Regional Potential

Подпись: Pf Подпись: 9.8 x 8760 xQxH 8760 x 360 Подпись: (8.4)

To calculate Pf(region) or linear potential for a specific region, requires to know the elevation above sea-level of the individual basins (Hi) and the mean run-off of sev­eral basins; an estimate of the theoretical linear value of the per annum potential, in millions of kWh (kWh.106), is now possible (Pf). Taking Hmed as the median of the Hi values, and V being the precipitations’ run-off, expressed in millions of m3, the potential is found through (8.5):

Pf = VxHmed/367 (8.5)

A region’s potential can thus be given in kWh/km2, but, particularly in less de­veloped countries, it often is not precised due to the lack of long-term hydrological data. As usual economic potential is lower than the theoretical potential for such reasons as several streams having too small a discharge or waters being diverted for irrigation. In some cases not the “value” but environmental constraints—natural or social—may make the implantation of a generating station unacceptable. The ratio between two values may well vary around 1-5. Finally, the economic potential value may vary in time.

Another estimation of extractable power (Px), calculated in W/m2, is given by (8.6) in which typical values of the extraction efficiency factor (p), the velocity profile factor (Ks) and the spring/neap tide factor (Kn) are respectively 0.25, 0.424 and 0.57; w is the fluid density in kg/m3.

Px = 1/2pwKsKnV3 (8.6)

Подпись: (8.7)Px = 0.3 wV3

Updated: September 25, 2015 — 5:50 am