Offshore wind: Impact on the biosphere

Pounding piles, fleeing porpoises and accidental artificial reefs

What this tab covers Effects on human, animal, plant, fungal and microbial life and on whole ecosystems: in the short term (construction and early years), medium term (operating life) and long term (decommissioning and legacy).

The biggest short-term impact is underwater noise from hammering foundations into the seabed, which drives harbour porpoises away for tens of kilometres. During operation, effects include seabird collision and displacement, and new hard surfaces that marine life colonises.

Deaths per TWh (wind, accidents including offshore) 0.04¹² Harbour porpoise avoidance range around noise-mitigated piling about 17 km (aerial surveys 11.4-19.5 km)¹³ Extra noise from unmitigated piling compared with mitigated piling more than 15 dB¹³ Life-cycle emissions, g CO2e/kWh 12 (median; range 8-35)⁴

Effects over time

Life affected	Short term	Medium term	Long term
Humans¹²	Marine construction risks for workers.	Low death rate per unit of energy (about 0.04 per TWh for wind, including supply-chain accidents such as helicopter collisions); competition with fishing and shipping for space.	Decommissioning work at sea; legacy of foundations and cables.
Animals¹³	Pile-driving noise: harbour porpoises avoided areas within about 17 km (standard error range 15-19 km) of noise-mitigated piling, from about 28 hours before to 48 hours after piling.	Seabird collision and displacement from feeding areas; fish and invertebrates colonise foundations and scour protection.	Uncertain; depends on whether structures are removed or left as artificial reefs.
Plants	Seabed disturbance along foundation sites and cable routes.	Algae colonise foundations near the surface.	Little evidence of effect.
Fungi and soil life	Sediment disturbance affects seabed microbes locally.	Little evidence of effect.	Little evidence of effect.
Ecosystems⁴	Local disturbance during construction.	Low life-cycle emissions (median 12 g CO2e/kWh) when displacing fossil power; fishing may be restricted within farms, which can act as de facto refuges.	Cumulative effects of many farms in one sea are still being studied.

How the effects are reduced

Bubble curtains and other noise barriers around piles reduce underwater noise by more than 15 dB, and soft starts give animals time to move away. Floating platforms and suction or gravity foundations avoid pile driving altogether. Seasonal limits on construction, careful siting away from seabird colonies and feeding grounds, and monitoring before and after construction are standard in Europe.

Sources

Climate Change 2014: Mitigation, Annex III Technology-specific cost and performance parameters, Table A.III.2 (life-cycle emissions, min/median/max) IPCC AR5 Working Group III, 2014
What are the safest and cleanest sources of energy? Our World in Data, 2024
Effects of noise-mitigated offshore pile driving on harbour porpoise abundance in the German Bight 2014-2016 (Rose et al.) Tethys, Pacific Northwest National Laboratory (report for BWO), 2019