You are no doubt familiar with solar parks and wind farms, but what about wave farms? With the disastrous implications of climate change pushing government and industry to pursue greener energy sources, there has been increased interest in solar and wind power, but another renewable is also on the rise: wave energy.
Wave farms, also called wave power farms or wave energy parks, consist of machines located offshore or nearshore that convert wave energy into electricity. The power is then transmitted to shore by subsea cables and equipment.
Experimentation with wave-power generation goes back to at least 1890, but the first commercial-scale wave farm was opened in Portugal in 2008. The 2.25 MW farm shut down two months later due to technical issues. A larger 3MW operation is planned for Scotland with enough power for 2,000 homes. Over £4 million has been allocated to the project as part of a £13 million funding investment for marine power in Scotland.
What both these efforts have in common is the use of Pelamis wave energy converters, which transform the motion of the ocean surface waves into electricity. Pelamis Wave Power, the Edinburgh-based developer of wave energy technology, relies on highly-detailed numerical simulations to analyze the performance of the machines. For many years, Pelamis performed this computational work on a small-scale cluster computing platform, leading to the current crop of second-generation Pelamis P2 machines. But for the designing of the Scotland wave farms, Pelamis sought to upgrade its computational capabilities.
Pelamis Wave Power turned to the Edinburgh Parallel Computing Centre (EPCC) to provide the extra computing muscle, specifically the organization’s dual configuration Linux-Windows HPC cluster, “INDY.” The 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,” according to a briefing from the partners.
As with other power-generation schemes, priority number one is optimizing the yield. In the case of wave farms, that means capturing as much of the wave energy as is possible. Ross Henderson, technology director of Pelamis, lays out the problem in a recent blog entry.
“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,” writes Henderson. “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.”
Henderson further explains that while there is an ultimate power limit on the amount of energy each machine can capture, the current crop of machines still have a ways to go before reaching maximum output. The supercomputing resources at EPCC will thus have a twofold purpose: to improve the control of existing machines and optimizing future designs.
“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,” continues Henderson. “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.”