While most of the tried-and-tested hardware is borrowed straight out of the offshore oil and gas toolkit, there are escalating concerns that these seafloor extraction methods will trigger irreparable damage to deep-sea biodiversity.
There are some, however, that suggest a more sustainable approach to marine mining is possible. Enter NACROM, or the North American Consortium of Responsible Ocean Mining, a group being formed to leverage recent advances in subsea robotics—driven by AI and autonomous systems—to both mitigate against potential environmental impacts of nodule collection and also drive unmatched efficiencies in terms of yield.
Swarm Technology
NACROM’s lead protagonist is Brooklyn-based Pliant Energy Systems (PES). PES is busy developing C-Ray, an AUV platform that uses undulating drives instead of propellers, making it uniquely suited to nodule collection on account of its unrivalled efficiency and maneuverability. Unlike a remotely operated crawler—which follows a “mow the lawn” pattern on the seabed—PES envisions a swarm of autonomous C-Ray AUVs that are able to discern which nodules should be removed and which should remain untouched (if they harbor life forms, for example). Individual nodules are then plucked with minimal disturbance thanks to the C-Ray’s gently undulating propulsion system.
“The evolution of undersea hardware componentry combined with rapid advances in AI is starting to prove its effectiveness for survey and inspection,” suggests Pietro Filardo, Founder and CEO of Pliant Energy Systems. “The environmental and technical challenges of nodule mining present marine roboticists with an opportunity to lead a paradigm shift towards the use of multiple semi-autonomous agents to execute large-scale operations.”
Eliminating Operational Risks Operating at the depths found in the CCZ comes with inherent risks. When a modular system fails, it results in a complete shutdown of operations and a period of costly inactivity. In short, putting all your nodules into one proverbial basket—or riser pipe—may not be the most prudent plan. Alternatively, by programming robots to place select nodules into a series of collector cages—raised to the surface with lift bags once full—operators are no longer reliant on conventional offshore assets, such as riser pipes and drill ships. Further, if a problem does occur with one or even several robots at once, they can be retrieved while the swarm continues mining, uninterrupted.
Guaranteeing Long-term Returns
The long-term challenge with ocean mining, notwithstanding the environmental debate, has always been one of economic viability. That is, how to scale operations to produce a cost-effective yield. But PES argues that C-Ray’s battery/thrust capacity could allow operators to gather more nodules, in less time, and with less energy consumption when compared to current proposals. So, this begs the question: How large a swarm is sufficient? How many robots would you need, say, to collect 3,000 tons of nodules a day?
Approximately, 235, according to Mr. Filardo. His estimate is based on BGR’s study of the Germany-backed claim area in the CCZ—where over 95% of the seabed presents an average nodule density of 14.7 kg/m²— and assumes that only 20% of the nodules are harvested (3 kg/m²). If each C-Ray is capable of covering 3m²/min (incorporating charge time), around-the-clock operation at 9 kg/min would result in a haul of 12.9 tons/day per robot.
“With a cost of $100k per unit, CAPEX on robots would be $23.5M for a 3,000 tons/day operation. If the robots are able to collect 18 kg/min, the cost falls to around $12M.”
Find out more: NACROM.org
This story was originally featured in ON&T Magazine’s August 2020 issue. Click here to read more.
