The team includes members from Arizona State University, University of California-Irvine, and the National Renewable Energy Laboratory (NREL).
“Removing carbon dioxide from the ocean is tricky, but leveraging a similar existing technology through desalination could make it much more feasible,” said Hornbostel. “We’re looking for an alternative that saves both energy and costs.”
The most common method for direct ocean capture relies on an electrochemical cell. Though effective in removing carbon dioxide, using electrochemical cells is energy-intensive and expensive. Hornbostel and her team are looking to prove that coating desalination membranes with special chemical groups can effectively “bubble off”– or release – carbon dioxide gas for capture and storage or reuse, similar to when a carbonated beverage is opened.
“Using our approach should require far less electricity to strip carbon dioxide from seawater compared to more conventional methods that electrochemically split all of the incoming seawater into basic and acidic streams,” explained Hornbostel.
But first, the team will have to determine what membrane is best for the bubbling off to work.
The team will study both reverse osmosis (RO) and nanofiltration (NF) membranes. The NF membranes have a lower energy input, but a lower carbon dioxide removal rate. The RO membranes have a high carbon dioxide removal rate, but a high energy input.
“We’re planning to run a technoeconomic assessment that will allow us to compare these two options and determine which one is more scalable outside of a lab setting and at an actual desalination plant,” said Hornbostel.
The two-year project – Coupling Desalination with Novel Marine Carbon Dioxide Removal Membranes – will also be led by co-Principal Investigators Professor Matthew Green, Arizona State University; Professor Jenny Yang, University of California-Irvine; Dr Abhishek Roy, National Renewable Energy Laboratory; and Dr Mou Paul, National Renewable Energy Laboratory.