Hydropower

Question 1

Max power found at

Answer 1

1/3 gH

Question 2

Energy available at the end of the pipe

Answer 2

2/3 gH

Question 3

Pipe transmission efficiency?

Answer 3

energy extracted / total available energy

= ((2/3)*gH)/gH = 2/3

Question 4

General transmission efficiency equation

Answer 4

1-(Losses/gH)

Question 5

List 3 types of turbine and explain them

Answer 5

1. • Pelton wheel - Water flows symmetrically with the turbine
2. Turgo - jet passes through the turbine from left to right
3. Francis - water flows through. spiral casing

Question 6

List an example of a hydro power plant

Answer 6

Three Gorges Dam - 22.5 GW output, 26 700MW Francis turbines, 600km, 38 billion cost

Question 7

List the three main types of hydropower

Answer 7

run-of-river - channels river flow through a turbine
storage hydropower - dam stores water in reservoir
pumped storage - water pumped from 1 res to other at low demand and generation turned on at high demand

Question 8

Total potential energy?

Answer 8

E = mgH

Question 9

Energy per unit mass?

Answer 9

E = gH

Question 10

Formula for the Bernoulli equation

Answer 10

E = (P/p)+(V^2/2)+gz1 - losses = same for P2

Question 11

Losses equation

Answer 11

(4fl/d)*Vave^2/2

Question 12

Equation for overall efficiency N(o/a)

Answer 12

generator efficiency * Turbine efficiency * transmission efficiency

Question 13

Equation of power for any hydro electric power plant

Answer 13

P = N(o/a)pQgH

Question 14

Main disadvantages of hydropower

Answer 14

• risk of flooding
• risk of catastrophe (seismic)
• visual issues
• social displacement
• Not many high up areas that can be used generally
• pumped storage requires large amount of power

Question 15

formula for average flow rate

Answer 15

Vave = Q/A