Future Forward Full Interview: Harnessing Ocean Waves to Add Another Piece to the Renewable Energy Equation
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Christopher Ridgewell is the CEO at AW-Energy, a Finnish company developing the patented WaveRoller concept and product design to utilize ocean wave energy.
V1 Media: Can you describe your education and career before AW-Energy?
Ridgewell: I studied Naval Architecture and Shipbuilding at the University of Newcastle upon Tyne in the UK, and I’ve been working in the marine industry for almost 30 years since my first job as a summer trainee with a shipowner in 1990. I left the UK in 1992 and have spent the bulk of my career working with a variety of marine technologies in Europe and Asia. It’s been quite diverse and mostly with the implementation of new technologies, for example LNG and passenger ship construction in Europe and Japan, new LNG fueled ships, new ship design tools, first FLNG, and now, since 2014, the commercial implementation of WaveRoller technology.
Wave energy has always been the holy grail of naval architects. As I explored WaveRoller technology, I was hooked; I could really see some great benefits there.
V1 Media: Can you describe your current position and role at AW-Energy? How you became involved with them as well as what the company does overall?
Ridgewell: I started in this company in the beginning of 2014, and I was taken on as chief technology officer, responsible for the technology developments. Just over a year ago, I took the role of CEO. Overall, we design WaveRoller technology for extracting energy from ocean waves. It’s basically a panel that’s fixed to a seabed in the water depth between 10 to 15 meters.
It’s anywhere between 400 meters and a kilometer offshore, and it extracts what’s called “the surge,” the wave-surge phenomenon. Deep at sea, the wind blows on the surface which generates ocean waves, which is a circular motion of the water particles underwater. So when the wind blows over the ocean, maybe for a thousand kilometers, you can have quite a large wave that you see on the surface. You see the wave, say five meters high and a couple of hundred meters long on the surface, but what people often don’t appreciate is that the wave extends deep underwater–the circular motion can extend deeper than 100 meters. As it approaches the shoreline, shoaling takes place and the wave period decreases, so the space between the waves decreases and the wave speeds up. The circular motion becomes more backwards and forwards (or elliptical), and we extract energy from that.
Our panel is fixed to the seabed, and it sways backwards and forwards with the surge phenomenon. And it’s a very efficient form of extracting energy, because you’re trapping the entire water column and extracting energy from this very large volume of water that’s moving backwards and forwards, and the panel actually doesn’t move through the water, it just moves with the water: the surge pulls it backwards and forwards.
V1 Media: How does the energy get transferred from surge to electricity?
Ridgewell: We take this backwards and forwards motion, this rotation, and we turn it into linear motion and then the linear force pumps the hydraulics. One of the main challenges in wave energy is that the forces are very, very high, but the speed is very low.
If you compare it to other types of technology, say a petrol engine in a car, where the torque is quite low, but the speed is quite high. In our technology, we have the opposite issue: wave induced torque is very high, but the speed is very low. So to extract energy from that, we use hydraulic systems. The panel itself can attract up to two megawatts of power. That’s the power going into our power take off system.
Every 10-15 seconds, we have this pulse, this big pulse of power coming in. We capture, store and then we deliver smooth power to the grid. This means we can also optimize the counter torque on the panel to get optimal energy out from the wave. Then we can store that and then deliver energy to the grid.
This onboard storage means that we can do things like follow the grid frequency and support the grid frequency. And that’s sort of the challenge with wave energy: high torque, low speed, pulsating power and then the requirement to follow the grid code – that’s the thing we’ve been able to crack with our technology.
V1 Media: How does the system transfer wave energy to electric energy?
Ridgewell: We convert this rotation into linear motion that then pumps hydraulics. We have hydraulic pistons that turn this linear motion into hydraulic pressure. We store this pressure and then feed it into hydraulic motors that rotate generators. And then we have electrical generators that are rotated by the hydraulic flow. Because we’re storing and smoothing the power, we can keep this rotation continuous so we’re constantly delivering power to the grid in a smooth fashion.
Then we have a shore connection cable that goes out to the land. And on the shoreline, we have a substation. Because we’re quite close to the shoreline all the critical electrical components are on the land. That’s one of the advantages of our technology: we’re close to the shore, because we’re in the 10 to 15 meter water depth–up to a kilometer from the shoreline. We can keep a lot of the electrical components onshore in a substation, which means the maintenance guys can just go up to the substation, do their maintenance without having to go offshore.
V1 Media: You recently received a manufacturing certification from Lloyd’s Register. Could you explain why that’s important and what went into achieving that?
Ridgewell: One of the key cost drivers in any renewable project is the cost to finance. If you look at the recent drops in the levelized cost of energy from offshore wind, that cost reduction has been due to financing costs. The higher the risk, the higher the financing costs. If a financier can place that risk with an insurance company, you don’t carry the risk; the insurance company carries the risk. If you stop producing electricity, how do you pay back your loan that you’ve taken on the project? This is where the insurance is very important to get cost effective finance.
To reduce the cost of that insurance, insurers would like to have a third party check to make sure the technology is reliable: it’s going to continue producing, it’s not going to fall apart on the seabed, it’s not going to cause a pollution hazard, these sorts of things.
So the third-party certification is essential for that, and it’s taken us a long time. WaveRoller is new technology, and there’s no existing code for that. So we had to do quite a lot of work with the certification provider to help them validate the technology. The project started in 2014 with them doing the initial risk assessments for the technology.
For the new technology, we built and deployed a unit in Portugal back in 2012 to 2014. We had a device in the ocean there. We instrumented the device with strain gauges so we could validate, for the certifier, our numerical model used in the design. So that was one part of the certification project: to deploy and test a device in the sea.
Another stream of work was to build a full-scale test facility in Finland. It was a two-megawatt grid connected facility we were using to test reliability, the automation system, and make sure the system could run by itself in big storm conditions. This was a multimillion Euro investment from our side. These were two of the main work streams needed to be done before receiving the technology qualification certificate.
In 2016 the certifier said “yes, the technology is now qualified, and you can now go ahead and design a real project.” And then we went into the project design phase, where we designed the project against the rest of the codes and standards and also using the technology qualification work we’ve done. We received the design certificate back in 2017, and then we went into the manufacturing phase. We had to build the device in accordance with our drawings and to the satisfaction of the surveyors, so they could see its fit for purpose and that we’re using the right manufacturing process.
Our project has been undertaken in several places in the world. So it’s been quite a challenge for a small company to manage that, but we’ve managed to build the technology to the satisfaction of Lloyd’s Register, and they issued the manufacturing certificate, which will reduce the insurance costs, the financing costs. So by reducing the financing costs, the levelized cost of energy reduces further, and it becomes more bankable for the end user. They can see that the technology is going to work; it’s going to produce energy as we say it is, and the insurance costs are reduced.
V1 Media: As the new technology evolves and upgrades, will you need to go through that process again; or because you’ve done it once, is it a shorter and simpler process?
Ridgewell: It’s shorter and simpler after doing it once. We’ve validated our numerical models using sea trials, and that validation will remain valid; the technology qualification is valid. For changes in the design, it’s not a big issue. It’s not as big as technology qualification. So every time we do a project, if we want to get certification from Lloyd’s Register, then we would need to go through a review of the design change and the another manufacturing review.
V1 Media: Could you describe an example project?
Ridgewell: Portugal is good example. We use a refloatable concrete structure that’s manufactured locally. And then we have a panel, the part that moves backwards and forwards in the waves, that’s been designed to be manufactured in any shipyard. So it can be made and manufactured in Portugal. In this case, we manufactured it in Finland, but it could just as easily be manufactured in Portugal. And then we have the power takeoff units as well; steel structures that can be manufactured locally. So a large portion of the capital expenditure is for local manufacturing in countries, wherever that may be, so it will generate local jobs.
So if we would do a project in California, more than half of the capital costs would go into local manufacturing, local job creation, which makes us kind of unique compared to other technologies. If you compare to solar, a lot of the solar panel manufacturing is abroad. But we want to manufacture more than half of the components locally, and as the size of the projects increases, that proportion increases. And we bring all those components to the assembly site, and we assemble them and then tow them to the site and deploy into the seabed. And then they basically start producing electricity as soon as they hit the seabed and start generating to the grid. It’s a simple deployment.
We’ve deployed devices in Scotland, Ecuador and Portugal. In Portugal, we built a larger 300 kilowatt unit that we first deployed in 2012 as a test. What we’re building now is the commercial certified version of that.
The testing campaign back in 2012 to 2014 was also used to validate the power production numerical model. DNVGL took the wave data, the data of the power produced to the grid and our estimates based on out numerical model. The results of this exercise showed that the device produced as we had expected, so we’re quite confident about the electricity production.
V1 Media: What are the advantages of wave-surge energy over other forms of renewable sources?
Ridgewell: A major advantage is being discussed in California, which has an objective to go to 100 percent renewable energy. The big challenge in California is that it’s windy and sunny in the summertime; the hot days in the desert creates the wind. But in the winter, there is a big dropoff in this power production; for the 80 percent renewable scenario, the gap in December is about five terawatt hours, so it’s a huge gap in the resource. Some of the debate has been to store energy in the summer and deliver it to the grid in the winter. If you look at the amount of rare materials you would need for that storage, the numbers are mind-boggling. It would require huge quantities of lithium to store that amount of energy.
So if you take five terrawatts in December, that’s the same amount of wave energy coming into 100 miles of coastline. So you can fill that gap between the summer and winter with wave energy. Of course, you still need storage. Storage provides flexibility, so storage would be good for within the day, rather than within the seasons. So wave energy has a big role to really deliver renewable energy in all seasons in California and other regions.
We see that wave energy is also highly predictable compared to wind and solar. There’s been a lot of work in offshore marine engineering to predict wave energy based on weather simulations, so it’s possible to predict wave energy about a week ahead in the major oceans, and about two weeks in the tropical oceans. So it’s a very predictable. It’s possible to sell next week’s renewable energy as opposed to solar, where you just don’t know when the clouds are coming.
So advantages include predictability and the seasonal advantage that compliments other renewables. And I’d say the third point worth mentioning is the value deflation in existing renewables. So as more solar comes onto the grid, when it’s sunny, solar competes with itself. Each new solar panel you put in it will compete with the others. And you see the same in wind as well. Value deflation really starts kicking in; I’ve read about 20 percent for solar, and maybe wind about 30 percent.
Waves are generated by the winds, but when the wind stops, the waves still come into the beach. The entire ocean is generating wave energy; you can think of the ocean as a giant battery, and we plug into it with WaveRoller. As value deflation of existing renewables starts to kick in, it may be more difficult to reach these renewable energy targets, and the return on investment is reduced. So that’s another benefit of wave energy: it can be produced to the grid at a different time compared to the current forms of renewable energy.
V1 Media: What might be considered a disadvantage?
Ridgewell: I think the biggest challenge is being a newcomer to the market. You see the costs of wave energy now are high compared to wind and solar; it’s the same as with wind and solar when they were early technologies. The costs were high, but they both had a lot of support. In wind energy, there was a lot of support from, for example, Germany that supported the technology development. I think the same thing is true for wave energy, although I reckon we’re already starting with a lower levelized cost of energy than wind energy in its early days. The challenge is to overcome this hurdle and move to larger projects to really get the costs down, and the costs will come down.
Like all new technologies, the costs come down very quickly in the beginning as the size of projects increase, and then learning increases, and then all sorts of new ideas come to bear. All these costs start to reduce, so I’m very confident about the cost side. There is definitely a very strong case for wave energy in the future.
V1 Media: So what happens during a major storm event? Does the technology continue on or does it need to be paused?
Ridgewell: In a storm condition, we continue to operate. One of the benefits of being submerged is we’re nicely tucked away underwater, and we’re safe from the air/water interface. When you’re on the surface, you have the wind, then you’ve got the breaking waves slamming into you, and it’s very violent on the surface. But when you’re subsea, you’re protected to some extent. So you still have those waves coming in from the deep ocean, and the wave period is still pretty much the same. The storm is local; it’s local winds and waves at the surface. So we still continue to operate. Another thing we often see in storm conditions is an increase in the water level, so the storm system pushes water ahead of it, and the sea level rises. So the air/water interface is even further away from the technology, from the device. So in these conditions, we just continue to operate.
V1 Media: Are certain coastal areas better or worse suited to the technology?
Ridgewell: The technology’s suited for large oceans, so it’s not very good here in the Gulf of Finland: the sea is far too small, the wave period is not long enough. We need a large ocean where the wave period picks up, and the entire water column is activated. So the California coast is ideal, and the Chile coast is ideal, and the Portuguese coast and Scottish coast, where we’re facing a large ocean.
V1 Media: How can wave-surge technology affect the overall energy system? How much energy can it produce compared to other technologies, whether renewable or traditional?
Ridgewell: The opportunity is rather large. In California, WaveRoller technology could fill the gap between summer and winter due to the drop in the wind and solar resource. So that’s a very large contribution. If you look at the entire United States, then it’s a different story. I’d say we need different wave energy technologies to come to bear as well. So we’re in the coastal area; other technologies under development are in the deeper sea further offshore. So I’d say wave energy technology can make a very big contribution to the energy system in providing stability, in providing predictability, in providing energy when it’s cloudy, when it’s nighttime, when wind stops blowing, those sorts of things. I wouldn’t imagine wave energy technology supplying the entire grid.
It’s a technology that complements other renewable energy sources. We need different tools for different places, and this is one technology and one tool that can be applied to create increased grid stability, and then other types of renewables will be deployed as well.
For example, in Chile, the amount of wave energy coming into the coastline is far greater than the electricity demand in the country. On the other hand, we looked at California, and the wave energy can make a very big contribution to the energy demand in the state. It depends on the country. In South Africa, we can make a very large contribution, and the wave energy there was more than the demand. In Australia, it’s definitely more than the demand. So it’s case by case and depends on the country, the wave resource and the electricity consumption.
V1 Media: Could you share with engineers some advice you’ve learned from your experiences?
Ridgewell: Let’s compare the design development to a battle. When we think about the components of the technology, we can think of them as sort of divisions in the army. You need to keep the whole front moving forward. You can’t just optimize one area. There are so many different technologies and components.
It’s really important to try and keep everything moving along at the same speed, during concept design all the way through to detailed design and think of it as an entire system. And think of it in terms of the customer. What does the customer need to do, from their perspective, to deploy a wave energy farm, to maintain it, to finance it? Look at the challenges from the customer point of view and think of it as a holistic whole rather than individual components. I think that has helped us a lot. That holistic thinking of the entire product solution rather than individual components has helped us find the overall optimal solution rather than just the optimal for one component.