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RETScreen® Small Hydro Project Model
with a runner diameter of 0.8 m is calculated as 3.2 m³/s. As such, in RETScreen, mini hydro
plants are defined as plants with total design flows between 0.4 m³/s and 12.8 m³/s.
Selected classification
The user selects the project category from the 3 options in the drop-down list: "Micro," "Mini"
and "Small." The costing formulae used for assessing the costs of certain components,
particularly the civil works, are affected by the project category. This is due to larger projects
requiring more conservative designs due to higher associated risks, especially with respect to
flood conditions.
The same classification as the suggested classification (previous cell) should be selected except
under the special circumstances as described below. The user may override the recommended
project classification by selecting a different project category from the drop-down list. This can
be useful when conducting sensitivity analyses particularly when the design flow being
considered is close to the categorisation limits described above. Also, in certain circumstances it
may be desirable to classify the project differently (e.g. mini hydro projects where high flood
risks exist and/or complicated project designs are required could warrant categorising the other
project components as "small").
Existing dam?
The user indicates by selecting from the drop-down list whether or not there is an existing dam at
the small hydro project site. The presence or absence of an existing dam at the site can
dramatically affect the cost of a project. This fact is taken into account in the formula used to
calculate the cost of civil works. Note that if the existing dam is old, it may not meet current dam
safety standards. In this case, an appropriate adjustment can be made to the calculated "Civil
works (other)" cost category.
Note that in RETScreen, it is assumed that a new dam will be built primarily to divert water and
not to develop head. If this is not the case (e.g., a dam will be built for the purposes of creating a
reservoir and head) an appropriate adjustment can also be made to the calculated "Civil works
(other)" cost category.
New dam crest length
The user enters the estimated crest length of the required dam. This value is used in the formula
to calculate the cost of the civil works. A field visit will normally be required to estimate the
anticipated length of a required dam unless detailed mapping is available.
Rock at dam site?
The user indicates by selecting from the drop-down list whether or not there is rock at the small
hydro project site. The presence or absence of suitable rock at a proposed dam site affects the
cost of the project and is taken into account in the formula to calculate the cost of civil works.
HYDRO.35