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Physical and Ecological Evaluation of a Fish-Friendly Surface Spillway
AbstractSpillway passage is one of the commonly accepted dam passage alternatives for downstream-migrating salmonids and other species. Fish passing in spill near the water surface have improved chances of survival than fish that pass deeper in the water column near spillway structure. In this study, an autonomous sensor device (Sensor Fish) was deployed in 2005 to evaluate fish passage conditions through the Removable Spillway Weir (RSW) at Ice Harbor Dam on the Snake River in south-central Washington State. RSWs enable fish to pass in spill nearer the water surface compared to conventional spillways where spill discharge is controlled using tainter gates. The RSW study was undertaken concurrently with a separate live fish injury and survival study. Conditions at the RSW–Spillway transition and deflector region were found to be potentially detrimental to fish. As a result, the spillway slope and deflector radius were modified, and the efficacy of the modifications was evaluated in 2015. The frequency of severe acceleration events (acceleration =95 G) during passage decreased significantly (from 51% to 35%; p-value = 0.049), and collisions with structures decreased from 47% to 27% (p-value = 0.015). Pressures observed in the Spillway–Deflector region and pressure rates of change decreased as well. Overall, the modifications resulted in improved hydraulic and fish passage conditions, which contributed to increased fish survival.
CitationDuncan J.P., Z. Deng, J.L. Arnold, T. Fu, B.A. Trumbo, T.J. Carlson, and D. Zhou. 2018. "Physical and Ecological Evaluation of a Fish-Friendly Surface Spillway." Ecological Engineering 110. PNNL-SA-126408. doi:10.1016/j.ecoleng.2017.10.012
A Hydropower Biological Evaluation Toolset (HBET) for Characterizing Hydraulic Conditions and Impacts of Hydro-Structures on Fish
AbstractCurrently, approximately 16% of the world’s electricity and over 80% of the world’s renewable electricity is generated from hydropower resources, and there is potential for development of a significant amount of new hydropower capacity. However, in practice, realizing all the potential hydropower resource is limited by various factors, including environmental effects and related mitigation requirements. That is why hydropower regulatory requirements frequently call for targets to be met regarding fish injury and mortality rates. Hydropower Biological Evaluation Toolset (HBET), an integrated suite of software tools, is designed to characterize hydraulic conditions of hydropower structures and provide quantitative estimates of fish injury and mortality rates due to various physical stressors including strike, pressure, and shear. HBET enables users to design new studies, analyze data, perform statistical analyses, and evaluate biological responses. In this paper, we discuss the features of the HBET software and describe a case study that illustrates its functionalities. HBET can be used by turbine manufacturers, hydropower operators, and regulators to design and operate hydropower systems that minimize ecological impacts in a cost-effective manner.
CitationHou H., Z. Deng, J.J. Martinez, T. Fu, J.P. Duncan, G.E. Johnson, and J. Lu, et al. 2018. "A Hydropower Biological Evaluation Toolset (HBET) for Characterizing Hydraulic Conditions and Impacts of Hydro-Structures on Fish." Energies 11, no. 4:990. PNNL-SA-124812. doi:10.3390/en11040990
Three-dimensional migration behavior of juvenile salmonids in reservoirs and near dams
AbstractTo acquire 3-D tracking data on juvenile salmonids, Juvenile Salmon Acoustic Telemetry System (JSATS) cabled hydrophone arrays were deployed in the forebays of two dams on the Snake River and at a mid-reach reservoir between the dams. The depth distributions of fish were estimated by statistical analyses performed on large 3-D tracking data sets from ~33,500 individual acoustic tagged yearling and subyearling Chinook salmon and juvenile steelhead at the two dams in 2012 and subyearling Chinook salmon at the two dams and the mid-reach reservoir in 2013. This research investigated the correlation between vertical migration behavior and passage routes. The depth distributions of fish within the forebays of the dams were significantly different from fish passing the mid-reach reservoir. Fish residing deeper in the forebay tended to pass the dam using deeper powerhouse routes. This difference in depth distributions indicated that the depth distribution of fish at the mid-reach reservoir was not related to behaviors of fish passing through certain routes of the adjacent dams. For fish that were detected deeper than 17.5 m in the forebays, the probability of powerhouse passage (i.e., turbine) increased significantly. Another important finding was the variation in depth distributions during dam passage associated with the diel period, especially the crepuscular periods.
CitationLi X., Z. Deng, T. Fu, R.S. Brown, J.J. Martinez, G.A. Mcmichael, and B.A. Trumbo, et al. 2018. "Three-dimensional migration behavior of juvenile salmonids in reservoirs and near dams." Scientific Reports 8. PNWD-SA-10471. doi:10.1038/s41598-018-19208-1
PNNL Launches Marine Renewable Energy Database
Tethys Engineering addresses industry’s technical and engineering challenges
Marine renewable energy (MRE) has the potential to provide 90 gigawatts of power in the United States through waves and tidal and ocean currents.
To harness the ocean’s energy, the MRE industry needs to understand how to address technical and engineering challenges such as efficient power takeoff, device survivability, and grid integration.
PNNL developed Tethys Engineering in September 2019 to allow sharing resources around the deployment of devices in corrosive, high-energy marine environments. The recently launched Tethys Engineering online database includes collected and curated documents surrounding the technical and engineering development of MRE devices. Users can search and filter results to intuitively identify information relevant to developers, researchers, and regulators.
Tethys Engineering includes more than 3,000 journal articles, conference papers, reports, and presentations related to wave, current, salinity gradient, and ocean thermal energy conversion technologies. The database contains information from around the world.
The Tethys Engineering database was created as a companion to the already established Tethys website, which focuses on the environmental effects of the MRE industry.
Understanding the Grid Value Proposition of Marine Energy: A Literature Review
In 2018, the US Department of Energy’s Water Power Technologies Office Marine Hydrokinetics Program directed two national laboratories, Pacific Northwest National Laboratory and National Renewable Energy Laboratory, to investigate the potential of marine renewable resources to contribute the U.S. electric system. Due to the innovative nature of marine renewable energy and the transformation of the US electric system resource mix, there is a lack of insight about the future potential role and grid value proposition of marine energy.
An initial step in this technical project is to review available literature to inform and help characterize the portfolio of potential marine energy resource contributions. This literature review summarizes the energy fundamentals of marine resources; the performance and operational characteristics of energy conversion devices; grid opportunities and integration challenges most applicable to marine energy; storage coupling to achieve grid opportunities; and offshore wind energy competition and collaboration. It provides the context and the state of knowledge in which the grid value proposition of marine energy should be further researched and explored.
Notable findings from the review include the following:
- Very little work has been conducted to connect the grid and fundamental marine energy development. Few technical papers attempt to demonstrate grid value from marine energy or, conversely, illustrate how grid applications may have an effect on device size and scale, convergence of device types, and location of marine energy technologies. Those that have done so relied on numerous estimations and assumptions and target very specific potential benefits.
- Aggregation of tidal generation for baseload—the concept of distributing tidal generators to accomplish complementary phase shifts in generation that, when summed, would provide relatively stable power—faces challenges from a cost perspective. One study evaluated three geographically separate, complementary locations off the Scottish coast. The study concluded that aggregate power generated from sites with varying resources is sensitive to the characteristics of the individual sites and some irregularity should be expected in aggregate power output due to natural variation in successive tides. Ultimately, the study suggests that using complementary sites and limiting the capacity of the turbines, particularly during neap tides, could create baseload power, or a constant power output; but the research team expressed concerns regarding whether such a deployment would be cost effective. Decreasing the turbines’ rated capacity and therefore not capturing the resource to its fullest extent would cause economic losses.
- Tidal energy-generating profiles may be well matched for storage. Energy storage is a fast-growing resource in the energy industry. It can provide value in a multitude of grid situations, including supporting marine energy technologies. One report suggests that because tides are predictable, tidal technologies are ideal for pairing with energy storage to create a steady output of power. In fact, Nova Innovation recently integrated a Tesla battery storage system with the Shetland Tidal Array in Scotland and expanded the generating capacity and enabled dispatchability at the site.
- There is a potential match between resource peak and electric demand. When considering a seasonally peaking resource, like wave energy, there is an opportunity for the generation patterns to be well matched with energy demand. For example, one study noted that British Columbia’s energy consumption peaks in the winter when the available wave resource is also at its strongest; this same characteristic is true along the rest of North America’s Pacific Northwest coast.
- Co-location may deliver grid benefits. A study evaluating a portion of the North Sea showed that there could be significant benefits to co-locating wave devices and offshore wind turbines. When wind and waves are negatively correlated, this decreases variability and can help mitigate grid integration concerns that are sometimes associated with variable generation. Being proactive in the siting process and performing quantitative spatial planning can avoid potential conflicts between sea uses, while harnessing the most useful energy.
- The availability and cost of land was used in utility decision-making for resource selection and resulted in a portfolio selection that included marine energy development. In a 2017 Integrated Resource Plan for the Caribbean Utilities Company (the public electric utility for Grand Cayman in the Grand Cayman Islands), a contractor evaluated land use associated with different generation technologies and found a significant advantage to using marine energy, specifically ocean thermal energy conversion (OTEC). Accordingly, and despite a higher capital cost for OTEC relative to other resource options, the resource plan containing OTEC was among the two recommended portfolios. In the portfolio, OTEC resources replaced onshore solar development, which requires a relatively high land commitment proportional to total generation, as well as natural gas-fired backup generation and battery storage. Although OTEC is not considered in this report, connections can be drawn to the technology, and research from that field is applicable to other marine energy resources in particular instances.
As the marine energy industry grows, there is a corresponding increase in the body of literature about both the potential value of harnessing marine resources as well as the requisite technical work to integrate the resource into the grid. Due to the unique aspects of marine energy resources, especially their offshore location, volume, and predictability, there are many reasons to consider marine energy a viable potential renewable resource in the future electric system.
Understanding the Grid Value Proposition of Marine Energy: An Analytical Approach
The US Department of Energy’s Water Power Technologies Office (WPTO) has tasked two national laboratories, Pacific Northwest National Laboratory (PNNL) and National Renewable Energy Laboratory (NREL), to develop an understanding of the grid value proposition for marine renewable energy (MRE): how harnessing the energy of waves, tides, and ocean currents could be a meaningful and competitive source of renewable energy in the future grid.
This work will provide insights to the conditions under which MRE technologies offer unique benefits for the electricity system. PNNL and NREL will conduct a project to comprehensively review the grid value for marine renewable energy development at scale on an intermediate- to long-term horizon. The project will dovetail with nationally-accelerating valuation efforts to characterize and quantify specific services from energy resources and assess the value of those services over time. It will capitalize on the emerging concept of locational value, especially for distributed energy resources (DER), referencing adopted frameworks and related laboratory analysis. And it will take advantage of laboratory expertise in a variety of disciplines – ocean physics, mechanical and electrical engineering, energy economics – chained together in order to ensure that benefits and services assessed are realistic for MRE technologies and ocean energy resources.
The purpose of the immediate analytical approach is to outline the landscape of MRE attributes and their potential value and, at a high-level, discuss methods to quantify these values. For purposes of this investigation, the words grid value should be broadly construed. The term is meant to include, but not be limited to, provision of a defined grid service, measurable benefit to grid performance, avoided costs to system investments or operations, revenue capture, and contribution to desired grid qualities (e.g. reliability or low carbon intensity). Value can also accrue to a range of entities.
The authors intend to consider use cases and system benefits where MRE may have a competitive or unique role; and where there is a distinct and measurable value additional to energy production. To do this, the authors look beyond the typical values of energy production (a payment of cents per kilowatt-hour produced) and instead to “grid services,” those services required for the grid to operate and deliver energy to customers (i.e. unit scheduling and dispatch, reactive power and voltage control, and frequency control). Certain grid services are captured in the traditional suite of ancillary services that may be directly compensated in an organized market, and as a result many of these benefits already have highly competitive contributing generators or other electricity system assets. Therefore, in this initial exercise of considering competitive and unique benefits, the authors are less concerned with the energy (or grid service) production itself but the timing, the location, or the system condition that form measurable and distinct value.