Ocean currents: Impact on nature
Could turbines nudge a current that warms Europe?
What this tab covers What taking energy from this source does to land, water, air and climate, wildlife and ecosystems, with life-cycle emissions and land use where measured.Ocean current energy is pre-commercial, so its environmental effects are largely unknown. The main open questions are local effects on marine life and the possibility that large arrays could shift a current that carries heat across the ocean.
Effects on nature
| Area | Effect | Size | How it is reduced |
|---|---|---|---|
| Ocean circulation | Turbine arrays remove momentum and could deflect the current.4 | The Gulf Stream would likely shift its course around arrays of turbines. | Limit extraction to a small fraction of the flow; monitor current position. |
| Climate | Boundary currents carry heat poleward; effects of large-scale extraction on climate are unresolved.4 | The climatic and geologic implications of extracting energy from the Gulf Stream are not yet clearly understood. | Modelling studies before any large-scale deployment. |
| Scale of extraction | Practical extraction would be small compared with the energy driving the circulation.2 | The US technical resource (about 5.6 GW average) is under 1% of the wind's roughly 0.8 TW of work on the general circulation (calculated). | Not applicable. |
| Climate (life cycle) | No life-cycle study specific to ocean current turbines was found.6 | Nearest proxy: IPCC AR5 ocean energy (wave and tidal) median 17 g CO2e/kWh, range 5.6 to 28. | Not applicable. |
No life-cycle greenhouse gas study specific to ocean current turbines was found; the IPCC AR5 ocean energy category (median 17 g CO2e/kWh) covers wave and tidal devices, which use similar materials, so current turbines would probably be of the same order. Land use would be limited to cable landfalls and grid connections.
At sea, the likely local effects resemble those of tidal stream turbines: risk of collision for fish and marine mammals, underwater noise, electromagnetic fields from cables, and seabed disturbance from moorings, plus exclusion zones for shipping in busy corridors such as the Florida Straits. The distinctive question for ocean currents is large-scale: whether removing energy could move a current that shapes regional climate and ecosystems.
Sources
- Vertical mixing, energy, and the general circulation of the oceans (Wunsch and Ferrari, Annual Review of Fluid Mechanics 36, 281-314) Annual Reviews (copy hosted by Ifremer), 2004
- Marine Energy in the United States: An Overview of Opportunities (Kilcher, Fogarty and Lawson, NREL/TP-5700-78773) National Renewable Energy Laboratory / US DOE, 2021
- Climate Change 2014: Mitigation, Annex III, Table A.III.2 IPCC AR5 Working Group III, 2014