Tech Briefs

Report released: Case studies on the benefits of dam removal

Headwater Economics released a research paper, Dam Removal: Case Studies on the Fiscal, Economic, Social and Environmental Benefits of Dam Removal.

In this 36-page report, the authors say: “While some dams continue to serve useful purposes, others have outlived their original function. For these obsolete dams, the benefits to the public of removing them outweighs the costs. It is appropriate to evaluate individual dams to determine whether their ongoing costs and effects on rivers and people justifies the services they provide.”

The report describes the methods used to measure the benefits of dam removal when compared with costs. It also includes five case studies ranging from small former mill sites to large western hydropower dam.

The report indicates that, for the Elwha and Glines Canyon dams, for example, the estimated cost of removal was $324.7 million but the estimated benefits were $5.38 billion: $5.3 million annually from increased commercial fishing, $33 million in personal income associated with dam removal, $43.8 million from 500,000 more visitor days annually, and $5.3 billion of improved well-being for the American public.

Schneider Electric named Clean Energy Company of the Year

Schneider Electric has been named Clean Energy Company of the Year by the Northeast Clean Energy Council. The award recognizes Schneider Electric for its leadership and contributions to the region’s clean energy economy, unwavering commitment to provide innovative business models, connected technologies and solutions, and significant deployment of clean energy in the Northeast region, a press release says.

“We believe that access to energy is a fundamental, basic human right. At the same time, we are also convinced that the current way of managing, consuming and producing energy is unsustainable,” said Kevin Self, Senior Vice President, Strategy, Business Development and Government Affairs, Schneider Electric. “At Schneider Electric we are energy optimists – we believe the solution is possible by using the technologies of today to help our customers manage their energy better.”

Schneider Electric specializes in energy management and automation and has more than 160,000 employees.

Technology tip: Dealing with threaded fasteners

Many nuances are overlooked in the application of threaded fasteners. With large shafts, often the most critical component is fastener integrity. Great effort is given to tightening and measurement of the elongation to assure the proper pre-load. But too often the locking mechanism is ignored. Direct welding of either bolt or nut will relax that pretension and provide a stress riser that will be a source of fatigue failure. Using a block to engage a flat of a hex nut is generally the best way to prevent rotation.

Smaller fasteners with 12-point heads can be fitted with matching arcs having 12-point configuration that can be welded without compromising the pretension. Socket wrenches can be sectioned to provide such arcs, or carbon steel heavy wall tubes may be broached to provide that match. Spring-lock washers are generally not suitable for locking high-strength materials. Locktite is a proven material for limiting rotation of an installed male threaded fastener with a tapped installation. Vibration is the reason threaded fastener loosen, so every effort should be made to limit the amplitude and frequency of vibration the element will be subjected to. Where nuts are used, non-metallic locking elements such as nylon insert ESNA (elastic stop nut) lock nuts work well.

Where stainless steel components are joined – such as the cone of a Francis runner or the blades, housing or trunnions of a Kaplan unit – the fastener should have adequate strength and resist galling. Nitronic 60 stainless steel provides both high strength and galling resistance and can be used as a nut, male threaded fastener or both.

– By Thomas Spicher, Hydro YES

OpEx Corner: Improper rope technique causes fall, injury

A survey crew was inspecting rock anchors on a dam structure. Improper rope techniques were used while descending, resuting in a fall and injury to the employee.

Review and incorporate the corrective actions and recommendations related to this event into your own procedures in order to prevent a reoccurrence.

Visit the National Hydropower Assocation’s OpEx database at www.hydroexcellence.org to learn more and join more than 100 companies that are exchanging critical hydropower information in a secure environment.

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