Microhydropower Calculator Logic

Handling various elevation service endpoints

ESRI Web Services give a in square kilometers (area_sqkm) and h in meters (h_esri). Assume LiDAR web service gives h in feet.

Some pseudo-code:

# Calculate Area and Head in metric and imperial
area_sqmi = area_sqkm * 0.386
if elevation_service_esri:
  h_meters = h_esri
  h_feet = h_esri * 3.281
elif elevation_service_nys_lidar:
  h_feet = h_lidar
  h_meters = h_lidar * 0.3048
else:
  #(fallback, assume service is coming from Esri)

Hydropower Equation in Imperial/English Units:

1.6 cfs/sq.mi. is a general estimate of the amount of water per sq. mile a watershed will yield. The value of X for Qe “lays between 0.1 cfs/sqmi x drainage area and 0.5 cfs/sqmi x drainage area” (per Current Hydro). Good enough for consistent planning purposes.

a = area_square_miles
h = h_feet
qt = a * 1.6 #cubic feet per second
y = 1.6 # watershed yield per square mile, in cubic feet per second per square mile.
qe = a * y # cubic feet per second
qu = qt - qe

# Power in KW
e = 0.7 #efficiency constant (percentage)
p = (qu x h/11.8)  x e # kW, where q = cubic feet per second, h = feet, and e = efficiency constant

See http://www.homepower.ca/data_tables.htm#power

Hydropower Equation in SI Units:

Like above, but skip worrying about A, go straight to Q.

Note that a is the same a as above (a = area_sqmi), and the conversion back to SI units is handled by the 0.0283 conversion factor)

h = h_meters
# `a` is the same `a` as above (`a = area_sqmi`)
# the conversion back to SI units is handled by the `0.0283` conversion factor
qt= a * 1.6 * 0.0283 #cubic meters per second
# again, the conversion factor of 0.0283 handles the conversion from English back to SI, 
# no reason to change the range of values for y
qe = a * y * 0.0283 # cubic meters per second
qu = qt - qe

# Power in KW
e = 0.7 #efficiency constant (percentage)
p = qu x h x 9.8 x e # kW, where q = cubic meters per second, h = meters, and e is efficiency constant