Offshore Mobile Platform for Electrochemical Ocean Iron Fertilization & Hydrogen Gas Generation

An environmentally friendly and cost-effective solution to control global warming

Institute Reference: INV-22035

Background

The ocean is considered a large sink of atmospheric CO₂ since it can uptake 25% of the emitted CO₂ by human activities. Ocean iron fertilization (OIF) is one of the several proposed methods to sequestrate atmospheric CO₂ and mitigate its effect on the global climate. Releasing iron at the upper level of the ocean stimulates the growth rate of phytoplankton, which consume the atmospheric CO₂ and release O₂. The consumed CO₂ is proportional to the growth rate of phytoplankton, which depends on the available nutrients in the ocean such as iron. Earlier studies proposed different approaches to enhance iron availability in the ocean for phytoplankton. For example, binding the ocean iron with organic molecules enhances the iron bioavailability. However, this approach focuses only on the iron cycling in the ocean rather than increasing the ocean iron concentration through fertilization. Alternatively, biogenic iron dust, produced by chemosynthetic iron-oxidizing bacteria, can be dispersed, at altitude by an aircraft, into the open ocean. However, this approach is complex and faces restrictive legalization due to the unknown effects of dispersed dust on atmospheric chemistry. Therefore, there is no well-established technique for carbon sequestration using OIF, leading to a desire to find an efficient technique.

Technology Overview

Researchers at Northeastern have designed a novel offshore mobile platform, which transforms iron chemical compounds into ferrous forms using electrochemical processes. Ferrous is dissolved in the ocean water and used by phytoplankton. The electrochemical process is coupled with H₂ gas generation that will be collected and stored on the platform for future reuse as a fuel. The platform can be powered by any energy source including traditional electric sources, renewable energy sources, or by reusing the generated H₂.

The design of the mobile platform provides extensive control over handling, transport, and running the platform. It can be either self-operated and free-standing in the ocean, or tugged by an external device such as a ship, underwater remote operating vehicle, or any floating device. The electrode configuration and stacking can have various designs to provide more flexibility in handling the electrochemical reactions. Moreover, the electrochemical processes within the platform can be temporally varying to ensure efficient OIF and avoid any saturation in the growth rate of phytoplankton.

This electrochemical platform offers a wide range of dynamic features, which allow the implementation and engineering of different processes. For example, the platform functionality is not restricted to OIF and H₂ production but can be used in other electrochemical applications such as seawater desalination, blue energy harvesting, or mineral extraction. OIF process also provides other benefits such as a reduction in surface acidity due to the removal of CO₂ from surface waters, and the possibility for enhanced fisheries due to the increase in biomass at the base of the marine food chain.