What is Holding Tidal Energy Back?

Jason Deign of Tidal Today spoke to Steven Jermy, HF4 Tidal Vessel Project Coordinator, Mojo Maritime 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?

I think the turbines are there or thereabouts. We’ve just put the Voith turbine in and it’s working pretty well. It’s a solid turbine. I think the big issue really is foundations and the installation vessels to support those foundations. There’s a big debate still in the industry about gravity base versus pile.

We’re very much in the pile camp, but I honestly don’t think the decision will be finalized until we have got a few arrays in the water. We’ve done the mathematics and we think pile works much better for any installation of any size, 40MW and beyond. What will be the key decider will be the cost of the foundation. Gravity base is likely to be much more expensive because there is more steel in them. 

I think the second issue is installation vessels. At the moment we have got anchor handlers, which aren’t up to the job. We’ve got jack-up barges. We don’t use them anymore because we had a really bad experience using one in EMEC. So in our view they are not safe. You’ve got moored barges. That’s fine with perhaps a single installation. But if you have got lots of cables underwater there is lots of risk associated with them. That leaves you with offshore construction vessels, dynamic positioning vessels, and they top out at about four knots. So if you’re in a 10-knot tidal site you just can’t use them. 

That’s why we are focused on the ship. We’ve got a ship which can work, dynamically positioned, for up to 10 knots. A little bit above that, in fact. If you’re chartering an offshore construction vessel for GBP£25,000 a day and it’s then idle for 20 of those 24 hours, then that’s not very good economics.

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?

It is such early days that it is difficult to say. To my mind we need to get arrays of 10 turbines in the water and get our operation and maintenance strategies working to find out. It is a bit like wind. Generally speaking I think the advantage you have got in tidal is you have a pretty good understanding of the upper weather limitation.

You know with absolute certainty the maximum speed the turbine has got to cope with, in terms of stream. You have got an instantaneous wave speed on top of that. The turbines will just need to be got into the water. There are quite different views about how you cope with the reversing flow. Some people have a swivelling head. Some have swivelling blades. And others have fixed blades. I don’t know which is the answer.

As regards the rest of the infrastructure, the balance of plant if you like, my guess is the cables will be the issue. Cables have been an issue in wind. But again, it’s a guess, really. In offshore wind, cable installation amounts to 80 percent of all the downtime. The tidal sites are generally much more demanding and will be much more demanding on cables than the offshore wind sites, just because of the tidal streams.

One thing the tidal energy has got is much higher power yields. The yields on average should be much higher than wind. When people realize that then they are really going to sit up and notice. To my mind, the target is getting your capital costs and operating costs down to those of offshore wind. That should be our target. If we get that, then we win on yield. Even a 3m/s tidal farm will produce more yield than an average wind farm at the same location. We just have to target those costs. I always compare us to offshore wind because it helps the financiers. But it’s not going to happen overnight. I should think we’ve got five years, really.

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?

At the moment we’re still in single turbine deployments. The first multiple ones won’t happen next year unless Tocardo gets something in, and I don’t think they will. It’s 2016 when everything is starting. You’ve got installations by MayGen. Raz Blanchard of France are planning those same dates. So that, to my mind, is when we’ll actually see pilot arrays starting. I estimate a couple of years of pilot arrays and then, if we’re successful in 10MW, we’ll see the commercial arrays after that.

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?

The answer for us is the ship. We’ve got something that we think can reduce the cost of installation from about four or five million to about a million. That’s a pretty big jump. We’re happy to take responsibility for that, but we just need a bit of help in funding it. It’s about the key stakeholders, which is industry, government and what I call the quasi-government institutions, like Carbon Trust, Green Bank and so on, taking a more active role in helping the industry make the leap. If you ask me for one expression that summarizes the whole thing, it’s ‘risk capital’. The government is, by default, assuming that the market will sort it all out.

The problem is that there are finance houses that look at these projects and it’s the Wild West, technologically. It’s extremely high risk. You can’t blame them thinking: ‘Well, we’ll just wait a bit until we start to see it work.’ We need a Manhattan Project approach, or a NASA approach. It’s not just strike rate we need, because strike rate is money in the future. Really, it is risk capital in the present, because that is what really helps people out. We’ve got a ship to build and we know it can make a huge difference.

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?

The single biggest challenge is getting the capital support we need. If we had the capital support, we could do it. I look at HS2 [a planned high-speed railway for the UK], at £40 billion, and I think if we had just £1 billion of that we could make this industry really work. But it needs people like government to put the money up and accept that some of it will end up in broken things on the sea floor.

It’s the same sort of approach you’ve got to take to NASA but the result will be unlocking an industry which can provide between 10 and 15 percent of the UK’s energy needs. I think that’s why it’s worth it. It’s not as if we need to search out for this resource. The Royal Navy has done the surveying. Unlike the oil industry, we know where it is. Unlike the oil industry, it never runs out. Unlike the oil industry, it is shallow. Unlike the oil industry, it will never pollute. It’s essentially limitless in time. 

We’re the leaders in this [in the UK] by about two years. But if we wait for everyone to catch up then we will have lost it. We will have lost the export opportunity. We could lead the world.