BMED System: New Electrochemical Technology to Combat Ocean Acidification, CO2 Emissions

A groundbreaking innovation shows potential in addressing the threats of ocean acidification, providing hope for safeguarding the balance of marine ecosystems.

Looming Threat to Marine Life

Only 45% of CO2 emissions remain in the atmosphere, and the rest is either stored in plant matter and soils through the biological carbon cycles, or absorbed from the atmosphere into the oceans. Each of these cycles accounts for 25% and 30% of emitted carbon dioxide, respectively.

Carbon dioxide that dissolves in the water reacts to form chemicals that increase ocean acidity. During the process of geological weathering, this acidity can be counterbalanced by the dissolution of minerals from rocks along coastlines. However, the rate and volume of CO2 emission has extremely increased over the last 60 years. This has far exceeded the rate of geological weathering, resulting in a 30% increase in ocean acidity.

Ocean acidification is currently one of the serious threats to marine ecosystems. As it disrupts the delicate balance of ocean chemistry, it can have a devastating impact on marine life, from tiny plankton to shellfish and coral reefs. In order to combat the dangerous effects of global warming, humanity must accelerate the efforts to reduce carbon emissions and rapidly scale strategies to remove CO2 from the atmosphere and the oceans.

Promising Tool for Ocean Restoration

Fortunately, it is possible to reset the pH level of the oceans using a process called ocean alkalinity enhancement (OAE). This rebalancing technique can also encourage additional carbon dioxide to be absorbed from the atmosphere. As long as the ocean's alkalinity is carefully and continually restored, ocean acidification and excess atmospheric CO2 concentration can be addressed simultaneously.

The most obvious technique to do this is to add finely ground alkali minerals into the oceans to lower the acidity of the water directly. However, the massive scale at which this strategy would be enacted is staggering.

At McMaster University, experts believe that one of the best ways to fight ocean acidification is through an electrochemical approach operated on decarbonized energy. This will be done by conducting bipolar membrane electrodialysis (BMED) to directly remove the acidity of seawater without adding other substances.

BMED technology requires only electricity, seawater, and specialized membranes. The simplicity and modularity inherent to this approach allows a scalable, flexible, and potentially cost-effective method of removing carbon dioxide.

Scientists from McMaster University collaborated with experts at the Palo Alto Research Center and X Development to build and test a small-scale BMED system. The system performed well as expected and showed great promise when coupled with existing facilities like desalination plants.

The research team identified the primary technological limitations of BMED technology when it was created in 2015. It is somehow limited by the specialized membranes which have short lifetimes since they are susceptible to degradation.

The recent work aims to create scalable, ultra-thin membranes for use in a modified BMED process. It also expects to identify optimal industrial coupling, efficient operational conditions, and ideal global locations to implement OAE technology around the world.