CT: At the start of a SHP project in an existing infrastructure,
a first issue is to define if the existing penstocks and channels are suitable for electricity production, which implies mainly to check their mechanical resistance (nominal pressure for a penstock) and head losses.
In general, head losses are acceptable if at nominal discharge they are lower than 10% of the difference in levels, or in other words if the penstock efficiency is higher than 90%. Indeed, this corresponds to the present state of the art for equipment that uses optimally the water resource.
S: http://www.esha.be/fileadmin/esha_files/documents/SHAPES/Multipurpose%20schemes%20brochure%20SHAPES.pdf (last access: 27 February 2015)
N: 1. In the fields of Fluid Mechanics and Hydraulics (Physics), Hydrology and Hydrography, Transport of Water (Water Supply), “head loss” is the drop in the sum of pressure head, velocity head, and potential head between two points along the path of a flowing fluid.
What engineers call head loss or lost head is more specifically the energy lost by a unit weight of water because of surface resistance within the conduit, mechanical energy being converted into nonrecoverable heat energy.
loss of head: term standardized by the British Standards Institution (British Standard No. 4118).
2. In the fields of Electric Currents and Solar Energy, the term in use is “tare loss”: Loss (in current) caused by a charge controller.
S: 1 & 2. TERMIUMPLUS.