Oak Ridge, TN, USA– A relatively new generation of waterpower technologies, broadly categorized as “marine and hydrokinetic” (MHK) energy systems, offers the possibility of generating electricity from water without dams and diversions. The potential power that could be derived from currents, tides, waves, and ocean thermal gradients is enormous, and there are numerous plans in the U.S. and internationally to develop these renewable energy technologies.
But because the concepts are new, few devices have been deployed and tested in rivers and oceans, and even fewer environmental studies of these technologies have been carried out. Thus, their potential environmental effects remain mostly speculative. Movement is under way, particularly by the U.S. Department of Energy (DOE), to perform the research necessary to address the uncertainties about the environmental effects of MHK technologies, with a view toward getting devices in the water.
Report to Congress
To address some of these uncertainties, the U.S. Congress — in Section 633(b) of the Energy Independence and Security Act (EISA) of 2007 — called for a report that addressed potential environmental impacts, including impacts to fisheries and marine resources, of MHK technologies; options to prevent adverse environmental impacts; potential role of monitoring and adaptive management in identifying and addressing any adverse environmental impacts; and necessary components of such an adaptive management program.
The EISA Report was completed in 2009 by DOE, in conjunction with the departments of Commerce and the Interior.
The report focused on potential effects of MHK technologies on aquatic environments (rivers, estuaries and oceans), fish and fish habitat, ecological relationships and other marine and freshwater resources (such as marine protected areas and recreation). It identified nine potential environmental issues (see Table 1) and outlined possible mitigation measures.
Impacts to aquatic ecosystems will occur during installation and operation of MHK projects. Installation involves placement of the generating units, mooring cables or anchors, and electrical transmission cables to shore. Possible operational environmental issues include alteration of river and ocean currents and waves, alteration of bottom substrates and sediment transport/deposition, impacts of noise and electromagnetic fields, toxicity of chemicals, and interference with animal movements and migrations. Designs that incorporate moving rotors or structures (tidal stream and river technologies, some wave technologies) also pose the potential for injury to aquatic organisms from strike or impingement.
Another broad class of ocean energy systems, ocean thermal energy conversion (OTEC) technologies, will include impacts more akin to those of steam electric plants: alteration of water temperatures, entrainment, and impingement (see Table 1 below).
Although some regulatory agencies and stakeholders have expressed concerns about the effects of even single MHK turbines, environmental evaluations are expected to focus primarily on impacts from the deployment of large numbers of generating units, as well as the cumulative effects of energy developments when added to other, existing stresses on aquatic systems. For example, impacts to bottom habitats, hydrology, or underwater noise levels that are minor for one or a few units may become significant if energy farms exploit large areas in a river, estuary or nearshore ocean. In rivers, the effects of hydrokinetic turbines would occur in the context of other impacts associated with boat traffic and water withdrawals and discharges. In the ocean, MHK developments must compete with aquaculture, offshore wind turbines, gas and oil platforms, defense-related activities, mining, merchant shipping, recreational and commercial fishing, and recreational boating.
The EISA report noted the uncertainty associated with environmental impacts of these new technologies and concluded that for some environmental issues the potential effects will prove minor and not require extensive investigation. Other issues, such as interference with animal movements and strike, may need to be monitored as part of project siting and licensing. Because potential impacts to aquatic systems will be device- and species-specific, not all issues will be a concern for every project.
Environmental Research Supported by DOE
To address these concerns and accelerate the environmentally sound development of MHK technologies, DOE is supporting a range of research and assessment activities related to the issues discussed in the EISA report. For example, in 2009 DOE issued two parallel funding opportunities for research and development on waterpower technologies. One was directed at industry partners and industry-led teams and included elements for MHK site-specific environmental studies and other projects that support market development (including research and development to address environmental issues). The second was directed at DOE laboratories to address technical challenges in water power development and market acceleration barriers. Table 2 summarizes the environmental studies that are being supported from these funding mechanisms. Most of these projects are multi-year studies that publish interim progress reports.
Also, DOE; the Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE); and the National Oceanic and Atmospheric Administration (NOAA) announced eight jointly funded research awards in October 2010. These awards are designed to address key environmental research questions surrounding ocean renewable energy and to fund the development of environmental research protocols to help provide greater regulatory certainty for developers.
In addition to issue-specific studies, DOE is funding several efforts to improve the siting of MHK projects from an environmental standpoint. Best siting practices and tools for navigating the regulatory process are being developed by several organizations:
- Re Vision Consulting LLC (Best Siting Practices for Marine and Hydrokinetic Technologies with Respect to Environmental and Navigational Impacts);
- Pacific Energy Ventures LLC (Siting Protocol for Marine and Hydrokinetic Energy Projects); and
- Dehlsen Associates LLC (Siting Study for a Hydrokinetic Energy Project Located Offshore Southeast Florida).
In addition, Argonne National Laboratory is leading a task to assess the cumulative impacts of both multiple MHK arrays and multiple anthropogenic stressors (for example, MHK development in the presence of other shoreline development, commercial and recreational boat traffic, dredging, offshore wind farms, and oil and gas extraction).
And Pacific Northwest National Laboratory (PNNL) is working to incorporate siting of MHK projects into NOAA’s coastal and marine spatial planning efforts under way around the country and providing regulatory assistance to MHK developers. PNNL also is developing risk assessments to determine the highest-risk encounters between aquatic animals/habitats and individual MHK project components.
On the international scene, DOE is leading the Annex IV project (Assessment of Environmental Effects and Monitoring Efforts for Ocean Wave, Tidal, and Current Energy Systems) under the International Energy Agency’s Ocean Energy Systems Implementing Agreement. The purpose of Annex IV is to facilitate efficient oversight of the development of ocean energy systems by expanding the baseline knowledge of environmental effects and monitoring methods. One of the primary goals of Annex IV is to ensure that existing data on environmental monitoring (and, to the extent possible, practices for environmental mitigation) are more widely accessible to the industry, governments, and the public. Data collected under Annex IV will be housed in a “smart” searchable database called the Knowledge Management System, which is being developed by PNNL. Operation of the annex is shared with the Federal Energy Regulatory Commission and BOEMRE, and many countries involved in ocean energy development are participating in Annex IV.
Burden of Proof
Marine and hydrokinetic energy technologies are new and there have been few opportunities to evaluate their environmental impacts. Whereas there is little evidence to suggest that the impacts will be large, especially for small projects, the burden of proof is on the industry to demonstrate that MHK projects can be developed in an environmentally sound manner. A number of developers and government agencies have now begun to address the issues, with the goal of resolving barriers to environmentally sound deployment and operation of MHK. Predictive modeling and laboratory studies are important, but the installation and operational monitoring of the first generation of these devices is necessary to determine whether any impacts occur and to guide the environmentally sound development of this source of renewable energy.
Typically, site-specific monitoring and research would be carried out by the manufacturer or project developer. The results may be proprietary and may be focused on particular design details or effects on a particular river, estuary, or ocean area. On the other hand, environmental questions being studied with support from DOE and other federal agencies require public dissemination of the information and are designed to be of value to a wide cross-section of the MHK industry. Integration of these two general types of research and development — the site- and device-specific environmental effects studies and the generalized laboratory, field, and modeling research — will be important to the advancement of MHK technologies.
Authors: Glenn Cada, PhD, a senior research staff member with Oak Ridge National Laboratory (ORNL), is a principal investigator in the environmental research being carried out at ORNL. Andrea Copping, PhD, is senior program manager for marine and coastal waters with Pacific Northwest National Laboratory’s Marine Sciences Laboratory. Jesse Roberts, a principal member of the technical staff with Sandia National Laboratories (SNL), is the principal investigator in the environmental research being carried out at SNL.
The authors thank Mark Bevelhimer of Oak Ridge National Laboratory for his review. Preparation of this manuscript was supported by the DOE’s Office of Energy Efficiency and Renewable Energy, Wind and Water Power Technologies Program. Oak Ridge National Laboratory is managed by UT-Battelle, LLC for DOE under contract DE-AC05-00OR22725.
|Research Funded by U.S. Department of Energyís Water Power Program to Address Impacts of Marine and Hydrokinetic Technologies|
|Environmental Issue||Research Project||Summary of Project Activities||Lead Organizations|
|Alteration of currents and waves||Benchmark Modeling of Near-field and Far-Field Wave Effects on Wave Energy Arrays||Lab experiments (wave tank) and numerical modeling of arrays at 1:33 scale.||Columbia Power Technologies, Oregon State University|
|Alteration of substrates and sediment transport and deposition||Effects on the Physical Environment — Hydrodynamics||Develop and apply hydrodynamic models that simulate the effects of marine and hydrokinetic device operation on the flow-field.||Sandia National Laboratory (SNL), Pacific Northwest National Laboratory (PNNL)|
|Environmental Effects of Sediment Transport Alteration and Impact on Protected Species: Edgartown Tidal Energy Project (Massachusetts)||Evaluate sediment transport alterations for two tidal energy technologies and effects on protected species.||Harris Miller Miller and Hanson|
|Effects on the Physical Environment — Sediment Transport Dynamics||Sandia National Laboratory sediment transport model will be applied and measurements made at a selected site||SNL, PNNL, Oak Ridge National Laboratory (ORNL), Argonne National Laboratory (ANL)|
|Alteration of water quality and food webs||Effects on the Physical Environment — Water Quality and Food Webs||Identifying potential poor circulation zones and effects on water quality and food webs.||SNL, PNNL|
|Alteration of benthic habitats||Marine and Hydrokinetic Site-Specific Environmental Studies/Information||Develop a bottom habitat survey methodology and site suitability analysis for offshore southeast Florida.||Dehlsen Associates LLC|
|Effects on the Physical Environment — Benthic Habitat Alteration||Characterize affected benthic habitats and develop habitat- and biota-specific monitoring protocols.||ANL, ORNL, SNL|
|Noise||Acoustic Monitoring of Beluga Whale Interactions with Cook Inlet Tidal Energy Project||Determine if physical presence or noise from Ocean Renewable Power Company tidal device alters beluga whale distribution, abundance, and behavior.||Ocean Renewable Power Company Alaska LLC|
|Active Acoustic Deterrence of Migratory Whales||Test an acoustic deterrent system to discourage gray whales from entering wave energy parks.||Pacific Energy Ventures LLC|
|Acoustic Effects of Hydrokinetic Tidal Turbines||Determine background noise in Admiralty Inlet, Wash., acoustic footprint of a tidal turbine, and effects of noise on aquatic animals.||Public Utility District No. 1 of Snohomish County|
|Effects of MHK on Aquatic Organisms — Acoustic||Acoustic measuring devices will be developed to characterize ambient and marine and hydrokinetic-generated noise. Response of aquatic organisms to predicted marine and hydrokinetic noise levels will be assessed.||ORNL, SNL, PNNL|
|Develop Active Acoustic Detection System for MHK||Develop, integrate, test, and operate a full-scale acoustic detection system for marine life and debris.||Scientific Solutions Inc.|
|Electromagnetic fields (EMF)||Effects of MHK on Aquatic Organisms — EMF||Laboratory and field studies of the effects of constant and variable magnetic fields on behavior of aquatic organisms.||ORNL, PNNL|
|Chemical toxicity||Effects of MHK on Aquatic Organisms — Toxicity||Conduct leaching and toxicity tests of anti-biofouling chemicals.||ORNL, SNL, ANL|
|Development of a Coating for Coating Underwater Surfaces||Develop an innovative, non-toxic surface coating to prevent biofouling||Semprus Biosciences|
|Interference with animal movements and migrations||Effects of MHK on Aquatic Organisms — Attraction to and Avoidance of Devices||Identify potential interactions of migratory and resident aquatic organisms with marine and hydrokinetic devices and provide monitoring guidance.||ORNL, PNNL|
|Collision and strike||Assessment of the Environmental Effects of Hydrokinetic Turbines on Fish: Desktop and Laboratory Flume Studies||Lab flume studies of hydrokinetic turbine designs to estimate the probability of blade strike and injury to fish.||EPRI, Alden Research Laboratory,
Conte Anadromous Fish Research Laboratory
|Effects of MHK on Aquatic Organisms — Physical Interaction with Devices||Assess strike risk for marine and freshwater animals and conduct strike studies in flumes and field sites.||ORNL, PNNL|
|ORPC Strike Study||Assess the potential for fish to interact with the Ocean Renewable Power Company turbine-generator unit in the Bay of Fundy||University of Maine|
|Impacts of Ocean Thermal Energy Conversion (OTEC)||The Potential Impacts of OTEC Intakes on Aquatic Organisms at an OTEC Site under Development on Kauai, HI||Provide the baseline biological data required to determine the potential impact.||Ocean Engineering and Energy Systems International Inc.|
|Enhanced Numerical Model of OTEC Discharge Plume||Model will quantify relationships between OTEC discharge design, performance, and environmental changes.||Makai Ocean Engineering Inc.|
|Potential Environmental Impacts of Marine and Hydrokinetic Technologies and Mitigation Measures Table 1|
|Environmental Issue||Potential Impacts||Potential Mitigation Measures|
|Alteration of currents and waves||Reduced velocities and wave heights may affect water mixing, sediment and plankton transport, and bottom and coastal habitats.||Avoid siting in sensitive areas. Streamline shapes and reduce size of non-generating structures. Optimize spacing between units to minimize far-field changes.|
|Alteration of substrates and sediment transport and deposition||Installation may disturb sediments, possibly degrading water quality. Reduction of current velocities or tide heights during operation may alter sediment scour and deposition.||Avoid siting in areas with contaminated sediments. Use installation techniques that minimize sediment disturbance. Streamline shapes and reduce sizes of non-generating structures.|
|Alteration of benthic habitats||Installation will displace bottom-dwelling organisms. Changes in currents, waves, and sediment transport may alter plant and animal habitats.||Avoid siting in sensitive areas. Minimize disruption by subsurface drilling/boring or burying cables in narrow trenches. Minimize footprint of anchors.|
|Noise||Noise from pile-driving and other installation activities could injure or kill nearby organisms. Operational noise could disrupt animal behavior.||Use sound insulation during installation and for generating devices. Avoid sensitive areas and/or seasons. Employ acoustic deterrent devices.|
|Electromagnetic fields||Generating devices and transmission cables will produce electric and magnetic fields that could alter animal behavior.||Avoid siting in critical migratory paths. Use shielding to prevent leakage of electrical current and reduce electromagnetic fields.|
|Chemical toxicity||Accidental leaks of hydraulic fluids or erosion of coatings to control biofouling may have toxic effects on organisms.||Use non-toxic paints and oils, including use of water-lubricated devices. Use non-biocidal foul-release coatings. Mechanical removal of biofouling organisms.|
|Interference with animal movements and migrations||New structures may attract animals, affect fishing, create roosting/haul out sites, cause entanglement, or constitute a barrier to migrations.||Avoid siting in sensitive areas. Space individual units to allow passage. Use thick, taut mooring lines. Minimize horizontal surfaces above waterline and attractive lighting to minimize interactions with pinnipeds and birds.|
|Collision and strike||Organisms may collide with project structures. Blade strike or screen impingement may cause mortality.||Optimize blade design to minimize injury. Make device conspicuous to maximize avoidance.|
|Impacts of ocean thermal energy conversion (OTEC)||May change temperature and water quality in surface waters. Biocides and heat exchanger metals could cause contamination. Losses of aquatic animals to entrainment, impingement, and cold shock.||Avoid siting in sensitive areas. Use discharges for aquaculture, desalinization, and agriculture. Minimize intake velocities. Optimize discharge locations. Employ intake screens.|