Motion of the Ocean Generates Fresh Water

Hurricane Katrina whipped up huge, powerful waves that caused severe destruction in 2005 along the U.S. Gulf Coast. Their size and strength convinced Phil Kithil of Santa Fe, New Mexico, there had to be a way to harness that energy.

His first thought was a device that would use wave action to pump deep, cold seawater to the surface to dampen the intensity of hurricanes, which thrive on warm water. He proved the concept with a simple tube and one-way valve attached to a buoy, but the idea had no commercial potential, as hurricanes are unpredictable.

He thought of a second use because the wave-action pump also brought to the surface concentrated ocean nutrients such as phosphate and silicate that promote the growth of phytoplankton. “Phytoplankton take in carbon dioxide to metabolize nutrients and give off oxygen,” Kithil said. “We felt the pumps had a role to play in climate change mitigation.”

But, again, the business potential evaporated when governments participating in the 2009 United Nations Copenhagen Climate conference did not take action that would open carbon markets for the device.

His third idea was the charm. Kithil and his company, Atmocean Inc., founded in 2006, partnered with the Albuquerque engineering firm Reytek Corp. in 2010 to produce a pump system that uses wave power to send pressurized seawater onto shore where it is desalinated without the use of external energy. Kithil said the system has a simple design and can be set up cheaply and in rural settings to provide fresh water for drinking and farming in coastal cities.

Working with scientists at Sandia National Laboratories, the two companies have tested and advanced the technology and moved it close to market by attracting significant investment. 

Kithil and Phillip Fullam, chief engineer of Reytek, first worked with Sandia Labs’ Rick Givler, a specialist in modeling physical systems, to assess the feasibility of their near-shore wave energy system. Givler proved that, using typical waves and a set number of seawater pumps, considerable pressurized water would reach an onshore reverse osmosis water purification system.

“We needed to know if we would get a dribble at the end or a gusher of pressurized water,” Kithil said. “Rick came up with the answer — a gusher. If it was a dribble we’d have no business. With a gusher we could estimate expenses and profit. That’s how important the Sandia research was. We could take an interesting idea to business feasibility.”

Sandia Labs’ findings have helped Atmocean attract about $3.5 million in investment to continue product testing, add staff and boost component manufacturing at Reytek. The company built full-size seawater pumps and tested the system off the coast of Oregon in 2011 and off Peru for six months in 2015. “The first Peru tests were a big success,” Kithil said. “Other small communities want to see if it will work for them.”

Atmocean is working now with Sandia Labs engineer Tim Koehler on computational modeling of the wave energy system. Following trials in a test tank at the Texas A&M University Haynes Laboratory, the system will be deployed later in the year off the coast of Newfoundland for a third round of testing that will demonstrate the prototype in an operational environment.

Atmocean’s system is a 200-foot by 200-foot array of pumps floating on the ocean. “Each pump is a buoy on a piston,” Koehler said. “As a wave passes, the buoy ingests sea water, and as the buoy settles, it pumps seawater through hydraulic lines back to shore where it enters the zero-electricity desalination process.”

Water arrives onshore at about 180 pounds per square inch (psi) of pressure. Atmocean uses energy recovery devices — essentially spinning mechanical wheels — to boost 14 percent of the arriving seawater to 900 psi, the pressure needed to run reverse osmosis. The system is the size of a shipping container and is manufactured by Atmocean industry partners. 

The system runs 24/7 and production depends on wave action. In southern Peru, in typical ocean conditions, 50 million cubic feet of pressurized water is pushed to shore in a year. 14 percent of that is desalinated, producing five million cubic feet of fresh water annually that can be used for agriculture or consumption.

Kithil said the system is inexpensive to operate, offers local employment and helps the environment. “Each array of pumps creates a defacto marine protected area with artificial structures that see marine growth,” he said. “The system uses small boats operated by local fishermen who get consistent work. During our full-scale pilots in Peru in 2015, we saw a huge outpouring of support from the local fishing community.”

Kithil and Fullam are now working with Koehler to improve the pump design. They want to know what forces the ocean, through the passage of waves, puts on the buoys so they can optimize their performance.

After the final demonstration in Newfoundland, Atmocean, which presented the technology at the 2016 United Nations Solutions Summit, will seek a commercial partner.