NREL’s Desalination Device Makes Waves

In 2019, the U.S. Department of Energy initiated the Waves to Water Prize. The contest’s goal was to encourage the development of small desalination systems which could help coastal communities in times of climate disaster and recovery and also to help provide clean drinking water to areas where water is scarce. In April of 2022, after 114 teams entered the contest, a winner was crowned: Oneka.  

But as competitors were creating their boats, the National Renewable Energy Laboratory (NREL) was building its own small craft, called the hydraulic and electric reverse osmosis (HERO) wave energy converter (WEC) device, intended in part to mitigate the risk of wave energy tech. 

“Wave energy is a fairly nascent technology with a very aggressive learning curve,” said Scott Jenne, multi-disciplinary research engineer at NREL. “By providing it as an open-source design it will give others something to build off of and reduce the learning curve.”

The purpose of the competition was to help design a floatable desalination craft that, in times of crisis, can turn salt water into drinkable water using wave energy, and that can be put into action quickly. With 114 entrants, the desalination market is robust. 

The desalination of water could be a crucial technology for a future where fresh water is increasingly limited. The Carlsbad Desalination Plant in San Diego produces about one million gallons of drinkable water every day, but this is at a huge scale. What NREL and the competitors are building are small-scale devices that are relatively easy to install. And this might help with municipal water needs. 

“It takes a lot of energy to make drinkable water from the ocean,” said Jenne, “but using wave energy there is an opportunity to make that water cost effective, emission free, and the natural mixing of a wave climate makes the brine discharge and other environmental effects much easier to manage than some other desalination technologies.”

In August 2022, NREL sent the craft back out into the ocean off of North Carolina to explore different technology in the boat, with a third deployment coming soon. There is a lot to learn before small desalination devices can be regularly used. 

“We are also researching what is needed for technologies that would be more permanent installations for applications like municipal water supply… they’ll need to be much larger and much more reliable in order to be cost competitive,” said Jenne.

One of the other goals of the research at NREL is to see how the device can be scaled up. 

“Wave Energy technologies actually get more efficient as you increase their size, up to a point,” Jenne said. “An ideal WEC is about 5-10 times the size of our WEC. You can also put more of them in an array (like a wind farm). Desalination systems are very scalable, you basically just add more membranes.”

For now, NREL will put its device back out into the ocean off of North Carolina, as the lab, along with private companies, figures out a way to bring fresh drinking water at small scales to the communities that need it.