publications

Publication : Future policy implications of tidal energy array interactions

This is an unusual one for me so far, in that it contains no new science. Instead, it explores some of the policy implications of what we already know about how tidal farms will affect the flow in their channels, and affect each other, if they are deployed at large scales.

There are two main points that we’ve tried to get across:

  • Firstly, that if we are to achieve the greatest possible energy yield for a given level of environmental impact, we’ll need to strategically plan tidal developments for a whole region – not do them piecemeal.
  • Secondly, that tidal farms will interact. If they’re upstream and downstream of each other that interaction is detrimental, but if they’re side by side then they can have mutually beneficial effects. We think it’s a problem unique to tidal power that if one array stops working, its “rival” neighbor can lose power… and that raises a number of fun and interesting questions about management and liability.

After looking at the physics and the resulting policy issues, we discuss some ways of dealing with them. We argue that if we want to get the most that we can out of our seas we will need some form of interventionist, centrally planned, approach to managing tidal power; the free market will not deliver. The arrangements that we have at the moment are just fine while we’re only putting a few turbines in the water. But as we scale up – and we must scale up, if tidal energy is going to be significant at grid level – this stuff will start to matter, and it’d be really nice if the necessary policy frameworks were in place before they’re needed.

Diagram showing interactions between tidal farms in series and in parallel
Diagram summarizing some possible inter-array interactions. See my figure-making skills! The version in the paper doesn’t include the faces, which I added for a presentation, but in hindsight I wish it did!

I’m proud of this one, for two reasons: Firstly that I think it’s important, in that it asks some questions that I don’t think anybody in the marine spatial planning, policy or governance spaces has been thinking about much as yet (although I gather they have been grappling with similar issues around wind). Secondly because it’s been a genuine multidisciplinary, collaborative, process. I had the original idea for the paper a couple of years ago, and after discussion with one of the other authors we tried to flesh it out, but we realised that we needed people with policy expertise. We brought them on board – including Steph Weir, a former PhD officemate of mine who wrote major chunks and taught me about unitization – and the result is a pleasingly short paper that really couldn’t have existed without all five of its authors.

If you want to read the whole thing yourself – it’s only five pages long, and it’s written for a non-specialist audience – then you can get the official version here with a subscription to Marine Policy, or the unformatted, post-review, version here for free.

Posted by simon in Explaining my work, Publications

Publication, of a sort… a corrigendum.

Everybody in academia receives email spam, much of it from China, inviting us to conferences that, if they exist, we probably don’t want to go to. One ignores it, and hits “delete”. Late last year I was about to do that when I realised that on this occasion, it was a genuine email from a Chinese PhD student who was using some code that I had published, and asking for help with it. Great!

I couldn’t immediately understand why the code wasn’t working for this student, so I asked him to send his files to me… and I found a bug in my code. With a growing sense of dread, I realised that this bug would have affected results that were already published. I notified my co-authors on the paper and in haste, on evenings and weekends (because this was not my full-time job at the time), I corrected the code, reran a hydrodyanamic model, redid the analysis… and found to my relief that the overall conclusions of the paper were not affected and so there would be no need for a retraction. It did, however, feel as though the record should be corrected, so I got in touch with the editor, and… long story short, a “corrigendum” to the original paper appeared online today. For those without a subscription to Ocean & Coastal Management, I’m also hosting it here for now.

I was already an advocate for good software development practices in science, in order to reduce the liklihood of exactly this sort of thing, and now my feeling on this matter is strengthened…

If you have been using my code for inserting tidal turbines into Delft3D you should make sure that you are using the current version, which had this error fixed in December 2017.

Posted by simon in Publications

EIMR, and future wave resource

This week I am at a conference on Environmental Interactions of Marine Renewables (EIMR), in Orkney. It’s the kind of event that covers quite a broad area, and most of it isn’t in line with my “interests” in a narrow sense – but the breadth makes it really helpful for talking to a wide range of people, and hearing about a wide range of research.

The majority of the research here is about the effects that renewable energy extraction will have on the environment, which is certainly an important topic. A few, including my own poster, look at “environmental interactions” in the other direction, in my case asking “how will the wave power arriving at the west coast of Orkney change, as the planet warms in the future?”

It’s only a short, preliminary look at the problem, and it has a high level of uncertainty attached. However, it looks as though the change between now and 2100 will be small. That’s good news for wave energy developers.

  View poster

 

Posted by simon in Explaining my work, Publications

Two new publications

I’ve had two publications appear online in the last few weeks, in the opposite order to that in which I actually did the work. They have a lot in common, using similar methods in different locations, so I thought I’d write about them together.

The most recent is my second journal article as lead author, and one that I’m quite proud of. It covers the work that I did in Japan last year, and in the months after returning, on the tidal energy resource of the Goto Islands of Nagasaki Prefecture. We produced estimates of the amount of power that could be obtained – which is mostly of interest for the people planning tidal development in that archipelago – but of more general interest are the findings about inter-channel interactions. The Goto Islands have several parallel channels that could contain turbines.  When this arrangement has been studied in other places, it has usually been found that putting tidal turbines in one channel causes flow to divert into the others, and hence that to reach the full potential for power we would have to put turbines in every channel. Goto doesn’t behave like that – instead, the channels have very little effect on each other – and in the paper we looked a little into why that is. My thanks are due, of course, to my co-authors on this work, both in Scotland and Japan.

 

Plot showing the mean power produced by different numbers of turbines in the Goto Islands.

Plot showing the mean power available from various numbers of turbines in the channels of the Goto Islands, using simplified M2 tides.

Just a few weeks ago I attended the EWTEC conference in Cork and presented this paper on Lashy Sound, which is a channel with strong tides in the Northern part of Orkney. In this work, I used very similar methods to those that were developed in Japan to look at the tidal resource – in this case, not for realistic turbine developments but in terms of the theoretical maximum available power if we didn’t care about things like environmental impact, or allowing ships through. Unsurprisingly, it looks like achieving this maximum yield would have some significant impacts. I also considered the more plausible scenario of a smaller tidal farm, similar to the 30MW one that has been planned for the area, and was able to show that its effects would be small and confined to Lashy Sound itself – something that’s important when other potential tidal energy sites are just a few km away in neighbouring channels.

Both of these papers are available for free at the links above, or at the publications page on this site.

Posted by simon in Explaining my work, Publications, Working in Japan

First journal article!

Well, sort of. My last post also listed two journal articles but I was a minor author on those, contributing a small part of the text and comments on the rest. This post is about my first article as lead author.

It’s called “Implementation of tidal turbines in MIKE 3 and Delft3D models of Pentland Firth & Orkney Waters”, and it describes work that myself and two groups at Heriot-Watt and Edinburgh Universities did a few years ago, near the start of my PhD. Lots of people have represented tidal turbines in regional-scale flow models, but most of them have used academic codes that industry and investors won’t trust, or have modified trusted code – which itself tends to undermine that trust. Our aim for this work was to look at how tidal energy extraction can best be represented in two widely-used commerical modelling suites, without modifying their code. We also did some actual modelling, by way of example, and the results of that have been passed on to others in the project to use for ecological work.

In a small way this was perhaps a baptism by fire, in that I had to pull together work and writing done by people far senior to myself, add my own work on top of each, and try to construct a single coherent publication. Perhaps partly for this reason, coupled with my own inexperience, it had a long journey through review… but it’s out there now, and I’m glad it’s done!

If you have a subscription to Ocean & Coastal Management you can read the published version here; otherwise the “accepted version” (without journal formatting) is available at this finely crafted link.

Posted by simon in Publications, Reflective