Nonrenewable Ocean Resources: Petroleum Leads a Finite Inventory

The ocean floor harbors significant nonrenewable resources—mineral and energy deposits formed over geological timescales that human extraction depletes irreversibly. While renewable marine energy (wind, wave, tidal, thermal) gains traction, nonrenewables remain economically dominant.

Petroleum: The Dominant Nonrenewable

• Formation – Organic matter (plankton, algae) buried in anoxic sediments → kerogen → oil/gas over millions of years at 60-150°C
• Offshore share – 30% of global oil, 27% of gas production
• Key regions – Persian Gulf, Gulf of Mexico, North Sea, West Africa, Brazil pre-salt, Arctic
• Extraction – Fixed platforms, floating production (FPSO), subsea tiebacks; depths to 3,000m
• Reserves – ~230 Bboe proven offshore; decades at current rates
• Impacts – Spills (Deepwater Horizon 4.9M bbl), seismic disruption, produced water, infrastructure footprint

Natural Gas

• Often co-located with oil; dedicated gas fields (e.g., South Pars/North Field, Qatar/Iran)
• LNG liquefaction enables global trade; floating LNG (FLNG) unlocks stranded fields
• Methane hydrates (clathrates) – Vast potential resource (1,000-10,000 Gt C) but no commercial extraction technology

Seabed Minerals

Polymetallic Nodules

Abyssal plains (4,000-6,000 m): Mn, Ni, Cu, Co, REEs. Clarion-Clipperton Zone (Pacific) holds 21B tonnes. ISA exploration contracts active; mining code negotiation ongoing.

Seafloor Massive Sulfides

Hydrothermal vents (1,000-4,000 m): Cu, Zn, Au, Ag. Papua New Guinea (Solwara 1), Japan (Izena Hole), Red Sea (Atlantis II Deep). High-grade but small deposits.

Cobalt-Rich Crusts

Seamounts (800-2,500 m): Co, Pt, REEs, Te. Prime zones: Pacific prime crust zone, Mid-Atlantic Ridge.

Placer Deposits

Nearshore: diamonds (Namibia/South Africa), gold (Alaska, Russia), tin (Indonesia), titanium/zircon (India, Australia). Dredge mining established.

Extraction Challenges

• Technical – Extreme pressure, corrosion, remote operation, reliability
• Environmental – Sediment plumes, biodiversity loss (vent endemics), noise, light, toxicity
• Legal – UNCLOS/ISA regime (Area beyond national jurisdiction); national EEZs (200 nm)
• Economic – High CAPEX/OPEX; metal price volatility; ESG investor pressure

Strategic Considerations

Critical minerals (Co, Ni, REEs) for energy transition drive seabed mining interest. Circular economy (recycling, substitution, urban mining) and demand reduction offer alternatives. The ISA's "common heritage of mankind" principle requires benefit sharing—unresolved after 30 years.