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Ocean/Tidal/Stream Power: Identifying How Marine and Hydrokinetic Devices Affect Aquatic Environments

Significant research is under way to determine the potential environmental effects of marine and hydrokinetic energy systems. This work, being guided and funded by the U.S. Department of Energy, is intended to address knowledge gaps and facilitate installation and operation of these systems.

By Glenn F. Cada, Andrea E. Copping, and Jesse Roberts

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 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.1,2,3,4 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.

EISA 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 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 Interior.5 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.

Artist's conception of a wave energy installation that illustrates the potential for habitat alteration, electromagnetic field effects, and entanglement with cables. (Illustration courtesy Waveplam)

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, chemical toxicity, and interference with animal movements and migrations. Designs that incorporate moving rotors or structures (tidal stream and river technologies, some wave technologies) 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.

Although some have expressed concerns about the effects of even single MHK turbines, environmental evaluations are expected to focus primarily on impacts from deployment of large numbers of units, as well as the cumulative effects of developments when added to 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 for large energy farms. In rivers, the effects of hydrokinetic turbines would occur in the context of 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, and recreational and commercial fishing.

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. 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.

DOE-supported research

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.

Artist's conception of an installation of the Open-Centre Turbine that illustrates the potential for habitat alteration, acoustic impacts, and strike. (Illustration courtesy OpenHydro)

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 National Oceanic and Atmospheric Administration (NOAA) announced eight jointly funded research awards in October 2010.6 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, DOE is funding 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).

Table 1 – Potential Environmental Impacts of Marine and Hydrokinetic Technologies and Mitigation Measures

And Argonne National Laboratory is leading a task to assess the cumulative impacts of both multiple MHK arrays and multiple anthropogenic stressors (e.g. MHK development in the presence of other shoreline development, commercial and recreational boat traffic, dredging, offshore wind farms, and oil and gas extraction).

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 under the International Energy Agency's Ocean Energy Systems Implementing Agreement. 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) of ocean energy systems are more widely accessible to the industry, governments, and the public.

Data collected under Annex IV will be housed in a searchable database called the Knowledge Management System, being developed by PNNL. Operation of the annex is shared with the Federal Energy Regulatory Commission and BOEMRE, and many countries are participating in Annex IV.

Conclusions

MHK 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, 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 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.

Table 2 – Research Funded by U.S. Department of Energy's Water Power Program to Address Impacts of Marine and Hydrokinetic Technologies

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 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 types of research and development will be important to the advancement of MHK technologies.

Acknowledgments

The authors thank Mark Bevelhimer of Oak Ridge National Laboratory for his review. Preparation of this manuscript was supported by the U.S. Department of Energy's (DOE) 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.

Notes

1 Cada, G.F., Fisheries, Volume 32, No. 4, April 2007, pages 174-181.

2 Michel, J., Worldwide Synthesis and Analysis of Existing Information Regarding Environmental Effects of Alternative Energy Uses on the Outer Continental Shelf, OCS Report MMS 2007-038, Minerals Management Service, Washington, D.C., 2007, www.mms.gov/offshore/Alternative Energy/Studies.htm.

3 Ecological Effects of Wave Energy Development in the Pacific Northwest, NOAA Technical Memorandum NMFS-F/SPO-92, National Oceanic and Atmospheric Administration, Washington, D.C., 2008.

4 Nelson, P.A., Developing Wave Energy in Coastal California: Potential Socio-Economic and Environmental Effects, PIER Energy-Related Environmental Research Program & California Ocean Protection Council, California Energy Commission, Sacramento, Calif., 2008, www.resources.ca.gov/copc/docs/ca_wec_effects.pdf.

5 Report to Congress on the Potential Environmental Effects of Marine and Hydrokinetic Energy Technologies, Wind and Water Power Technologies Program, U.S. Department of Energy, Washington, D.C., 2009.

6 www.energy.gov/news/9724.htm.


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.

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