Motion of the Ocean Generates Fresh Water

Published on by in Technology

Motion of the Ocean Generates Fresh Water

Tim Koehler is using computational fluid dynamics modeling to help the Santa Fe, New Mexico, company Atmocean with the design of a buoy that powers a wave energy system to desalinate ocean water for coastal cities.

3bvdze7.jpg

Tim Koehler, a Sandia National Laboratories mechanical engineer, says he enjoys working with private industry through the New Mexico Small Business Assistance program. Credit: Randy Montoya

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.

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 through the New Mexico Small Business Assistance program, the two companies have tested and advanced the technology and moved it close to market by attracting significant investment. Atmocean recently signed a fourth NMSBA agreement. Small businesses can apply for help through the program once a year. “We wouldn’t be where we are today without Sandia’s help,” said Chris White, Atmocean’s chief operating officer. “It provided us with the backbone of validating our technical improvements so we could go forward.”

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.”

LITV9bw.jpg

Buoys float off the coast of Ilo, Peru. The system powers a desalination plant that provides coastal cities with fresh water.(Photo courtesy of Atmocean Inc.) 

Water arrives onshore at about 180 psi, or pounds per square inch 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. “We supply the pressurized seawater and we work with standard industry-proven technologies on the desalination,” White said.

The system runs 24/7 and production depends on wave action. White said that in southern Peru, in typical ocean conditions, 50 million cubic feet of pressurized water is pushed to shore in a year. Fourteen percent of that is desalinated, producing 5 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.”

Ocean forces on buoys

Kithil and Fullam are 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 and be as efficient as possible,” Koehler said. He is using computational fluid dynamics modeling to evaluate various buoy designs engineered by Reytek and narrowed down through wave pool tests. “I will give them an idea of ocean forces on various pump designs,” he said.

Koehler’s first foray into NMSBA has been eye-opening, he said. “It’s a different application than what I typically work on and uses different software, so it adds some breadth to my experience,” he says. “It’s been a good process in terms of my personal and professional growth. I’m learning more, and it’s nice to help a small business. I like the idea. It’s a good way to help rural communities with clean energy technology.”

After the final demonstration in Newfoundland, Atmocean, which presented the technology at the 2016 United Nations Solutions Summit, will seek a commercial partner. “If all goes well, we’re looking at a year-and-a-half after the tests to reach commercialization,” White said.

Read full article: Sandia National Laboratories

Media

Taxonomy