillating water column devices include OceanEnergy and Wave Swell
  • Attenuators are WECs with segmented parts oriented along the direction of the wave. The relative movement of the segmented parts generate electricity. Attenuator companies include Centipod, C-Power, Mocean Energy, Sea Wave Energy, and Wavepiston

A few observations on this set:

  • As expected, WEC designs are all over the place. The designs can be very different from one another, a factor of the many variables that you have to optimize for in wave energy (efficiency, resiliency, simplicity, maintenance costs, biofouling / corrosion risk, etc.). There are different angles targeted (against the wave, with the wave, pitch, roll, yaw, etc.), different depths operated, different mooring systems, and different turbines used. Even point adsorbers, the category which seems to have the most uniformity, are divided between seabed-fixed vs. free-floating designs.
  • The heterogeneity makes it difficult to understand the value prop of each design. We often talk in the startup world about the need to highlight company differentiation…characteristics that make your company’s technology unique relative to your competitors. The problem with the wave energy space is that it’s too differentiated. The lack of standardization makes it hard to understand exactly what is critical differentiation and what is superfluous differentiation. In a population where everyone is super unique and different, no one can really stand out. For an investor that is not knowledgeable around wave, the many degrees of freedom around the design can be intimidating and discourage investment.
  • Because of the wide variety in WEC design, metrics matter. It’s difficult to observe from the get-go how different WECs stack up against each other just based on design. But if the companies are upfront in publishing target metrics – LCOE, capital cost, maintenance costs, operating parameters, scalability — that can allow for easier benchmarking between companies, which can address the degrees of freedom problem for an investor in this space. It can also allow for easier pro/con discussions, which can help solidify which technologies are fit for which environments/situations.

    Much of this benchmarking effort is underway in other climatetech sectors (carbon intensity and $/kg in hydrogen, LCOS in storage, tons avoided in carbon removal, etc.) but in wave, at least to an outsider looking in, there hasn't been as much of a concerted effort. In being more transparent around metrics, I believe the wave energy industry as a whole can invite more investment.

It's also worth noting that I made some purposeful exclusions in this landscape.

  1. I excluded businesses that combined their WEC design with a specific use case. Ocean Oasis and Oneka Water are using wave energy for desalination, E-Wave is developing WEC systems for aquaculture, and Ocean Motion is developing its WEC for ocean observation buoys. These are worth noting but because of their focused markets, I didn’t think they should be compared to companies harvesting wave energy for general electricity.
  2. A portion of ocean energy to be harvested includes non-wave kinetic energy from currents and tides. Companies like Current Power Energy Solutions are targeting ocean currents while companies like Nova Innovation are targeting tides. These are worth their own deep dive at some point.

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