EPRI studying hydro reservoirs and greenhouse gas emissions
EPRI is funding a two-year study to assess the importance of carbon cycling and greenhouse gas emissions from hydropower reservoirs and operations in the U.S., says Douglas A. Dixon, senior program manager with EPRI. Oak Ridge National Laboratory (ORNL) is performing the study.
The first year of the study is focusing on a literature review of peer-reviewed publications from 1990 to the present, to provide a synthesis of what is known. As part of this work, ORNL developed a literature database that is searchable four ways:
- – Site features, such as climate, development, and land cover;
– Measurements, such as frequency, surface flux, and ebullition;
– Modeling, such as surface flux, ebullition, and degassing releases; and
– Findings, such as net source/sink, gross emissions, and uncertainty estimate.
Once the literature review is complete, Dixon says ORNL will produce a report that offers a conceptual model of altered (net) carbon cycling through reservoirs. The model will explain both temporal and spatial variability in greenhouse gas emissions. The report also will address the gaps in science for assessment of reservoir carbon cycling. The report is expected to be available in mid-2009.
Dixon says the second year of the study will focus on a review of greenhouse gas monitoring protocols and recommendation of a protocol that is appropriate for hydro reservoirs in the U.S. A research plan will be developed to fill gaps in knowledge required to accurately understand the contribution hydro reservoirs in the U.S. make with regard to greenhouse gases, relative to other sources.
PGE studying flow control structure at Willamette Falls
Portland General Electric Company (PGE) in Portland, Ore., is conducting a multi-year study to evaluate how a new flow control structure will affect fish passage at the 16-MW Willamette Falls project. This flow control structure, built at the dam crest, is intended to provide a downstream passage route for anadromous fish in the Willamette River.
The Willamette Falls project has a large submerged rock formation in the river downstream of the dam. When flow is low, rocks at the base of the falls are exposed, potentially increasing mortality of fish passing over the falls.
PGE designed the flow control structure to guide downstream migrants over the falls at a location more conducive to safe downstream fish passage during low river flows. The flow control structure is a 200-foot-wide opening with three gates installed in place of the section of the dam at the apex of the falls. This opening focuses river flow through a natural channel below the gates and into a pool at the base of the falls.
Baseline Industrial Construction, Inc. of Portland, Ore., manufactured the flow control structure and completed installation in the fall of 2007.
Fish passage survival through the structure, required in the terms of the new Federal Energy Regulatory Commission (FERC) license for the project, is 97 percent direct survival. Before this, there was no fish passage survival standard at the falls.
The study plan, required to satisfy a settlement agreement filed with FERC as part of Willamette Falls’ relicensing effort, is intended to evaluate or assess:
- – Mortality and injury to spring chinook salmon and steelhead smolts and juvenile Pacific lamprey when passing through the flow control structure;
– The condition of downstream migrating steelhead kelts, adult salmonids classified as fallback, and adult Pacific lamprey at the flow control structure;
– Whether the flow control structure adversely affects adult salmonid attraction to the four entrances to the existing fish ladder; and
– Effects of operation of the flow control structure on water quality.
Normandeau Associates Inc. is assessing fish passage performance through the flow control structure. Other aspects of the study are being performed by PGE fishery biologists. To estimate direct effects of survival and associated injury on downstream migrants, PGE is conducting a balloon tag study using HI-Z Turb’N tags.
The study began in the spring of 2008. PGE will file interim reports with FERC summarizing the results of each year’s study and a final report after at least three years of study are completed. PGE plans to submit the final report by the end of 2010.
Reclamation performing research on mussel control
The U.S. Department of the Interior’s Bureau of Reclamation is spending about $1 million in 2009 to perform research related to control of zebra and quagga mussels in western waters, says Peter Soeth, public affairs specialist with Reclamation.
These freshwater mussels arrived in the U.S. from Europe in the 1980s. Zebra and quagga cause significant problems at hydro facilities because they enter the plant and attach to a hard surface, such as the inner surfaces of pipes, and quickly form dense mats. There they grow in size, reducing the effective cross section of intakes and pipes.
Reclamation has undertaken several projects to help guide its research and development activities with regard to prevention, monitoring, control, and environmental effects, Soeth says. Research being performed includes:
- – Improving microscopy techniques for detecting zebra and quagga mussel larvae in water samples;
– Applying the polymerase chain reaction method to detect mussel larvae in water samples;
– Using new real-time imaging technology to detect mussel larvae in water samples;
– Applying quantitative imaging to monitor fouling of inaccessible underwater structures;
– Identifying best practices for monitoring for early detection, maintenance scheduling, and tracking population dynamics;
– Assessing the ability to control mussels using Psuedomonas fluorescens bacteria;
– Evaluating the use of coatings to minimize fouling and/or improve cleaning of fouled structures;
– Identifying potential anti-fouling materials that can be used to retrofit existing structures;
– Evaluating the use of filters and ultraviolet light to control fouling;
– Assessing spray methods for cleaning fouled pipes and trashracks;
– Testing of plasma shock cleaning methods for underwater structures;
– Evaluating the use of filtration systems to exclude mussels from plant cooling water systems; and
– Determining long-term ecological effects of mussel infestations within and downstream of reservoirs.
Soeth says Reclamation also is working to develop a guidance document, “Zebra and Quagga Mussel Research Program Management Plan.” This document is expected to be released in early 2009.
Hydro-Québec assesses effectiveness of sound barrier
The sound barrier installed at the 48.3-MW Rivière-des-Prairies project keeps American shad away from the powerhouse, but the utility needs to install more transducers to provide better coverage. These are the primary findings of a two-year research effort intended to determine the effectiveness of the sound barrier and any modifications needed, says Jean Caumartin, environmental adviser with Hydro-Québec.
Adult American shad, an anadromous fish, spawn upstream of the powerhouse.Once they spawn, the adults must pass the dam at Rivière-des-Prairies to return to the ocean. To keep American shad from passing through the turbines, in 2002 Hydro-Québec began shutting down the powerhouse one hour each day and opening the two spillway gates closest to the powerhouse. This arrangement took place for three to four weeks every June.
However, this arrangement left 23 hours in the day for fish to accumulate in the forebay and potentially pass through the turbines. According to Caumartin, the utility needed a way to keep the fish away from the powerhouse and to deflect them toward the spillway. In 2006, Hydro-Québec installed the sound barrier.
The sound barrier consists of an amplifier to produce sound and seven transducers mounted on aluminum poles to emit the sound in the water. Sound is emitted in a semicircle in front of the powerhouse.
To determine the effectiveness of the sound barrier, in both 2007 and 2008, Hydro-Québec used a scanning sonar tool already installed at the project to “sweep” the area in front of the powerhouse. Using the image generated, personnel were able to estimate the number and location of fish and thus determine the effectiveness of the sound barrier.
Results showed that the sound barrier is effective in keeping fish away from the powerhouse. Based on the results, the utility now operates the powerhouse 24 hours a day. However, the utility determined that more transducers are needed to provide adequate coverage across all the powerhouse intakes. Hydro-Québec is now determining the number and location of the additional transducers, Caumartin says.