Tech Notes

ICOLD Forum: Themes setfor 23rd Congress in Brazil

The International Commission on Large Dams (ICOLD) announces the four themes — known as “questions” — that will be considered at its 23rd Congress, to be held May 2009, in Brasilia, Brazil.

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The questions are:

  • Question 88: Dams and hydropower. ICOLD seeks papers about the role of dams and reservoirs with regard to renewable energy and sustainable development, as well as objectives for multi-purpose reservoirs and design requirements for pumped-storage schemes.
  • Question 89: Management of siltation in existing and new reservoirs. The question includes assessment of the issues, innovative design and layout to manage siltation, experience at existing projects, efficiency and cost of desilting structures, and reservoir management techniques.
  • Question 90: Upgrading of existing dams. Topics to cover include upgrading to improve structural and hydraulic performance or to meet new regulatory, environmental, or operational demands; as well as engineering issues and design alternatives in dam raising and the economics of dam raising.
  • Question 91: Dam safety management. ICOLD seeks information about risk assessment methods and results, regulatory and economical issues, effects on operation of reservoirs, emergency plans and communication, and remote monitoring and control of dams.

Prospective authors should check with their national committees for deadlines and other rules. Contact information for national committees is available at Completed papers must be submitted to ICOLD’s Central Office by June 25, 2008.

Using satellite data inwater management decisions

Data from a pair of orbiting satellites can be used to make more informed regional water management decisions, say scientists from the U.S. National Aeronautics and Space Administration (NASA). These Gravity Recovery and Climate Experience (GRACE) satellites, launched by NASA in 2002, detect the gravitational pull of water. Consequently, the satellites can measure snow, ice, and water in surface bodies and in soils and aquifers.

Scientists from NASA and the University of California, Irvine, have used data collected by the satellites over the past five years to estimate seasonal water storage variations in more than 50 river basins.

In particular, the researchers noted sharp water decreases in Africa, along the Congo, Zambezi, and Nile river basins. Researchers found that, over a three-year period, water storage along the Congo River Basin has decreased by nearly twice the amount Africans consume annually, excluding irrigation. In vulnerable parts of Africa and Southeast Asia, increasing populations and standards of living place demands on water resources that are often unsustainable.

When properly used, NASA scientists say, data from GRACE could help people react to changing water patterns. For example, information about snow packs on mountains could help predict inflow into river basins. Matt Rodell, a hydrologist at the NASA Goddard Space Flight Center, said this is already happening in Lake Chad, at the intersection of Chad, Niger, Nigeria, and Cameroon. Scientists are using predictions based on GRACE data a month to three months in advance to determine the water that will be available to farmers in the region.

— For more information on the GRACE satellites, visit the Internet:

Software available forinvestigating potential sites

Natural Resources Canada (NRCan) offers free computer software for evaluating potential sites for hydroelectric development. The software, the Small Hydro Project Model of the RETScreen International Clean Energy Project Analysis Software, can be used to evaluate expected energy production, life-cycle costs, and greenhouse gas emission reductions of a proposed hydro facility.

The CANMET Energy Technology Centre — Varennes initially developed the software for NRCan in 1998. The software, which has been upgraded several times, runs on a Microsoft operating system. RETScreen Version 4 was released in June 2007. The software is available in 25 languages.

Using the software, a project developer completes:

  • An energy model to determine the amount of clean energy that can be delivered by a project;
  • Cost analysis to determine the life-cycle costs of a proposed development;
  • An optional greenhouse gas analysis to determine reductions generated by the project;
  • Financial summary to estimate cash flows from the project; and
  • An optional sensitivity and risk analysis to aid in seeking project financing.

Developers can use the information derived from these analyses to prepare feasibility studies, due diligence reports, and market studies.

The software has been used by more than 82,000 people in 213 countries.

Electricité de France (EDF) has used RETScreen software to investigate sites in Nicaragua, Madagascar, and Poland for potential development of small hydroelectric projects. The French utility also has used the software to investigate three sites in France for development of large projects.

— For more information or to download the software, visit

Superconductor generator to be installed in Germany

The 3.9-mw Hirschaid facility, currently undergoing rehabilitation, will contain the world’s first high-temperature superconductor hydropower generator. Utility E.ON Wasserkraft GmbH expects that using this generator will improve the economic return of the project due to a significant increase in electrical efficiency of the generator.

The 1.25-mw generator is based on high-temperature superconductor materials patented by Zenergy Power plc. The machine is expected to deliver efficiency levels greater than 98 percent. Converteam, formerly Alstom Power Conversion, will build the generator, using superconductive coils made by Zenergy’s German operation, Trithor GmbH.

Stirling, a Dutch company, is providing a maintenance-free cryogenerator for cooling the new generator.

Development and installation of the generator is expected to cost 3.44 million euros (US$4.37 million), of which the European Commission is providing 1.85 million euros (US$2.3 million).

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