A recently completed inventory of Canadian small hydro sites identified over 5500 sites with a technically feasible potential of about 11,000 MW but only about 15 per cent of this total would be economically feasible under currently socio-economic conditions and at the current state-of the –art. If capital cost can be reduced by 10 to 15 per cent, which should be achievable though further technological improvements, a further 2000 MW of economically exploitable small hydro capacity will be available. A good number of these will be small hydro projects. In a deregulated electrical generation environment, hydro power offer the prospect of earning longer-term, sustainable return. A comparison of the yield factors of various types of Energy plant suggests that hydro power remains the most valuable form of energy since it provided the highest quantity of energy produced over its lifetime as compared to the energy required for manufacture, operation and disposal including secondary energy.

Rehabilitation of historical plants is also a cost effective strategy. Quite apart from new plant, many stations are now at an age where maintenance and refurbishment are critical. Now, owing to rapid developments in computerized hydraulic design, it is possible not only to restore older plants but actually to improve their performance.

Small Hydro Technology Development in Canada

It is in the replacement of expensive diesel generation in remote, off-grid communities that small hydropower generation has its greatest benefit in cost to Canada. Public electric utilities in Canada are required to provide electric service to isolated communities so that such utilities in several of the provinces are encouraging private development of abandoned power plants and at existing dams as well as new developments of small hydro to substitute for diesel power in remote communities.

The objective of the Canadian Small Hydro Technology Development Program (2) is to promote the development of appropriate technology to enable a greater ranger of small-scale and low-head hydro resources to be exploited economically. This programme responds to the needs of the Canadian small hydro industry and links the expertise in industry, universities and other relevant government programmes. The primary effort is now concentrated on developing tools and techniques to reduce equipment and construction costs. The programme has already yielded a number of worthwhile technical innovations, several of which are outlined hereunder.

A micro-hydro, stand-alone induction generator system has been successfully developed using low-cost electronic controls. Two systems were produced: one provides DC power to charge batteries and the other provides standard AC power for general use. The frequency control is precise, allowing use of electronic equipment on the circuit. Both systems are small with capacities up to 10kW intended for use by isolated homesteads. Several AC systems have been constructed using centrifugal pumps as turbines with outputs up to 8000 watts, three phases. These systems have shown distinct advantages for micro hydro installations, such as: lower costs because of the induction motors, more rugged construction and general availability; greatly reduced short-circuit energy; ability to withstand 100 per cent over speed; and good sinusoidal power wave form with low harmonics and high efficiency in the range of 86-96 per cent.

The Development Programme co-sponsored the setting up of a modern laboratory at Laval University, Quebec City for testing small hydro turbines developed by industry and for carrying out research on turbines. It is the only independent turbine testing laboratory in Canada. A 120 kW tubular (S-type) hydraulic turbine, developed during the period 1986-91 by Dr. Netsch at Laval University with micro-processor control for head up to 30m and capacities less than 1MW, is being tested by the Laboratory.

A centre of expertise for computer modeling and simulation of flow through hydraulic turbines has been established by the University of Montreal with participation of CANMET, Concordia University, McGill University, Hydro Quebec, General Electric Canada and GEC Alsthom. This Centre de recherche au calcul applique (CERCA) is focusing on the development of advanced computer simulation models for turbine flow analysis which could reduce the need for costly physical model testing trials. CERCA is currently assisting CANMET in the development of two simulation models for analyzing innovative small hydro turbines. The resulting technologies will subsequently be transferred to the small hydro industry. Simulation models developed by CERCA can be validated at the testing facility at Laval University.