Recent studies 1, 2 have begun to shine a light on an exciting carbon dioxide removal approach called Ocean Alkalinity Enhancement (OAE). This cutting-edge approach capitalizes on an opportunity to treat wastewater with alkaline minerals before it’s discharged into ocean waters. Unlike many nature-based climate solutions, OAE has the unique quality of actively countering the acidity of ocean water. It increases the ocean’s capacity to absorb CO₂ from the atmosphere. Researchers have calculated that this technique has the potential to sequester approximately 18 teragrams of CO₂ annually. This is more than 18 trillion grams on a global level!
The OAE process makes urgent sense in our current reality, where anthropogenic CO₂ emissions have reached catastrophic levels. The resulting survey findings tell an astonishing story. The space between the lines of latitude 20°N and 60°N captures an extraordinary 79.3% of the world’s potential for OAE. This would include the European Union, the United States, and China—the three largest economies in the world. Combined, they account for more than half of this untapped potential, underscoring the critical need for impactful carbon removal solutions in these areas.
Understanding Ocean Alkalinity Enhancement
Ocean Alkalinity Enhancement is an experimental technique that aims to bolster the chemical make-up of ocean waters. OAE first neutralizes wastewater with alkaline minerals pumped offshore before releasing it into the ocean. This process helps to reverse the effects of ocean acidification. That decrease in acidity helps to reduce the concentration of CO₂ at the water’s surface. Because of this, the ocean has to take up more atmospheric CO₂.
Research shows that OAE can have a multi-fold effect on improving carbon sequestration. According to recent research, coastal wastewater-based ocean algal biomass can be a highly impactful global carbon sequestration tool. This would allow it to sequester approximately 18.8 ± 6.0 teragrams of CO₂ per year. This substantial figure reflects the enormous opportunity that exists in utilizing wastewater treatment plants located near ocean coastlines to enhance carbon capture capabilities.
The mechanism underlying this process is the rapid alkalinization rate sustained through olivine dissolution in aerobically treated wastewater. The recent solvent screening work showed that this reaction occurs around 20.5 times faster than in typical seawater conditions. This is what makes Ocean Alkalinity Enhancement (OAE) such an energy-efficient method of removing carbon dioxide.
The Role of Carbon Dioxide Removal Strategies
Ocean Alkalinity Enhancement also falls under the wider umbrella of Carbon Dioxide Removal (CDR) strategies. These strategies encompass a diverse range of techniques aimed at capturing CO₂ from the atmosphere and ensuring its long-term storage. Most CDR techniques focus on anaerobic or oxygen-free environments. Unlike other similar practices, OAE provides a new implementation methodology by capitalizing on aerobic environments.
The majority of CO₂ emissions originate from regions rich in oxygen. As such, it’s important now more than ever to test innovative methodologies that could work under these constraints. OAE’s ability to alkalize wastewater before it’s discharged into oceans offers a dual benefit: it addresses wastewater management challenges while contributing to carbon sequestration efforts. This new role for environmental management in climate action not only offers an intersectional space for creative climate solutions to flourish.
Implications for Future Research and Policy
The implications of Ocean Alkalinity Enhancement are much broader than its direct carbon sequestration potential. As nations work to achieve their climate pledges, moving forward, we feel that supporting the adoption of OAE would be a promising strategy to advance new environmental policies more effectively. The potential to combine wastewater treatment and climate mitigation would make a strong case for investment in both technology and infrastructure.
Future research will be indispensable in determining the long-term impacts of OAE on ocean ecosystems. It will assist in ensuring that implementing OAE does not have unintended negative impacts on aquatic life. Soon, other research will focus on how to refine the process to increase the amount of carbon captured while keeping costs down.