EPRI, NYPA testing concrete crawler robot
To improve on manual inspection of concrete structures, the Electric Power Research Institute and New York Power Authority are testing use of an autonomous concrete crawler robot.
The crawler uses a commercially available robotic platform that can carry more than 40 pounds of equipment to climb the surface of structures. The crawler can negotiate concave, convex or overhanging vertical structures. Its on-board systems include simultaneous localization and mapping technology and nondestructive evaluation (NDE) instrumentation that are used to conduct automated, high-precision inspections and to capture computer-encoded data and images.
The concrete crawler can be used to inspect such structures as dams, cooling towers and transmission tower pedestals. It eliminates the need to use scaffolding or rappelling for routine structural evaluations, avoiding the associated setup challenges, time requirements, costs and safety hazards.
Proof-of-concept testing of the crawler was completed at NYPA's Niagara hydro facility in July, and EPRI is performing follow-on enhancements to the navigation system. The results also will be used to define the crawler's NDE functionalities and power supply, data collection and processing and communications capabilities.
A first-generation prototype is scheduled to be built and evaluated in 2014, with further refinements and field tests leading to the development of specifications for a commercial inspection robot.
NMFS uses Alden data to determine salmon "take"
The National Marine Fisheries Service has used Alden's survival estimating tool to develop a population model for incidental "take" of endangered salmon at hydroelectric projects.
Atlantic salmon smolts and kelts may be subject to mortality at hydro facilities due to injuries sustained during passage through turbines and fish bypasses or over spillways, Alden says. Indirect mortality may result from increased predation rates or reduced fitness associated with the stress of downstream passage and migration delays. Cumulative effects from passage at multiple projects may also lead to increased mortality and reduced fitness during the in-river migration and after fish reach the estuary and marine environment.
NMFS developed an Atlantic salmon population model that estimates survival for smolts and kelts passing downstream. To obtain this information, NMFS contracted Alden to estimate downstream passage survival at 15 hydroelectric projects on Maine's Penobscot River and its tributaries. Most of the projects studied have upstream passage facilities for anadromous species, as well as downstream bypasses for juvenile and adult outmigrants.
These desktop survival estimates focus on direct and indirect mortality attributable to passage at a dam and exposure to multiple dam passage, Alden says. An established turbine blade strike probability and mortality model was used to estimate direct survival of fish passing through turbines at each project. Survival rates for fish that pass downstream over spillways or through fish bypass facilities was estimated based on existing site-specific data or from studies conducted at other hydro projects with similar species.
This survival analysis provided data that would have been expensive and difficult to obtain with field studies, Alden says. Typically, such studies conducted in the field only evaluate one or two turbines operating at one or two gate settings.
Study examines effects of hydro outside the river system
Study results indicate hydro projects on irrigation systems in the Hood River watershed in Oregon provide valuable benefits, such as revenue to fund water conservation and river restoration projects.
The study was sponsored by the Bonneville Environmental Foundation and Energy Trust of Oregon and conducted by Farmer's Conservation Alliance. BEF and ETO are interested in developing low-impact hydro projects, particularly those that could be incorporated into a water distribution system. FCA seeks to develop resource solutions for rural communities.
The study examines the cumulative effects of small-scale hydropower generation by two irrigation districts over the past 30 years: Farmers Irrigation District and Middle Fork Irrigation District. FCA reports positive impacts on fish "realized through the generation of nearly $90 million in revenue that funded infrastructure improvements leading to increased summer stream flows, installation of fish screens, removal of passage barriers, and increased collaboration within the watershed community." In Oregon, there are 55,000 to 70,000 diversions.
- The report is free at http://farmerscreen.org/cms/wp-content/uploads/2013/09/FCA-Hydro-Case-Study-2013.pdf.