Energy & Power
Will a 12 million-gallon tank lead to better wave energy converters?
By Anthony Capkun
October 17, 2016 – One of the biggest untapped clean energy sources on the planet—wave energy—could one day power millions of homes, but more than a century after the first tests of the power of ocean waves, wave energy remains one of the hardest sources to capture. Engineers at Sandia National Laboratories in the U.S. hope to change that.
They say they are conducting the largest model-scale wave energy testing of its kind to improve the performance of wave energy converters (WECs) at the U.S. Navy’s Maneuvering & Sea Keeping facility at the Carderock Division in Bethesda, Md.
This facility houses one of the largest wave tanks in the world, says Sandia, at 360-ft long and 240-ft wide, and able to hold 12 million gallons of water.
Sandia project leads Ryan Coe and Giorgio Bacelli spend long days in the dark wave tank, where minimal lighting reduces the growth of algae. They are collecting data from their numerical modelling and experimental research to benefit wave energy technology with improved methodologies, strategic control systems design and testing practices for WECs.
“Our goal is to improve the economic viability of these devices,” said Coe. “In order to do so, we are working out ways to control the WEC’s generator to increase the amount of power it absorbs. At the same time, we are looking at how to reduce the loads and stresses on these devices in harsh conditions to, ultimately, lengthen a WEC’s lifespan in the water.”
Coe said numerous initial studies estimate that improving control of the WECs’ generators can increase energy absorption by as much as 300%. Transitioning these simplified studies to more realistic large-scale devices is the challenge at hand.
“The systems we used [for research] have been around for a while but, strangely enough, they had never been applied to [WECs],” Bacelli said. “So far, we know the techniques we are using are more efficient and cost-effective than existing methods. We are getting more information in a fraction of the time.”
Now that Sandia has completed the first round of analyses in the water, Coe said the goal is to process all the collected data to develop a new, enhanced model that will make sure the next test yields even more valuable results.
“Make no mistake, these are extremely complex machines,” Bacelli said. “They have to be fine-tuned continuously because ocean waves are constantly changing. With this setup at the Navy’s facility, we have a unique opportunity to study the problems and quantify the effects. We want to help the industry by offering solutions to the challenges the wave energy world is facing.”
Sandia’s continuing wave energy project—Advanced WEC Dynamics and Controls—kicked off in 2013 and is funded by the Office of Energy Efficiency and Renewable Energy.
— With files from Sandia
PHOTO 1: Sandia research engineers Ryan Coe and Giorgio Bacelli are collecting new information to optimize wave energy converter testing. Photo courtesy Sandia National Laboratories.
PHOTO 2: The largest model-scale wave energy testing of its kind is being performed at the U.S. Navy’s Maneuvering & Sea Keeping facility at the Carderock Division in Bethesda, Md. Photo courtesy Sandia National Laboratories.