Tech Notes

Axial turbine developed for use in pipe systems

Researchers at the Technical University in Trondheim, Norway, have developed an axial turbine that can be installed in pipe systems.

The original goal was to develop a cost-effective unit that can be used where “compensation” flows are released, says Dr. Torbjørn K. Nielsen, a professor at the university. Compensation flow is the required minimum flow downstream. This typically would mean situations with heads up to about 50 meters. However, researchers quickly determined that the new axial turbine unit would operate well at heads as high as 100 meters, Nielsen says.

This turbine is intended for use in pipe systems that have surplus pressure that must be reduced. Rather than installing a pressure-reducing valve or another arrangement, installing the turbine allows for electricity production. Nielsen says examples of potential sites for this new turbine are water supply systems and pipes in fish hatcheries.

The turbine consists of two runners that rotate counter to each other. Each runner has a separate generator. The flow enters the first unit, where it causes rotation that generates power. The flow then enters the second unit, causing rotation that adds mechanical power to the shaft. The water then leaves the unit and continues through the pipe.

A 40-kW version of this unit is being tested in a pipe that provides minimum flows for the Tevla River, in connection with the 50-MW Tevla pumped-storage project.

In 2009, the university plans to install a 400-kW unit in western Norway in an old water supply system. This unit will be equipped with wicket gates for load regulation.

The turbine is expected to be commercially available in 2010.

Testing to date indicates the turbine has an efficiency of about 85 percent. In addition, it operates quietly, which is important if it is to be used near populated areas, Nielsen says.

Brazil water, electric agencies cooperate on hydro studies

Brazil’s water and electricity regulatory agencies are working together to streamline hydraulic basin studies for hydroelectric projects.

To foster this technical and scientific cooperation, electricity regulator Agencia Nacional de Energia Eletrica (ANEEL) and water agency Agencia Nacional das Aguas (ANA) signed a five-year agreement. The agreement is intended to guarantee speedier joint action on hydrologic issues, studies of hydropower potential, and operation and inspection of hydroelectric developments, ANEEL said.

ANEEL said the agreement will give continuity to the agencies’ activities related to operation of the national hydrometeorological network, exchange of hydrological and geo-reference information, and establishment of an inventory of available hydraulic resources, the Reserva de Disponibilidade Hidrica (RDH).

The RDH is a necessary document for the solicitation procedure for a hydro project, ANEEL said. The agency said it is up to the developer of feasibility studies of a project to provide an RDH to agencies managing a hydro resource, ANA, or state institutions.

NEMA publishes standard for welding symbols

The National Electrical Manufacturers Association (NEMA) announces EW 4-2009, a standard that establishes graphic symbols for arc welding and cutting apparatus.

The 65-page standard provides users and manufacturers with a system for developing and using graphic symbols on their equipment. This system accommodates non-English speaking and functionally illiterate workers. Symbols identify controls, indicators, connection points, junctions, and processes.

EW 4-2009 contains 277 standardized symbols, including all the pertinent graphic symbols recognized by the International Electrotechnical Commission’s (IEC) TC 26 standard for electric welding. In some cases, a single function or keyword is represented by more than one acceptable symbol, such as the symbol for engine developed by the International Organization for Standardization (ISO), IEC, and the Society of Automotive Engineers.

— The standard can be downloaded for free or purchased for $114 on the website:

ICOLD Forum: Using Dams and the World’s Water

Groups in several countries have adapted the International Commission on Large Dams’ (ICOLD) booklet, Dams and the World’s Water. These adaptations have allowed the groups to circulate the booklet throughout their countries, furthering its reach.

Click to EnlargeFor example, the Brazilian Committee on Dams (CBDB) translated the booklet into Portuguese, with a printing of 3,000 copies. This booklet will be distributed to CBDB associates, colleges, research centers, and professional institutions related to dam engineering, says Miguel Soria, director of CBDB’s Regional Center of Parana. In addition, CBDB plans to make an electronic version of the booklet available on its website. “Our intention is to disseminate information widely on the decisive role dams play in providing support to our current social, economic, and environmental model,” Soria says.

In Iran, the Iranian Committee on Large Dams (IRCOLD) translated the booklet into Farsi, says Ghasem Nasr, chairman of IRCOLD’s Committee on Public Awareness and Education. The committee prepared 1,000 copies of the booklet for distribution throughout Iran. “We believe that this book can boost our society’s information level about dams and their role in sustainable development of water resources management,” Nasr says.

The British Dam Society purchased 4,000 copies of the English version of the booklet to distribute in Europe, says Andrew Pepper, technical secretary for the society. These booklets were distributed to the Institution of Civil Engineers (to provide to children visiting a large dam in France), Royal Geographic Society (to provide to members who are secondary school teachers), and Geographical Association (to distribute to teacher members and others at association events and conferences). Each booklet distributed contained an insert indicating it was provided by the British Dams Society “as part of their objective of promoting understanding of the importance of dams and reservoirs within the infrastructure of society,” Pepper says. In addition, the society offers a PDF version of the booklet in the Student Zone of its website.

Dams and the World’s Water is a 68-page booklet published by ICOLD. ICOLD says the goal of this book is to explain, in a non-technical format, how dams help to manage the world’s water.

— To learn more about ICOLD activities, contact Michel De Vivo, Secretary-General, ICOLD 151, Bd Haussman, Paris 75008 France; (33) 1-40426824; E-mail:

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