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ENGINEERING A WIDE AREA OF INNOVATIONS FOR GREEN POWER GENERATION Nowadays engineers working in the small-hydropower (SHP) field keep on developing techniques specific to small hydropower, in order to face up to the following challenges:

• increase environmental integration • decrease cost • maximize electricity production

Hydro-mechanical engineering: site-specific small hydropower plant


he main objective of hydro-mechanical engineers is to develop turbines that use water resource optimally, by designing turbines that are specific to the sites. Therefore the R&D on SHP has focused on very-lowhead and low-head turbines, as these sites make up the important remaining potential in developed and emerging countries. Notably, pico and micro hydro turbines are developed to meet the demand for rural electrification and small isolated network.

Cavitation on a blade

Francis runner

CFD (Computational Fluid Dynamics)

Optimal use of the water resources implies an improvement in the hydraulic design that aims not only at higher efficiency, but also lower costs, a high reliability and an optimal environmental integration (fish-friendly turbines). Such objectives are achieved through CFD (Computational Fluid Dynamics) calculation, systemisation and laboratory development, and specific small hydro products are to be designed, rather than simply scaling down larger turbines. Moreover the development of solutions for the equipment of existing infrastructures (such as irrigation channels, drinking water and sewage networks), by using for example new materials to reduce cost, is another challenge the hydro-mechanical engineers have to face.

Axial turbine set on a test bench

Pelton runner 8-blade turbine for low-head site


8-blade turbine for low-head site

for the best compromise between technology, economy and environment


Dam, intake and

t present, most efforts concerning civil engineering aim at standardizing design and technology, so as to reach an optimal integration of an SHP plant with the local environment while minimizing costs.

settling basin

Such objectives are reached by setting guidelines based on the latest design technology, new materials and best practice examples. The development in civil engineering is continuously expanding and it is essential to integrate this development into the basic design technology through the whole chain of the power plant design and construction. Indeed the global objective is to reach an optimal solution and a good environmental integration for every specific hydropower plant, both for new projects and restoration of old plants. Overflow dam Control & monitoring

Electrical engineering: for an easy and low-cost integration to the grid


vailable solutions for SHP electrical engineering range from generators, grid connection over electric drives to the control and management of the whole power plant. New generator designs such as high pole synchronous generators with permanent magnet excitation have been introduced to the SHP market. Designed for direct grid connection or in combination with a frequency converter for variable speed operation, such generators allow to avoid speed increasers and make very compact submersible turbine designs possible. Moreover environment-friendly transformers such as oil-free cast resin ones can also be found on the market. Current digital control systems offer site specific optimization methods in order to adapt the overall control to any hydrological or other condition. This can include identification of the optimum runner and guide vane set points, the optimized water level control, the improved operation of the trash rack cleaner and the automatic identification of any malfunction. Generator

State of the art industrial automation components and excellent communication features ensure that an operator can identify the status of the plant at any time and anywhere, using computers, PDAs, cell phones or just a simple telephone and allow to respond remotely on problems, where applicable. New concepts such as scheduled production, prediction of the energy output and condition monitoring are currently under development also for SHP in order to improve the grid integration, to increase reliability and to reduce the operation & maintenance cost.


Civil engineering:


for protecting aquatic ecology

T Fish bypass system equipped with brushes

Fish bypass system

he significant increase in knowledge concerning the biological mechanism in rivers has consequently initiated the development of “environmental engineering”, focussing on minimizing and mitigation of negative environmental impact. Well-known examples are fish-bypass systems, environmental flow or river restructuring. The close cooperation with ecologists has led to excellent compromises between environmental targets and economic and technical restrictions.

Such engineering is in continuous evolution. For example, nowadays, it has been found that contrary to a constant amount of environmental flow, the variability according to natural discharge conditions brings about ecological benefits at lower costs. Moreover, regarding fish-bypass systems, new technically optimised installations such as the vertical slot pass or the Denil-pass guarantee the highest fish acceptance while reducing the amount of bypass operation flow. SHP-projects have often other functions besides the production of electricity. The removal of the trash picked up at the screen at an SHP plant guarantees the cleaning of the river. The increase of flood protection or the adaptation as recreation area are items of public interest and can be achieved by interdisciplinary and sustainable planning. Finally, environmental engineering can include the management within the entire implementation process and the participation of involved people is a typical topic.


his leaflet has been prepared within the Thematic Network on Small Hydropower (TNSHP) Project. The Thematic Network on Small Hydropower (TNSHP) is a European Commission - DG TREN (Transport & Energy) and Swiss Government - funded project in the framework of the EU’s FP5 (Fifth Framework Programme for Research, Technological Development and Demonstration - RD &D). ESHA, the European Small Hydropower Association, is the European co-ordinator of this project which includes ten additional partners: ADEME (France), EPFL-LCH (Switzerland), ISET (Germany), IT Power (United Kingdom), KÖ (Austria), Lithuanian Hydropower Association (Lithuania), MHyLab (Switzerland), SCPTH (France), SERO (Sweden) and Studio Frosio (Italy). This leaflet is built on the RD&D Strategy document prepared by the engineering group of the TNSHP, coordinated by MHyLab, which presents the priorities for SHP short-term research. If you would like to know more about this SHP RD&D Strategy document, please contact ESHA or MHyLab.

EUROPEAN SMALL HYDROPOWER ASSOCIATION Renewable Energy House 63-65 Rue d’Arlon B-1040 Brussels • Belgium T: +32 2 546 1945 F: +32 2 546 1947 E: • I:

Basin created by a weir

MHyLab - MINI HYDRAULICS LABORATORY CH-1354 Montcherand Switzerland T: + 41 24 442 87 87 F: + 41 24 441 36 54 E: I:

Illustration sources: MHyLab, VATECH, Elmotech, Ingegneri Maggia SA, Commune de Savièse (CH), ISET, Studio Frosio, SERO, EPFL-LCH, Walcher, Sasso s.r.l.

Environmental engineering:

Design : ACG Brussels

Fish bypass system


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