Abstract
This report outlines the status of hydrokinetic power generation technology, the expected trajectory of improvement over the next five years, and recommended actions the state can take to accelerate this technology field. The report is based on numerous sources as well as data collected by ACEP over the past year at a hydrokinetic research site in Nenana, Alaska.
Turbines placed directly in river, ocean, or tidal current generate hydrokinetic power from the kinetic energy of moving water (current). The available hydrokinetic power is a function of the density of the water and the speed of the current cubed. The minimum current required to operate a hydrokinetic device is typically 2–4 knots (1–2 m/s), but optimal currents are in the 5–7 knot (1.5–3.5 m/s) range.
The Alaska region contains about 40% of the total U.S. river energy resource, 90% of the total U.S. tidal energy resource, and 40% of the U.S. continental shelf wave energy resource. Hydrokinetic turbines have frequently been discussed as an option for generating power in communities located along Alaska’s major river systems, and for tidal energy applications in Cook Inlet and coastal Southeast Alaska.
Studies by the Electric Power Research Institute indicate that hydrokinetic turbines are a viable method of generating power in Alaska. Electrical costs would range from $0.11/kWh for tidal energy in Knik Arm to about $0.68/kWh for energy from rivers near remote communities. All costs are in 2010 dollars. Ongoing studies to characterize the hydrokinetic potential of Alaskan river and tidal currents will provide improved information needed for future hydrokinetic demonstration projects.
At present, two hydrokinetic turbines have been tested in Alaska (a 5 kW turbine at Ruby during 2008, 2009, and 2010, and a 25 kW turbine at Eagle in 2010). The Eagle deployment was grid-connected, and if tests are successful, it will be converted to full commercial operation. Additional demonstration projects are planned for Cook Inlet, the Tanana River, and the Kvichak River, with other interested communities developing turbine deployment concepts.
Challenges to developing a commercial hydrokinetic industry in Alaska include determining the technological, operational, and economic viability of hydrokinetic turbines, meeting permitting requirements, and gaining stakeholder acceptance. Hydrokinetic technology can be affected by debris, sediment, frazil, and surface ice; river dynamics (turbulence, current velocity, channel stability); and the interaction of turbine operations with fish and marine mammals and their habitat. The question of turbineoperation impacts on the aquatic environment is one of the major issues that will determine stakeholder and permitting agency views toward this new technology. The 2010 hydrokinetic turbine demonstrations conducted at Ruby and Eagle were significantly adversely affected by in-river debris floating on the surface and neutrally buoyant debris. These experiences indicate that developing technology to mitigate debris problems will need to be a high priority for practical hydrokinetic power production.
River and marine hydrokinetic technology (RMHT)—an emerging technology—is at a similar stage as wind power generation technology was 15 to 20 years ago. For RMHT to move from the emerging stage to the practical commercial stage requires support similar to that provided to wind technology development during its nascent years. Financial support is needed for research to develop technology and further an understanding of the river and marine environments that will host RMHT. Data and modeling tools will be required to describe the interactions between RMHT and aquatic environments. Engagement through dialogue with all relevant stakeholders is needed at the earliest stages of project development in order to produce reasonable approaches to permitting and to develop Alaska-based expertise that is integrated with the national scene.
Alaska is well positioned to facilitate RMHT as it transitions from emerging to developed technology over the next five to ten years, by building on current and planned national and state structures. These structures include the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE, formerly the Minerals Management Service), the Department of Energy, and the Denali Commission, as well as Alaska state funding support for renewable energy projects and development of emerging technologies and research.
The one area where existing efforts and funding is lagging is the development of a science-based understanding of how fish and marine mammals will interact with RMHT. Issues of fish and marine mammals have a large stakeholder base related to ecological stewardship, economics, culture, and lifestyle that significantly affect agency views about permit requirements. Agencies have indicated repeatedly that they want to know how hydrokinetic technology will affect aquatic habitats and biology.
Five years ago, hydrokinetic technology consisted primarily of ideas in papers and studies. During the interceding five years, these concepts have been developed into actual devices and demonstration projects. Over the next five-year period, it is probable that permit requirements for demonstration projects will be well defined, several demonstration projects will be underway or completed, and initial commercial operations will have begun. Such progress assumes a continuation of the current state of high interest and activity in the development of RMHT and a continuation of support for the technology from agencies and stakeholders.