Quantifying the Potential and Risks of Large-scale Macroalgae Cultivation and Purposeful Sequestration as a Viable CO2 Reduction (CDR) Strategy

Default ARPA-E Project Image

OPEN 2021
Santa Barbara, California
Project Term:
07/29/2022 - 07/28/2025

Technology Description:

The University of California, Santa Barbara (UCSB) will investigate the efficacy and impact of removing up to 0.1 Gt CO2/yr from the atmosphere and surface oceans through cultivating and sinking fast-growing macroalgae. The UCSB team has previously determined using sophisticated oceanographic models that sunken biomass will sequester the fixed carbon for more than 100 years on the ocean floor if certain conditions are met. The scale of the cultivation needed to sequester 0.1 Gt CO2/yr is similar to the size of the biofuel feedstock farms proposed by ARPA-E’s MARINER program, suggesting that with technological advancement, macroalgae cultivation and sequestration may be an economically viable CDR strategy. The team will quantify the long-term biogeochemical and ecological outcomes of large-scale macroalgae cultivation, assess the sequestration time scales of macroalgal carbon, estimate its environmental impacts on the ocean interior and seafloor, and identify the most effective method to convey the biomass to the ocean floor.

Potential Impact:

The technology will provide the understanding to leverage large offshore macroalgal aquaculture as a potential CO2 reduction strategy and comprehend its biogeochemical fates, sequestration permanence, and ecological impacts. This proposed CDR method will:


Enhance the energy security of the US through the mitigation of climate change


Reduce greenhouse gas by sequestering atmospheric CO2 for more than to 100 years


Assist in enabling macroalgae to become competitive with other technologies for direct air capture. Once advanced farm scale reaches the order of 10,000 ha, production costs below 100 USD tonne-1 CO2 sequestered may be possible.


ARPA-E Program Director:
Dr. Simon Freeman
Project Contact:
Dr. David Siegel
Press and General Inquiries Email:
Project Contact Email:

Related Projects

Release Date: