Hydroelectric Power Generation - Renewable Energy: Technology, Economics and Environment - page 373

selected plants that will be subject to the following economic analyses. It has to be
considered that run-of-river power stations - as opposed e.g. to wind energy con-
version systems or photovoltaic plants - are power stations that are largely deter-
mined by the prevailing local conditions. Thus material input - and with it, the
costs involved - can sometimes vary significantly for different run-of-river power
stations. Generally applicable cost estimates can therefore only be made to a very
limited extent.
8.3.1 Economic analysis
Hydroelectric power stations are characterised by a number of possible design
types. Therefore only selected reference plants can be analysed here, that ought to
be seen as examples for possible plant configurations defined by the specific local
conditions. This is particularly true for the structural components (i.e. water in-
take, head and tailraces or penstock, power house), which sometimes vary a lot in
different hydroelectric power stations.
Within the following analysis we will take a closer look at four hydroelectric
power stations, as their reference technology is typical for extensive territories
throughout the world (Table 8.1). According to this it is distinguished between
two small hydroelectric power plants with an installed electrical power of 32 and
300 kW respectively, and two larger plants with a power of 2.2 and 28.8 MW re-
spectively.
− 32 kW low-pressure (Plant I). The water is diverted at a small dam and then
processed with a head of 8.2 m via a 110 m long fiberglass pipe with a Kaplan
turbine. The electrical energy generated by a directly coupled, synchronous in-
duction generator is fed into low voltage grid.
− 300 kW low-pressure (Plant II). The power station utilises the head of 4.6 m,
created by a concrete dam followed by bypass reach of 200 m. From the intake
structure, the headwater channel leads directly to the power station. The elec-
trical energy generated by a Kaplan turbine connected by a transmission to the
synchronous generator is fed into the medium voltage grid near the power sta-
tion via a transformer.
− 2,200 kW low-pressure (Plant III). This run-of-river power station is designed
as a river power station. The head of around 6 m is created with a dam. The
backwater reach of almost 2,000 m is secured by longitudinal dykes. The hy-
draulic energy is converted into mechanical energy by a Kaplan turbine and
then further converted into electrical energy by a synchronous generator. This
electrical energy is fed into the medium voltage grid next to the power station
via a transformer.
− 28,800 kW low-pressure (Plant IV). This run-of-river power station is also de-
signed as a river power station; the powerhouse is located in the riverbed. With
a catchment reach of approximately 8.8 km, it achieves a head of 8.3 m. The
two Kaplan bulb turbines have a combined capacity of 425 m 3 /s and the elec-