A review of the experience on the impacts of energy from sea (offshore wind,

wave, current-tidal, thermal) on the marine and coastal environment

Takvor SoukissianSenior Researcher

Hellenic Centre for Marine Research

Outline

1. Renewable energy sources and technologies

2. The basics

3. The spatial and the temporal scales

4. Environmental stressors & receptors

5. Conclusions

Renewable energy sources and

technologies

Renewable energy sources and

technologies

Types of renewable ocean energy (Blue energy)

1. Offshore wind energy 2. Sea wave energy 3. Tidal 4. Ocean current 5. Thermal energy

BLUE ENERGY 1

Offshore wind

1. Horizontal axis wind turbine

2. Vertical axis wind turbine

3. Floating (horizontal & vertical) axis wind turbine

Tides and currents1. Horizontal axis turbine2. Vertical axis turbine3. Enclosed tips4. Helical Screw5. Oscillating hydrofoil6. Tidal kite7. Other

BLUE ENERGY 2(1)

(2)

(3)(4)

(5)(6)

(7)

Waves 1. Attenuator2. Point absorber3. Oscillating wave surge converter4. Oscillating water column5. Overtopping6. Pressure differential7. Bulge wave8. Rotating mass

BLUE ENERGY 3

(1)(2)

(3)

(4)

(5)

(6)

(7)

(8)

Thermal gradients1. Open cycle

1a. Mist lift cycle1b. Foam lift cycle

2. Closed cycle3. Hybrid cycle

(2) (3)

(1a)(1)

BLUE ENERGY 4

BLUE ENERGY 5

Some blue energy facts

Social acceptance of renewable energy sources in Europe (Source: European Commission, 2006)

George W. Boehlert and Andrew B. Gill (2010): Oceanography, Vol. 23, No 2.

Definition of the basic constituents

Definition of the basic constituents

• Stressors are environmental features subject to change during the various stages of development of blue energy installations

• Receptors are ecosystem elements with capability of response to the stressors

Stressors and receptors

• Involved time-scales, • Spatio-temporal extent of the stress

Temporal and spatial scales

• “Effect” is a qualitative change which is a result or consequence of an action or other cause characteristic

• “Impact” is a marked effect or influence, as regards the severity, intensity or duration. There can be positive or negative outcomes to the effect of the stressor

Effects vs Impacts

The variety of

• blue energy technologies (developed, patented or under development),

• nearshore or offshore areas and ecosystems,

render the assessment of environmental effects and impacts very difficult

Effects vs Impacts

The temporal scales

The temporal scales

For the rational assessment of the construction’s potential effects/impacts on marine life, appropriate temporal scales should be defined:

• the short-term temporal scale refers to the construction and decommissioning phases (of the order of some months up to a couple of years),

• the long-term scale extends up to the operational life of the construction (of the order of some decades) and

• the “permanent” scale, which extends beyond the operational and the decommissioning phase of the construction

Design phase (1)

Activities during the preconstruction (design) phase include:

• general planning and site selection / investigation, • design of the ocean energy equipment type and the

method of installation,• consideration of removal options, • licensing procedures (including Environmental Impacts

Assessment) • design of the appropriate and necessary mitigation

measures

Information on biotic and abiotic characteristics on the considered site should be collected and assessed.

Biotic information: marine mammals, sea, resting and migrating birds, fish species, and macrozoo- and phyto-benthosAbiotic information: sediment characteristics, bathymetry and geomorphology, geological/geophysical structure at the site, as well as the general wind, wave and hydrodynamic climate characteristics of the area

Planning phase (2)

Construction phase (1)

Activities related to:

• site preparation, dredging and leveling, • piling/installation/anchoring, • cabling, and• shipping and air transports

Construction phase (2)The disturbances are related to:

• seabed disruption, • noise and • increased ship and aerial traffic in the area

Milder disturbances:

• release of pollutants, • debris and waste, • lighting, (potential effects on bird movements), and • risks related to mariners safety

Operation phase• Scheduled or non-scheduled maintenance and service

activities take place. The disturbances are related to: – the physical presence of the device and related infrastructure, – the operational noise and – the maintenance activities

• The maintenance activities result in increased traffic in the sea area and could have disturbing effects on the biota

• Maintenance and repairing materials (paints, covering, chemical substances, etc). should be treated with caution in order to avoid chemical pollution

• Potential EMF effects to some fish species, is an open debate • Bird collisions, especially in the presence of the wind turbines

along migration routes, could be another important effect

Decommissioning phaseLimited existing experience. Two options are available:

• Complete removal of the equipment: The disturbances due to the presence and operation of the equipment are completely eliminated: sediment disturbance and loss of the developed habitats during the operational life of the equipment• Leaving part of the subsurface structures in place: The installations

would act as permanent structures: any habitats that have been created and/or habitat disturbance from the physical presence of the equipment would be maintained. The foundation components shall be removed until an appropriate depth so as the remaining parts do not pose a danger for navigation

The spatial scales

The spatial scales

The site (1)

Apart of the technical specifications, the specific characteristics of a location are chosen by assessing and taking into account potential environmental and socio-economic effects. There are three different, and usually contradictory, points of view for site selection: 1) Priority to the geo-morphological and wind, wave, or sea

current characteristics of the area (shallow waters with high energy resource, ease of access to the shore and grid connections, etc.) – The engineering/technical point of view

2) Assessing all the different and legitimate marine uses of the potential sitting area along with other socio-economic effects – The socio-economic point of view

3) Assessing the potential effects/impacts that the construction is expected to have to the marine environment – The environmental point of view

• The planning phase and especially the site selection procedure is probably the most crucial and important task: the effects of this decision are expected to strongly influence the intensity and the quality of the impacts to the marine environment

The site (2)

The spatial extent (1)

• Effects of small energy developments are localized

• Effects of a single large blue energy development are significantly extended in the surrounding space

• Cumulative effects of multiple energy developments probably result in completely different sets or spatio-temporal scales of effects

The spatial extent (2)

Environmental Stressors

1. Physical presence of devices2. Dynamic effects of devices3. Energy removal effects 4. Chemical 5. Acoustic6. EMFs

Environmental Stressors

Single small blue energy developments have minor or even negligible effects

Large energy development have effects extending at a much greater spatial scale and probably temporal scale

Sea and migratory birds –Wind energy devices have the most

significant potential effects–Wave energy devices have lower

potential for seabird collisions. Surface devices may have effects to migratory surface dwellers

Physical presence of devices

Sea habitats and communities:

– The new underwater hard surfaces will affect bottom communities.

– When deployed in “neutral” sedimentary bottoms will act as artificial reefs (settlement habitats) potentially attracting pelagic organisms, (“fish aggregation device”)

Physical presence of devices

– For wind turbines - migratory birds– For underwater turbines - minor effects

Dynamic effects of devices: Blade strikes

• Kinetic energy removal/reduction from water and blockage of flow due to the physical presence of devices can lead to changes in local circulation, wave propagation, sediment equilibrium and turbulence (bottom sediment scouring and habitat changes).

• For nearshore blue energy developments, erosion and/or deposition may be affected (implications in coastal works and coastal geomorphology)

• Changes in water flow and turbulence causes changes in stratification and vertical movements of marine organisms. Removal of sufficient tidal energy may imply changes in the local tidal range

• For OTECs, impingement and entrainment of species. This is most probable for warm water intakes (potential impacts on planktonic and pelagic organisms; more general effects on fisheries).

• Deep cold water is characterized by lower diversity and biomass

Energy removal effects

• Increased marine vessel traffic implies additional risks (oil spills, etc.)

• Anti-fouling paints • For OTEC, additional concerns emerge due to the ammonia

(working fluid in the closed cycle system), nutrients (that may be discharged into surface causing algal blooms), higher heavy metal concentrations (derived from open cycle heat exchangers or from deep natural sources), alteration of chemical conditions in the discharge location, acidification effects, etc.

Chemical effects

• During the construction phase the pile driving generates high-intensity/frequency and short-duration noises

• During the operational phase underwater turbines or hydroplanes add noise to the underwater environment

• Marine mammals move away from the area where construction is taking place. At the operation phase, the mammals usually return to the area

• Some animals could be attracted to the produced noise

Acoustic effects

• Underwater cables emit low-frequency electromagnetic fields (EMFs). • EMF responses were variable between individuals and

indicated an attraction to the route of a subsurface cable • Lack of data do not allow an assessment of EMFs

impacts• There is a high degree of uncertainty as regards the

effect of EMFs on receptors• Thermal aspects of electricity transmitting cables.

Whether this small temperature change is a stressor is unknown

EMF effectsGeorge W. Boehlert and Andrew B. Gill (2010): Oceanography, Vol. 23, No 2.

Environmental receptors

Environmental receptors

1. Physical environment 2. Pelagic habitats3. Benthic habitats / species4. Fish / fisheries

• The removal of energy from water may lead to local acceleration and scouring, changes in the circulation and wave propagation patterns, sediment equilibrium, sediment transport and erosion/deposition, coastal geomorphology changes, etc.

• Currently these processes can be only simulated

• The operation of OTECs results in altered thermal regimes at sea

Physical environment

Modification of habitats by creation of new structures

1. Reduced impact on phyto- and zooplankton. Aggregation of other species and attraction of predators

2. Blade strike, collision, impingement and entanglement

3. For OTECs, impingement mortality of planktonic organisms. Stimulation of blooms due to the higher nutrient level deep water

Pelagic habitat

Habitat changes - modifications to the hydrodynamics of the area

1. The construction acts as artificial reef (stimulates some species but may negatively affect others)

2. Artificial hard bottom serves as steppingstones for species3. Placements in neutral bottoms increase biodiversity and affect

benthic communities (greater predation)4. The “shell mounds” (buoys, anchors etc.) may constitute

productive fish habitat5. Changes in the water flow from OTECs may change benthic

communities in the downslope flow. Thermal stresses may change the benthic community (coral reefs) leading to structural changes of the habitat

Benthic habitat

Fish and fisheriesChanges in species composition

1. Attraction of pelagic and benthic species, but also of predators (increased mortality of local species)

2. Potential exclusion of fishing in the area 3. Noise and EMFs effects4. Behavioral effects due to EMFs or underwater

noise (especially as regards orientation capabilities and movement patterns)

5. Migrating fishes may be also affected

Marine birds and mammals• Increase of energy used by the birds in avoiding blue energy

installations• Birds avoid wind farm installations (few records of collision)• Seabirds aggregate near blue energy sites (increased feeding

opportunities) • Changes to beach processes or tidal amplitudes affect shorebird

foraging• Lighting potentially results in collisions of seabirds

• Open issues – Spatio-temporal abundance, bird activity at night, important areas of bird activity,

migration patterns– entanglement and collision of marine mammals, mammal biology– acoustics of blue energy devices and EMF effects

The large picture

CURRENT STATE OF KNOWLEDGE

George W. Boehlert and Andrew B. Gill (2010): Oceanography, Vol. 23, No 2.

Conclusions

Conclusions

MOVING FROM THE CURRENT STATE OF KNOWLEDGE

• To understand impacts, we need to know whether an effect causes change within a population or community

• Changes refer to biotic and physical processes and may be direct or indirect

• Indirect effects are more difficult to be identified

Conclusions

• Need to address the effects of blue energy• Need to start understanding the potential impacts• Research on the environmental effects is far

behind the technological development• Need for balanced and fair environmental

standards for blue energy devices: avoid risks of environmental damage and avoid inhibiting the technological development

Top priority: MONITORING!

Question: WHEN, HOW, WHAT, WHERE?

Thank you for your attention