29-06-2012, 01:27 PM
Hydroelectricity
ABSTRACT
Hydroelectricity is an important renewable resource. In particular, small “run-of-river” hydroelectricity has abundant potential considering the mountainous geography and the wet climate. Freshwater and steep terrain is abundant. Small hydro development
began in the early 1990’s and has grown slowly to produce about 5% of the province’s energy supply today. There are over 36 operating run-of-river projects in BC with an average power capacity of 10-20MW, and are typically taking 5 to 15 years from concept to operations, with an operational life of 40 years.
Run-of-river hydro projects do not use the flooding of land as a reservoir of potential energy production. Instead, they rely on the natural flow of the river to provide power to the downstream turbines at the powerhouse. A portion of the river flow is diverted out of the river through a pipe (penstock) and run downhill to the powerhouse. The diverted water is returned to the river downstream of the powerhouse.
As with any resource development, there are potential impacts to environmental and social values. A runoff-river project in BC requires approximately 50 permits for a variety of activities, including an environmental assessment of potential effects to fish, wildlife, other resource uses, recreation, First Nations interests, and other ecological or social values. Public economic benefits are clear: a 10 MW runoff-river project built in 2003 will pay about $20 million in direct taxes, fees, water rentals, and community benefits over the life of the project.
Maintain Flows and Water Quality for Ecological Integrity:
The aquatic impacts from a small hydro project are due largely to changing the flows and possibly the water quality in the diversion reach of the river. The amount of water that is diverted away from the river is determined through a complex analysis of the flow requirements in the river to maintain the ecological values of the system over different periods in the year. A complete site-specific understanding of the river ecology is required with specific attention to the fish distribution and how different species use different parts of the river at different times of year.
Identifying the in stream flow requirements over these periods is fundamental to preserving the existing populations. Amphibians and aquatic invertebrates are also considered in examining potential impacts from flow changes. One full year of biological data collection and continuous hydrometric data is typically required to establish baseline hydrological conditions. This hydrology and ecology data will also provide the information needed to establish how quickly flows can be changed – “ramping rate” – to avoid harmful effects such as stranding fish when water is suddenly diverted. An appropriate ramping rate (in m3/s) is established so that changing water flows are gradual enough to reduce risk of impact. The physical characteristics of the river channel are required to understand how changing flows may change the geomorphology and sediment transport (and hence the habitat) of the river.
Sensitive Design of the Linear Components:
There are typically three main linear components to a small hydro development: the access road, the penstock and the transmission line. To be most cost-effective, the linear components are designed to be as short as possible considering terrain constraints. For various land use and environmental reasons, these components should be designed to avoid valuable areas. To examine feasible route options, identification of sensitive areas is essential. Areas that may be protected include wetlands, sites of cultural value (archaeological or historical interest), old forests or popular flyways for birds (for transmission lines).
Mitigating the impacts of overhead transmission lines on birds involves careful consideration of the location and visibility of the line so bird strikes and electrocutions are avoided. The detailed design of the transmission structures should consider options to enhance visibility of the line in sensitive areas and prevent electrocution of larger birds that may be at highest risk. Often, the best practice is to design the linear components along areas of previous disturbance such as existing roads. In certain cases, placing the transmission line or penstock underground is an option to avoid fish, wildlife or visual impacts.
Public Participation:
A project-specific public participation plan should be developed and implemented at the outset of project definition to provide an appropriate level of public involvement in the project design and impact assessment.
Manage Impacts on Other Land and Resource Uses
Small hydro projects need to be designed to ensure that other land and resource users can continue to operate. In BC, other land use types include forestry, agriculture, fisheries, recreation, tourism, parks and other designated significant areas. Early identification of these land use constraints and discussions with other land users can resolve possible conflicts and may identify areas where there can be mutual benefits. For example, many hydro projects will use old forestry roads that require maintenance for future use. The road upgrade and maintenance provided for the hydro project construction can benefit the future forestry activities in the area. The regulation of water flows might also improve recreational use of the river for kayakers.
As a result of the impact assessment and stakeholder consultations, government approvals and permits for small hydro projects typically contain many commitments to implement environmental mitigation measures and management plans. Measures to protect fish, wildlife, cultural sites, and recreational use are normally included. An independent environmental monitor is required to observe the implementation of these measures to ensure compliance. During the construction phase, the monitor advises on the use
Of low impact construction methods in sensitive areas. These methods are usually coordinated with the
Timing of sensitive periods for fish and wildlife to minimize risk of impact. A primary focus is the management of water flows and water quality during the construction phase.
Monitoring during the operational phase is a longer term study to verify the accuracy of impact predictions, and inform alternatives in the event of non-compliance. In BC, this compliance and response monitoring typically focuses on compliance with flow constraints (in stream flow requirements) and ongoing data collection for fish populations and fish habitat indicators (e.g., water quality and benthic Invertebrates) to monitor changes during operations. This data collection may occur over the first five totem years of project operations. For meaningful comparisons of operational data, solid baseline data is required prior to project construction to enable a reliable and statistically defensible before-after / control impact study. This is an important consideration during the preconstruction data collection planning, and also if an adaptive management plan is contemplated. Compliance monitoring for construction and operational implementation of mitigation and management measures is essential for project proponents to be accountable, and for future projects to learn and improve development planning.
CONCLUSION
The small hydroelectricity industry in BC presents tremendous opportunities for renewable energy generation, social and economic benefits for First Nations, and replacement of diesel electricity in remote communities. Sustainable development of this resource requires implementation of environmentally and socially responsible approaches to design, construction and operations. Seven general best practices have been presented. These practices have emerged over two decades of project development in BC, and can be used as a model for other jurisdictions with small hydro potential.
ABSTRACT
Hydroelectricity is an important renewable resource. In particular, small “run-of-river” hydroelectricity has abundant potential considering the mountainous geography and the wet climate. Freshwater and steep terrain is abundant. Small hydro development
began in the early 1990’s and has grown slowly to produce about 5% of the province’s energy supply today. There are over 36 operating run-of-river projects in BC with an average power capacity of 10-20MW, and are typically taking 5 to 15 years from concept to operations, with an operational life of 40 years.
Run-of-river hydro projects do not use the flooding of land as a reservoir of potential energy production. Instead, they rely on the natural flow of the river to provide power to the downstream turbines at the powerhouse. A portion of the river flow is diverted out of the river through a pipe (penstock) and run downhill to the powerhouse. The diverted water is returned to the river downstream of the powerhouse.
As with any resource development, there are potential impacts to environmental and social values. A runoff-river project in BC requires approximately 50 permits for a variety of activities, including an environmental assessment of potential effects to fish, wildlife, other resource uses, recreation, First Nations interests, and other ecological or social values. Public economic benefits are clear: a 10 MW runoff-river project built in 2003 will pay about $20 million in direct taxes, fees, water rentals, and community benefits over the life of the project.
Maintain Flows and Water Quality for Ecological Integrity:
The aquatic impacts from a small hydro project are due largely to changing the flows and possibly the water quality in the diversion reach of the river. The amount of water that is diverted away from the river is determined through a complex analysis of the flow requirements in the river to maintain the ecological values of the system over different periods in the year. A complete site-specific understanding of the river ecology is required with specific attention to the fish distribution and how different species use different parts of the river at different times of year.
Identifying the in stream flow requirements over these periods is fundamental to preserving the existing populations. Amphibians and aquatic invertebrates are also considered in examining potential impacts from flow changes. One full year of biological data collection and continuous hydrometric data is typically required to establish baseline hydrological conditions. This hydrology and ecology data will also provide the information needed to establish how quickly flows can be changed – “ramping rate” – to avoid harmful effects such as stranding fish when water is suddenly diverted. An appropriate ramping rate (in m3/s) is established so that changing water flows are gradual enough to reduce risk of impact. The physical characteristics of the river channel are required to understand how changing flows may change the geomorphology and sediment transport (and hence the habitat) of the river.
Sensitive Design of the Linear Components:
There are typically three main linear components to a small hydro development: the access road, the penstock and the transmission line. To be most cost-effective, the linear components are designed to be as short as possible considering terrain constraints. For various land use and environmental reasons, these components should be designed to avoid valuable areas. To examine feasible route options, identification of sensitive areas is essential. Areas that may be protected include wetlands, sites of cultural value (archaeological or historical interest), old forests or popular flyways for birds (for transmission lines).
Mitigating the impacts of overhead transmission lines on birds involves careful consideration of the location and visibility of the line so bird strikes and electrocutions are avoided. The detailed design of the transmission structures should consider options to enhance visibility of the line in sensitive areas and prevent electrocution of larger birds that may be at highest risk. Often, the best practice is to design the linear components along areas of previous disturbance such as existing roads. In certain cases, placing the transmission line or penstock underground is an option to avoid fish, wildlife or visual impacts.
Public Participation:
A project-specific public participation plan should be developed and implemented at the outset of project definition to provide an appropriate level of public involvement in the project design and impact assessment.
Manage Impacts on Other Land and Resource Uses
Small hydro projects need to be designed to ensure that other land and resource users can continue to operate. In BC, other land use types include forestry, agriculture, fisheries, recreation, tourism, parks and other designated significant areas. Early identification of these land use constraints and discussions with other land users can resolve possible conflicts and may identify areas where there can be mutual benefits. For example, many hydro projects will use old forestry roads that require maintenance for future use. The road upgrade and maintenance provided for the hydro project construction can benefit the future forestry activities in the area. The regulation of water flows might also improve recreational use of the river for kayakers.
As a result of the impact assessment and stakeholder consultations, government approvals and permits for small hydro projects typically contain many commitments to implement environmental mitigation measures and management plans. Measures to protect fish, wildlife, cultural sites, and recreational use are normally included. An independent environmental monitor is required to observe the implementation of these measures to ensure compliance. During the construction phase, the monitor advises on the use
Of low impact construction methods in sensitive areas. These methods are usually coordinated with the
Timing of sensitive periods for fish and wildlife to minimize risk of impact. A primary focus is the management of water flows and water quality during the construction phase.
Monitoring during the operational phase is a longer term study to verify the accuracy of impact predictions, and inform alternatives in the event of non-compliance. In BC, this compliance and response monitoring typically focuses on compliance with flow constraints (in stream flow requirements) and ongoing data collection for fish populations and fish habitat indicators (e.g., water quality and benthic Invertebrates) to monitor changes during operations. This data collection may occur over the first five totem years of project operations. For meaningful comparisons of operational data, solid baseline data is required prior to project construction to enable a reliable and statistically defensible before-after / control impact study. This is an important consideration during the preconstruction data collection planning, and also if an adaptive management plan is contemplated. Compliance monitoring for construction and operational implementation of mitigation and management measures is essential for project proponents to be accountable, and for future projects to learn and improve development planning.
CONCLUSION
The small hydroelectricity industry in BC presents tremendous opportunities for renewable energy generation, social and economic benefits for First Nations, and replacement of diesel electricity in remote communities. Sustainable development of this resource requires implementation of environmentally and socially responsible approaches to design, construction and operations. Seven general best practices have been presented. These practices have emerged over two decades of project development in BC, and can be used as a model for other jurisdictions with small hydro potential.