Helping to fix the climate crisis: The planet’s largest battery – the ocean

By Christopher Ridgewell, CEO, AW-Energy

The WaveRoller® operates in near-shore areas (approximately 0.3-2 km from the shore) at depths of between 8 and 20 metres, converting ocean wave energy to electricity
The WaveRoller® operates in near-shore areas (approximately 0.3-2 km from the shore) at depths of between 8 and 20 metres, converting ocean wave energy to electricity (illustration: AW-Energy)

“When are you engineers going to invent something to fix the climate crisis?” That’s a sentiment that I often hear, and I must admit that it does add some pressure, although it also feels worthwhile to be part of the team, engineers and many other professions, working on solutions. It’s an enormous and complex global challenge, more great teams are joining but the invention of a single game-changing solution is unlikely.

We need a more diverse set of tools in our toolbox to build a comprehensive and workable repair. This is borne out by a recent article featured on the front page of Der Spiegel, lamenting Germany’s failure to reduce carbon emissions from electricity generation, despite efforts to expand solar and wind energy projects. Simply put, the challenges in building out projects requires systemic improvements in all areas, and even then, when the wind stops blowing after a few overcast days, electricity generation falls back on coal. Thus, a more diverse set of technologies are needed that can continue to generate when others tail off. Instead of celebrating the massive reduction in generation costs of wind and solar, achieved in part by government support, we need to double down and quickly deploy new solutions with the same nurturing approach.

Another good example of the challenge to roll out renewables is California. The target is clear: last year Governor Jerry Brown signed into law 100% clean electricity by 2040. That’s just 20 years from now; a very short time, especially considering the time it takes for energy projects to be realised. The big question is how this target can be achieved given the tools in our toolbox. In California wind and solar electricity production peaks in the summer months. The challenge of seasonality was reported last year. If wind and solar equally shared the target of 80% renewables, then the production in the summer months would be 10 times more than the winter months. The shortfall in December would be about 5 TWh. Perhaps it would be possible to build out capacity and storage so that electricity produced in the summer could be stored in cheap batteries and then delivered in the winter, but the scale is enormous. For the 100% renewables, using wind and solar, over 36 TWh of storage would be required to store energy in the summer and deliver it in the winter. To set that in perspective, using existing lithium ion battery technology the demand would far outstrip the current global supply of lithium. So, many believe that in order to deliver the 100% renewables goal in California new battery technology is required. But this ignores the planets largest battery, just adjacent to California, the ocean.

Concentrated energy
California is blessed with a long coastline that has some of the best wave conditions. On average over the year the wave energy flux is about 600 kWh/m/day, higher in the north and lower in the south. In comparison the solar resource in California ranges from 4 to 8 kWh/m2/day. So, as can be seen, wave energy is a very concentrated form of energy. The sun’s rays are absorbed by the ocean creating both a circulation that extends deep below the surface and the weather patterns that create the winds that strike the ocean’s surface creating waves.

The oceans could be imagined as the earth’s largest solar panel. Imagine a strong breeze blowing over 300 miles of ocean. The resulting wave is about 5 metres high, but what’s not easily observed is the water particle motion that extends down to over 100 metres below the surface. In the case of California, the ocean waves are generated over an enormous distance – Japan is over 5,000 miles away. Thus, the oceans both store and transfer vast amounts of energy in the form of waves. When the sun goes down and the wind stops blowing those waves are still barrelling towards the coast – now stored in the earth’s largest battery.

A WaveRoller farm – installed and operating in the nearshore area – easy access to site, protected from extreme conditions and minimised balance of plant infrastructure cost
A WaveRoller farm – installed and operating in the nearshore area – easy access to site, protected from extreme conditions and minimised balance of plant infrastructure cost (illustration: AW-Energy)

Just like solar and wind energy, wave energy is also seasonal. However, this is also one of the great values of wave energy as the seasonality in California is out of phase with both wind and solar. Wave energy peaks in the north to well over 1 MWh/m/day in winter and falls off to one quarter of that in the summer months. To give some scale, the 5 TWh winter shortfall is equivalent to the wave energy heading towards 70 miles of coastline. That’s about the same length as the developed wind resource areas at Mojave and Palm Springs placed end to end.

Renewables toolbox
Unlike California, Germany does not share the coastline of a large ocean. But Europe does and shares a transmission grid. There’s been steady progress in Europe where the ocean energy sector is projected to add 400,000 highly skilled jobs by 2050. Several great teams have been working on different wave energy technologies for many years. The technologies can be characterised as offshore, nearshore and onshore. It’s easy to see scenarios where each of these technologies are deployed at scale. Not competing, but instead playing to their strengths in different parts of the ocean. They may even share project resources, such as subsea cables and grid connections.

I’ve personally been working with a great team for the past 5 years developing WaveRoller technology, which has its origin back in ninety’s. WaveRoller is a nearshore technology, consisting of a panel that is hinged at the seabed and moves back and forth in the ocean swell – the subsea portion of the wave that I described earlier. Smooth, grid compliant electricity is generated from this mechanical motion and transferred about a mile to the shore and then the substation.

WaveRoller is just one tool in the toolbox needed to transition to 100% renewables, but in California it is ready to play a significant role. Most of the WaveRoller device can be manufactured locally as well as operated and maintained locally, thus generating tens of thousands of new highly skilled jobs in a new industry.

Enormous amount of energy
To open the path to project financing our team has focused on insurability. From ocean testing with strain gauges, to bench testing the power take off at full scale, we’ve invested millions in the testing required to reach all the third-party certification milestones needed for project insurance, i.e. the insurance of the power production. This has been a huge achievement by our talented team and now we are ready to rollout WaveRoller projects.

It’s evident that we need more tools to tackle the climate crisis. Tools that can utilise new untapped renewable energy resources. The oceans hold an enormous amount of energy and both Europe and the United States, as well as many other regions, are ideally situated to exploit this domestic resource, in the process creating many new skilled jobs and substantially reducing carbon emissions. We need to start right now and WaveRoller is ready to help our planet plug into wave energy.

Christopher Ridgewell, CEO of AW-Energy
Christopher Ridgewell, CEO of AW-Energy

Christopher Ridgewell joined AW-Energy in 2014 as CTO and was promoted to CEO in 2018. He has almost 30 years of professional experience working with marine technology. Mostly in the safe implementation of new technologies, from LNG Carriers, FLNG and LNG fuelled ships to passenger ships, submersibles and novel 3D design. He left the UK in ’92 and has worked extensively with both technology and business development in across Europe and Asia. He is also a Fellow of the IMarEST.

As a Naval Architect, he has long followed and been fascinated by the development of wave energy technologies and once he became familiar with WaveRoller technology he felt compelled to leap in to the sector. With its major benefit of both a diurnal and seasonal phase difference from wind and solar, he passionately believes that wave energy must be implemented in order to secure the energy transition and WaveRoller can make an important contribution.

WaveRoller technology is core to several wave energy projects around the world. Recent several important milestones have been achieved, such as third-party technology development, design and manufacturing certification, that will enable project insurability and bankability and the global rollout of WaveRoller.

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