Tidal Power Platform Designs Driven by Economics

Jason Deign of Tidal Today spoke to Niels A Lange, manager of the Schottel Josef Becker Research Centre in the lead-up to The International Tidal Energy Summit (24-26 November 2014, Victoria Park Plaza Hotel, London, UK).

In the context of the huge forces at sea, the severe tides and the ‘tidal window,’ what is critical when developing marine technology?

My general answer would be that coping with these forces starts with the design concepts. If the basic setup of your device already allows for keeping forces on individual structural components low, by its shape or by its appearance or by its compliance, then this is a very important first step to keep the forces as small as they can be. 

This is one of the major advantages of tidal energy compared to wave energy. In wave energy you need to go where the forces are biggest. Here you can use a clever design to minimize the forces. We follow a platform approach. Our platform has a design which is less affected by waves than other floating platforms. That’s what I mean by basic design, or design principles. The shape or the basic layout of the device determines the forces that you need to cope with.

On the individual turbine, of course, the forces are rather similar, because you are having to harvest the flow. In that sense you need a design certification that is as good as you can get. The crucial thing is to understand the environment, and then you can design for it.

Survivability, reliability and increased performance are central to the sustainable development of tidal power. What are you going to do to make a difference in these areas and how will it affect the cost of energy?

In terms of reliability, we often talk about redundancy. And redundancy in principle increases the cost of the device and therefore the cost of energy. However, we are following a multi-turbine approach, so if one or two turbines fail we don’t really care because that’s the redundancy we have. The individual device is pretty cost effective. Pretty cheap, you can even say.

If one or two of 36 devices fail, then the overall availability or the overall production of the plant is still high. That’s again a matter of design principles. Talking about cost of energy, the resource is for free. The flow is there. The question really is to minimize opex and capex in order to harvest this energy, which is for free, for the lowest possible price. Your design needs to be driven by the economics.

There are things you can do in terms of engineering and materials, making everything more robust and heavier. That is something you can do to make things more reliable. But it might be over the top compared to a more clever approach.

Realistically, what timeframe do you work to in order to get through the research, development and testing phases and reach the point where your technology can start making an active contribution to the tidal industry?

My view on the entire industry is that most other technologies apart from our own rely on the fact that they need to scale up in terms of having multi-megawatt arrays before they can become commercial. In terms of the infrastructure cost that probably is true in any case, because putting in one or five sea cables is probably the same cost, basically. In that sense, up-scaling is required.

In terms of the device cost, for other developers the same thing applies. They will hopefully come down with their costs if they build hundreds of units. However, we claim that our first demonstrator project in Bay of Fundy will already pay back its cost. That’s based on the great feed-in tariff which we have in Nova Scotia. However, that’s the same feed-in tariff for all developers there. Our project there will be profitable. It will be deployed in two years’ time.

What will you take responsibility for in terms of bringing technology to market and reducing the cost and risk associated with innovation and subsystem development?

Our first demonstrator project claims to be profitable on its own. Apart from the fact that we are convinced our technology is cost effective anyway, it’s also driven by the fact that a company of our size, Schottel, with €300 million turnover, is not capable of spending a fortune in this technology. However, compared to our company size we still have a very high commitment to this demonstrator unit because we pay for it on our own before it starts paying back with the feed-in of energy. So for our project that’s a pretty high commitment.

Unlike what we are used to with our core product, ship propulsion, the future customers, project developers and especially utilities, expect the developers to take this pretty far down the road before anyone thinks about buying this as a customer. Any developer that thinks about utility-scale projects needs to take a high risk.

Delivering reliable and cost-effective technologies will be paramount to the ultimate commercial success of the tidal industry. What is the single biggest challenge in doing so, and how do you plan to tackle it?

In terms of the industry, we really see potential and need for cooperation. That’s starting to be done in Fundy. There is an initiative between the berth holders and Fundy Tidal Inc, which is another local, community-scale developer there, to talk. It’s started already, in terms of workshops to identify, first, areas of cooperation.

Then further down I think we as berth holders at FORCE will team up on certain things which are now to be defined, for example geotechnical surveys, operation and maintenance facilities and environmental monitoring. It’s all things that all developers at this stage of the industry can really share; share costs and risks. That’s good for everyone, I think. 

In terms of environmental monitoring, for example, that’s pretty much common to everyone. Geotechnical surveys pretty much depend on the technology that you have. You profit in any way from that, but the amount can vary very much. But it’s at least 10 percent of the project costs. In the end, that’s a lot of money. The French coast may be different, but in Scotland and Bay of Fundy, vessel availability is a real bottleneck, for example for geotechnical surveys and for installation work.

This is really something where I think many or most developers did too much on their own, instead of cooperating. All this does not affect your competition, really. It’s a profit for everyone. And then you have a clear basis from which you start the competition.