The environmental impact of tidal energy devices

Dr Simon Neill
HPC Wales is supporting researchers from Xodus and Bangor University on a project to determine the environmental impact of placing marine renewable-energy devices around the Welsh coast.
The Welsh coast is over 1200 km long and its tidal range the second largest in the world – and waves offer untapped opportunities for energy generation. Current estimates place this at up to 6.2 gigawatt, or over 10 gigawatt if the potential of the Severn Estuary is included. The Welsh economy includes a thriving low carbon energy sector, employing 40,000 people and contributing £3.2 billion to the economy each year.
The Welsh Government has made a commitment to grow this sector further by capturing at least 10% of the Welsh coast’s potential tidal stream and wave energy resource by 2025.
According to Dr Simon Neill of the School of Ocean Sciences at Bangor University:
“Here in Wales we have some of the best tidal energy resources in the world, for example, in South Wales we have the tidal range of the Severn Estuary, and in North Wales we have very strong tidal currents flowing around the coast of Anglesey. By helping to develop these locations we would be bringing developers into Wales and enhancing the emerging Welsh renewable-energy sector.”
However, the deployment of the devices necessary to achieve these ambitious goals by companies such as Xodus carries risks. For example, the tidal energy arrays may alter the way in which sand is deposited along the coastline, changing the location of sandbanks that provide natural protection against storm surges. Small changes in the tidal regime as a result of a tidal energy array have the potential to cause large changes in sandbank evolution over the lifetime of the device. Dr Neill is working with Xodus to ensure that these risks are minimised:
“With Xodus Group we’re looking at how large arrays of tidal energy devices could impact on the environment – particularly at how they could impact on beaches. By studying the natural variability of the resource, we can match individual locations to individual devices and so promote this low-carbon form of electricity generation.
“To run regional-scale ocean models and to include individual devices within a tidal energy array requires a huge computational resource. Up until now we’ve had access to fairly sophisticated work stations, but we’ve only really been able to run simulations for several months, whereas we really need to run simulations for up to a decade to understand natural variability.”
Access to high performance computing provides a way to explore the timescales that Dr Neill believes are necessary to ensure that devices are deployed in a way that minimises the damage to the natural environment. Dr Steve Spall who undertakes consultancy projects for Xodus Group explains:
“We’re looking at a vast range of options for how you might build a set of tidal turbines and we want to evaluate all of those options. There can be a lot of number-crunching involved in that, so we’re using HPC Wales to allow us to do a very thorough analysis of those sorts of issues.
“High performance computing is important to this research because it allows more to be done. I think that doing these sorts of simulations on a standard computer will always be limited. There will always have to be shortcuts made in order to get to the answers, whereas we want to look deeply and we want to analyse much more thoroughly all the different options that are possible, and that requires much more computing.”
Dr Neill is already seeing large benefits to his research outputs from using HPC Wales:
“We were one of the first scientific users of HPC Wales and, in fact, the first environmental modellers to use the system. This has allowed us to run decadal simulations of wave energy across the whole of the North Atlantic and has led to our first high impact journal publication on the topic.
“Before HPC Wales, I had to spend a lot of my scientific computing time setting up and optimising model code. Now, with HPC Wales, there is a lot of support for setting up these models and I can focus my attention on analysing the model outputs and getting on with the scientific work. The support from HPC Wales is first class. The technical support is always on the end of an email, with technical queries answered usually within two or three hours.”
The work that Xodus and Bangor University are carrying out will minimise the environmental impact of marine renewable energy generation, thus helping to ensure that such devices can be deployed, further reducing Wales’ use of fossil fuels and stimulating economic growth. This work would not be possible without the huge advances in computational power made available to researchers through access to HPC Wales.