Technology Status - NET Nowak Energie & Technologie AG

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The natural factors which affect SHP potential are the quantity of water flow
and the height of the head. Flow roughly relates to average annual
precipitation and the head depends, basically, on topography. The main
requirement for a successful hydropower installation is an elevated head,
either natural or artificial, from which water can be diverted through a pipe
into a turbine coupled to a generator that converts the kinetic energy of
falling water into electricity. The water is then discharged, usually through a
tube or diffuser, back into the river at a lower level.
The theoretical power available in a volume of water (Q) is the mass of the
water times the height or head (H) the water can fall. In reality, losses due to
imperfections in the design of machinery and pipelines have to be
considered in every hydropower system. Internal friction in pipelines and
channels as water travels towards the turbine causes a loss of potential
energy in the system. Hence the head used in calculations is the net head,
defined as the potential energy which reaches the turbine system. Similarly,
friction and heat losses occur in the turbine, the gearbox and the electric
generator. As a rule of thumb, power is equal to seven times the product of
the flow (Q) and gross head (H) at the site:
P [kW] = 7QH Where: Q = cubic metres per second and
H = net head in metres
Producing one kWh at a site with a 10m head requires ten times the water
flow of a site with a 100m head.
SHP can generally be divided into three different categories depending on
the type of head and the nature of the plant:
● High-head power plants are the most common and generally include a
dam to store water at a higher elevation. These systems are commonly
used in mountainous areas.
● Low-head hydroelectric plants generally use heads up to a few metres in
elevation or simply function on run-of-river. Low-head systems are
typically built along rivers.
● Supplemental hydropower systems are generating facilities where the
hydropower is subordinate to other activities like irrigation, industrial
processes, drinking water supply or wastewater disposal. Electricity
production is thus not the prime objective of the plant but often a useful
by-product.
SMALL HYDROPOWER X2