Powering wave energy
Posted: 18 Jul 2014 | 15:05
Pelamis Wave Power Ltd, the Edinburgh-based developer of leading wave energy technology, is making use of EPCC’s INDY cluster to accelerate the designs for the first wave farms.
Pelamis Wave Power generates highly-detailed numerical simulations of the hydrodynamics and control of the Pelamis machines to analyse performance and survivability.
A small-scale cluster computing platform has been used by Pelamis for many years to develop designs and control algorithms, and provide engineering load and motion data. These bespoke tools enabled the delivery of two second-generation Pelamis P2 machines, which are currently being demonstrated at the EMEC test centre in Orkney, providing a huge range of data from real sea operations. Research and development of the technology continues, so the next Pelamis design must provide another step up in performance and engineering efficiency.
The power available to a Pelamis machine depends on the incident sea conditions, but the physical design of the machine and the way it is controlled determines how much of that power can be extracted. The movements of the Pelamis machines are monitored in real time, making it possible to maximise their energy yield by controlling the power take off systems within the machine accordingly to tune their dynamic response to the changing wave conditions. Tailoring these control algorithms and settings to perform optimally across the full range of different wave conditions is key to increasing the power absorption, and therefore yield, of the Pelamis machines.
New research frontiers
EPCC’s INDY cluster offers a new order of magnitude of computing capacity to Pelamis and is opening up new frontiers of research through numerical optimisation methods that would previously have been too computationally expensive to apply.
Our first challenge was adapting our existing core simulation code to compile and run on INDY, which with the help of EPCC was less painful than expected. This allowed us to successfully demonstrate INDY with a real application, conducting batches of hundreds of simultaneously optimising simulation runs. Our next challenge is to fully integrate INDY with our simulation front-end and database tools so such batches can be conducted with auditable inputs, and maximum usability of results. We are also keen to explore the application of specialist skills at EPCC to optimise our code for faster run-times.
Wave energy is on the cusp of entering commercial service as part of the wider renewable energy marketplace. We need to impress utility customers with the very first farms and these numerical simulations will play a vital part in delivering machines that can do this. Where we have been running on 40-60 cores on our own in-house cluster, we will soon be able to run on over 1500. This means that numerical optimisation of control systems and geometry of the machines becomes tractable using our ‘virtual machine’ simulations. This is very exciting as it may open up new routes to increasing performance and reducing costs.
We already know that by increasing the volume of the Pelamis machine we can infinitely increase the power it captures, with no theoretical limits aside from the practical engineering constraints. However, there is an ultimate limit on the amount of power capture we are able to achieve from a Pelamis machine at each set volume and given geometry - a maximum energy output. With the machines which we’re currently demonstrating in Orkney, we’re still quite far from reaching that maximum output. So with the Supercomputing Scotland project with EPCC, we’re looking at both how we can improve the control of existing machines, but also optimising the Pelamis design for future iterations.
The initial demonstration studies we’ve run on INDY so far have already shed new light on the ultimate limits of wave power absorption for a given geometry of machine - and it is much higher than we’ve achieved to date. While demonstrations of the two machines in Orkney have yielded very positive and valuable test results over the last few years, there is much scope to further enhance our technology before reaching that maximum energy output.
Wave energy in general, and Pelamis in particular, offers what is perhaps the fastest cost of energy reduction trajectory of any energy technology. This is because in addition to the traditional and accepted route of cost reduction through incremental design improvements and economies of scale, we can deliver major increases in the underlying capture efficiency through control and geometry optimisation. With such a big increase in the parallel computing resources available to us we hope to optimise these aspects of Pelamis technology faster, to get closer to an ultimate absorption limit with the early commercial wave farms.
Ross Henderson, Technology Director of Pelamis
Watch Pelamis in action.
INDY is a dual configuration Linux-Windows HPC cluster aimed at industrial users from the scientific and engineering communities who require on-demand access to mid-range, industry-standard HPC. To find out more about using INDY, contact George Graham at EPCC.