Increased Hydrogeneration while Improving Environmental Conditions (2)

Project ID: 9650
Principal Investigator: Merlynn Bender
Research Topic: Improved Power Generation
Priority Area Assignments: 2012 (Climate Adaptation)
Funded Fiscal Years: 2012 and 2013
Keywords: low-impact hydropower, tdg, renewable energy

Research Question

The primary product of this research is contribution to a white paper that provides a simplified approach for the development of a total dissolved gas (TDG) assessment and prediction tool at hydropower dams. Currently, the TDG environmental soft constraint is causing lost power generation at existing dams. A comparison between a dam where TDG is a concern and a dam where TDG is not a concern will be compared to identify the range of criteria needed for the assessment tool.

Based on TDG criteria, this renewable-energy research will further prioritize additional low-impact hydrogeneration Bureau of Reclamation (Reclamation) projects that could potentially reduce global climate change impacts. Emphasis will be placed on renewable energy from pumped storage/wind integration and conversion of nonhydropower dams to generation facilities.

For example, large dams with shallow downstream tailwater results in TDG concerns due to fish residing at shallow depths. Gas bubble disease (GBD) increases in fish when fish are in shallow water (depth compensation). Ten percent compensation roughly occurs with each meter of depth. So, if 120 percent TDG exists, 110 percent would be the biological equivalent at 1 meter deep, 100 percent at 2 meters, etc. Therefore, tailwater depth at various tailwater flows is one important factor in selecting or ranking dam sites for hydropower addition while minimizing TDG concerns.

This research will identify which soft and hard constraints (variables) are most important for predicting TDG concerns and ranking dam sites for additional hydropower generation.

Need and Benefit

The economy needs stimulation from infrastructure projects including additional hydropower projects. Impacts of global climate change needs to be reduced and environmental conditions for aquatic biota need to be improved. There is a need to explore additional hydrogeneration capabilities as a way of improving riverine environmental conditions.

There is a research need to integrate the electrical, mechanical, fishery bypass, environmental, and operational constraints to achieve acceptable operational and structural changes to the system at existing and proposed hydropower facilities.

Often TDG is a major limiting factor at hydrogeneration facilities. Currently, no simple method exists for quantifying the TDG effects between hydrogeneration facilities due to varying conditions. This research will develop a method to quantify the TDG soft constraint. This methodology should allow further prioritization of low-impact hydropower improvements at existing dams.

The primary benefit of this research will be development for a tool for predicting, ranking, and targeting increased hydrogeneration at existing dams.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Independent Peer Review

The following documents were reviewed by qualified Bureau of Reclamation employees. The findings were determined to be achieved using valid means.

Predicting Total Dissolved Gas (TDG) for the Mid-Columbia River System (final, PDF, 1.4MB)
By Dr. Boualem Hadjerioua, Dr. Marcela Politano, Ms. Scott DeNeale, Merlynn D Bender and Mr. Alejandro Castro
Report completed on July 13, 2014

Total dissolved gas (TDG) supersaturation in waters released at hydropower dams can cause gas bubble trauma that can lead to fish mortality. A generalized TDG exchange methodology for predicting TDG levels downstream of hydropower facilities with similar structural properties as a function of a set of variables that affect TDG exchange; such as tailwater depth, spill discharge and pattern, project head, and entrainment of powerhouse releases was presented for Mid-Columbia Dams.

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Prediction of Total Dissolved Gas (TDG) at Columbia River Basin dams (interim, PDF, 517KB)
By Dr. Boualem Hadjerioua
Research Product completed on July 18, 2013

The network of dams in the Columbia River Basin (CRB) is managed for irrigation, power production, flood control, and navigation. Spilling water mostly occurs during high river flows for flood control and for fish passage. During release events, air is entrained in the spilled water which could elevate the levels of total dissolved gas (TDG) saturation at the dam tailwater and for several miles downstream. A generalized TDG exchange model is being developed for use in water regulation models.

Predicting Total Dissolved Gas (TDG) for the Mid-Columbia River System (final, PDF, 1.2MB)
By Merlynn Bender
Publication completed on September 30, 2014

This bulletin summarizes the research results and potential application to Reclamation's mission.

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Last Updated: 6/22/20