Environmental and Ecological Effects of Ocean Renewable Energy

A new perspective from Ocean Renewable Energy.
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  Oceanography    Vol.23, No.268 ENVIRONMENAL AND ECOLOGICAL EFFECS OF OCEAN RENEWABLE ENERGY DEVELOPMEN A Current Synthesis BY GEORGE W. BOEHLER AND ANDREW B. GILL MARINE RENEWABLE ENERGY | IN A REGULAORY ENVIRONMEN INRODUCION Renewable energy resources may repre-sent one o humankind’s best hopes or reducing our substantial contribution to global warming (Krupp and Horn, 2008). echnology to capture the energy rom wind, the sun, and biomass are all in various stages o development. In many areas o the world, marine renew-able energy has great promise but many o the approaches remain to be devel-oped to commercial standards. Energy rom marine wind, tides, currents, waves, and thermal gradients may all hold immense potential or electrical energy generation. Te development o the technology, however, is not without environmental and social concerns (Pelc and Fujita, 2002; Gill, 2005; Cada et al., 2007; Boehlert et al., 2008; Inger ABSRAC. Marine renewable energy promises to assist in the effort to reduce carbon emissions worldwide. As with any large-scale development in the marine environment, however, it comes with uncertainty about potential environmental impacts, most o which have not been adequately evaluated—in part because many o the devices have yet to be deployed and tested. We review the nature o environmental and, more specifically, ecological effects o the development o diverse types o marine renewable energy—covering marine wind, wave, tidal, ocean current, and thermal gradient—and discuss the current state o knowledge or uncertainty on how these effects may be maniested. Many o the projected effects are common with other types o development in the marine environment; or example, additional structures lead to concerns or entanglement, habitat change, and community change. Other effects are relatively unique to marine energy conversion, and specific to the type o energy being harnessed, the individual device type, or the reduction in energy in marine systems. While many potential impacts are unavoidable but measurable, we would argue it is possible (and necessary) to minimize others through careul device development and site selection; the scale o development, however, will lead to cumulative effects that we must understand to avoid environmental impacts. Renewable energy developers, regulators, scientists, engineers, and ocean stakeholders must work together to achieve the common dual objectives o clean renewable energy and a healthy marine environment.  T i    s  a  r  t  i    c  l    e  h  a  s  b  e  e  n  p u b  l    i    s  h  e  d  i    n  O  c  e  a n o  g  r  a  p h    y   , V  o l    u m e  2  3  , N u m b  e  r  2  , a   q u a  r  t  e  r  l     y   j    o u r  n a  l    o f   T e  O c  e  a  n o  g  r  a   p h   y  S  o c  i    e  t   y  . ©   2  0  1  0  b   y  T e  O c  e  a  n o  g  r  a   p h   y  S  o c  i    e  t   y  . A l    l    r  i     g  h  t  s  r  e  s  e  r  v  e  d  . P  e  r  m i    s  s  i    o n i    s   g  r  a  n t  e  d  t  o c  o  p  y  t  h  i    s  a  r  t  i    c  l    e  f   o r  u s  e  i    n t  e  a  c  h  i    n  g  a  n d  r  e  s  e  a  r  c  h  . R  e   p u b  l    i    c  a  t  i    o n , s   y  s  t  e  m m a  t  i    c  r  e   p r  o d  u c  t  i    o n ,  o r  c  o l    l    e  c  t  i    v  e  r  e  d  i    s  t  i    r  b  u t  i    o n o f   a  n  y   p o r  t  i    o n o f   t  h  i    s  a  r  t  i    c  l    e  b   y   p h  o t  o c  o  p  y  m a  c  h  i    n e  , r  e   p o s  t  i    n  g  , o r  o t  h  e  r  m e  a  n s  i    s   p e  r  m i    t  t  e  d  o n l     y  w i    t  h  t  h  e  a   p  p r  o v  a  l    o f   T e  O c  e  a  n o  g  r  a   p h   y  S  o c  i    e  t   y  . S  e  n d  a  l    l    c  o r  r  e  s   p o n d  e  n c  e  t  o :   i    n f   o @ t  o s  . o r   g  o r  T  e  O c  e  a  n o  g  r  a   p h   y  S  o c  i    e  t   y  , P  O B  o x  1  9  3  1  , R  o c  k   v  i    l    l    e  , M D 2  0  8  4  9 - 1  9  3  1  , U S  A .  Oceanography     June 201069 et al., 2009). Many countries require a comprehensive examination o potential environmental effects (e.g., or wave energy: Wilson and Downie, 2003; Faber Maunsell and MEOC PLC, 2007; and or offshore wind: MMS, 2008). Te development o various rameworks to evaluate environmental effects is underway (e.g., EquiMAR,; Simas et al., 2009). In the United States, the Minerals Management Service (Michel et al., 2007) and Department o Energy (DOE, 2009) have instituted similar efforts. In this article, we briefly review the potential environ-mental effects o development o marine renewable energy on a worldwide basis. Te consideration o environmental effects is complex; the multiplicity o technologies (Bedard et al., 2010), ocean areas, and ecosystems likely or develop-ment o marine renewable energy make a comprehensive treatment impossible in a single short article. In keeping with the goals o this volume, the scope o the present article will be limited to wind, wave, tidal, current, and thermal gradient approaches in ocean renew-able energy development (reerred to herein as ORED, adapted rom Gill, 2005). We ocus on providing examples o environmental effects that are either well documented or, where uncertainty is high, on providing appropriate sources o reerence where pertinent. Effects are discussed in the context o a ramework that crosses technology types. A FRAMEWORK FOR EVALUAINGENVIRONMENAL EFFECS Te description o environmental effects o marine renewable energy can benefit rom a classification o those effects within a ramework. In this paper, we discuss potential impacts cutting across technology types through the construc-tion, operation, and decommissioning stages as well as across spatial and temporal scales. We use a classification and ramework modified rom that used or wave energy by McMurray (2008) and place the effects o marine renewable energy development in the context o ecological risk assessment by considering stressors and receptors. ã Stressors  are eatures o the envi-ronment that may change with implementation o renewable energy during installation, operation, or decommissioning o acilities. ã Receptors  are ecosystem elements with potential or some orm o response to the stressor. Te stressors and receptors rom that ramework applied to wave energy have been modified to account or the broader approach o this synthesis. Our ocus is on the unique eatures o ORED and its interaction with the environment, and, or that reason, we only deal with issues o installation, operation, and decommis-sioning as they differ rom other marine construction projects and activities. SRESSORSScale of Stress Any stresses related to ORED need to be considered in terms o the stage o development (i.e., survey, construction, operation, and decommission; sensu  Gill, 2005), and the spatial and temporal extent o the stress, particularly its duration, requency, and intensity. For any single development, the scale is a George W. Boehlert  ( is Professor of Marine Fisheries, Hateld Marine Science Center, Oregon State University, Newport, OR, USA. Andrew B. Gill  is Senior Lecturer in Aquatic Ecology, Natural Resources Department, School of Applied Sciences, Craneld University, Bedfordshire, UK.  “ RENEWABLE ENERGY DEVELOPERS, REGULAORS, SCIENISS, ENGINEERS, AND OCEAN SAKEHOLDERS MUS WORK OGEHER O ACHIEVE HE COMMON DUAL OBJECIVES OF CLEAN RENEWABLE ENERGY AND A HEALHY MARINE ENVIRONMEN. ”  Oceanography    Vol.23, No.270 potential major actor as small develop-ments may have very localized effects, which consequently may be considered minor or even negligible (such as single devices used in testing). Effects o a large, commercially operating energy development will be at a significantly greater scale (e.g., large wind arm arrays in northern European waters will occupy several hundred square kilometers o the coastal environment). Furthermore, plans or multiple developments in adjacent waters are likely to need an even greater scale o consideration. Tey will occupy more o the coastal environment, and the survey and construction phase o development will likely extend the dura-tion and requency o stressors in the  vicinity. Hence, the cumulative effect o a number o developments could result in a different set or scale o effects that will ultimately require a different scale or set o management actions (Masden et al., 2010). Given the importance o the spatial and temporal scale in evaluating effects and impacts, we suggest that they orm the basis o any consideration o stressors relating to ORED. When assessing the environmental implications o offshore renewable energy, it is important to ollow an appropriate sequence o questioning. Figure 1 outlines such a sequence, which sets out the relationship between the OREDs and the apparent stressors and receptors that have been considered Marine Renewable Energy ( Level 1 ) WindWaveNear Shore TidalOcean CurrentOcean ThermalPhysical Presenceof DevicesDynamic Effectsof DevicesEnergy RemovalEffectsChemicalAcousticElectromagneticFieldsPhysicalEnvironmentPelagicHabitatFish andFisheriesBenthic Habitatand SpeciesMarineBirdsMarineMammalsEcosystem andFood ChainSingle/Short TermSingle/Long TermMultiple/Short TermMultiple/Long TermPopulation ChangeCommunity ChangeBiotic Process AlterationSpatialTemporalOther Human ActivitiesPhysical Structure/Process Alteration Environmental Stressors ( Level 2 )Environmental Receptors ( Level 3 )Environmental Effect ( Level 4 )Environmental Impact ( Level 5 )Cumulative Impact ( Level 6 ) Figure 1. Framework for the consideration of environmental effects of marine renewable energy encompassing different scales. Each ORED will have associated stressors that affect different receptors. Effects vary across scales and receptors; if the effects are sufficient to have impacts, those impacts can apply across different levels from population through biological and physical processes. Cumulative impacts must be considered as an additional dimension to the impacts and should consider stressors from other human impacts.  Oceanography     June 201071 through studies and the literature. Note that identiying the stressor(s) then leads to a set o receptors that may or may not show the effect(s) o the stress(es). Tere may be single or multiple stressors and single or multiple receptors; resultant effects may be short term (e.g., during construction or decommissioning) or long term (during the operational phase). Tis will have consequences or the scale o the effect and any cascading effects that are central to understanding the ecological context. Effect or Impact? When discussing stressors in environ-mental systems, an important semantic distinction should be made between an “effect” o a stressor (Level 4 in Figure 1) on a receptor and an “impact” (Level 5). Te two terms are ofen used inter-changeably, but “effect” does not indicate a magnitude or significance, whereas “impact” implicitly deals with severity, intensity, or duration o the effect. Furthermore, impact also deals with direction o effect, which means there can be positive or negative outcomes to the effect o the stressor. Te distinction between effect and impact is o crucial importance when considering ORED; a number o studies present findings that suggest or show an effect, but urther work is usually required or it to be interpreted as an impact. In terms o Figure 1, the current state o knowledge is at Level 4 rather than Level 5. In order to move rom Level 4 to 5 in Figure 1, there needs to be evidence that the effect o the stressor is significant enough to cause change that will be maniested either within a species’ popu-lation or community o species. Such impacts can occur either through direct pathways or through more indirect changes to biotic or physical processes. I there are no discernible changes to populations or communities, then it is also necessary to consider whether there may be significant alterations to ecolog-ical processes, such as trophic cascade, altered primary production, or nutrient enrichment. Such indirect effects are more difficult to determine but should be considered when determining impacts, particularly over longer periods o time or when cumulative effects o other OREDs are being incorporated (see Figure 1). Physical Presence of Devices Te mere physical presence o new structures in marine ecosystems results in undamental changes to the habitat, both above and below the water surace. Above the water surace, seabird and migratory bird impacts are o greatest concern. Marine wind energy devices will have the greatest vertical profile and the most moving parts and poten-tial effects; these effects have been addressed in several studies (Larsen and Guillemette, 2007; MMS 2008). Wave energy devices have differing profiles above water, leading to lower potential or seabird collisions, but this hazard remains to be evaluated. At the sea surace, some wave devices (e.g., Pelamis, Sea Dragon) may take up significant areas that may need to be considered or migratory surace dwellers in terms o a physical barrier. Furthermore, shoreline and estuarine devices may represent large immovable and impassable objects or migratory species and must be designed appropriately.Below water, devices will include buoys, rotors or other moving struc-tures (ocean current and tidal), cabling systems, hard-fixed structures (such as monopoles or jackets), rock scour protection, anchors, electrical cables, or pressurized pipes. In the case o land-based ocean thermal energy conversion (OEC), large pipes will extend along the ocean bottom to significant depths. Tese new hard suraces will alter bottom communities; or wave energy in particular, most oscillating devices will be deployed in “eatureless” sandy sedimentary habitats. Te physical structures will result in settlement habitat or different organisms, creating an artificial ree effect as has been the case or offshore oil and gas platorms and offshore wind arms in Europe (see benthic habitat receptor discussion). In midwater, i no anti-ouling is used, the new structure will provide settle-ment habitat and likely attract pelagic organisms, the principle that makes “fish aggregation devices” effective (Dempster and aquet, 2004). Dynamic Effects of Devices Moving parts o marine renewable devices can lead to “blade strike,” typi-cally viewed as a problem with migratory birds and wind energy devices. In-water turbines, such as current or tidal energy devices, generally move at slower speeds and thus the likelihood o blade strike is lower. However, the speed o the tip o some horizontal axis rotors could be an issue or cetacean, fish, or diving bird strikes (Wilson et al., 2007), and urther analysis is merited. An additional consideration is that the energy with-drawn rom air, water, or waves may also have potential effects in both near- and ar-field scales. Although not generally
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