REP Geothermal and Hydropower 5

Question 1

What is the typical round-trip efficiency range for pumped-storage hydropower systems?

Accepted Answer

70–85%

Answer

Pumped-storage hydropower achieves round-trip efficiencies of approximately 70–85%, accounting for losses in pumping, penstock friction, turbine/generator conversion, and transformer stages.

Question 2

Which U.S. state leads in installed geothermal electricity generating capacity?

Accepted Answer

California

Answer

California leads the U.S. in geothermal capacity, largely due to The Geysers in Sonoma and Lake counties, the world's largest complex of geothermal power plants operating since 1960.

Question 3

A hydropower project's 'hydraulic head' decreases by 20% due to drought-reduced reservoir levels. Assuming constant efficiency, how does this affect power output?

Accepted Answer

Power decreases by approximately 20%

Answer

Since power output is directly proportional to hydraulic head (P = ρgQHη), a 20% reduction in head causes approximately a 20% reduction in power output, assuming flow rate and efficiency remain constant.

Question 4

What does the term 'minimum environmental flow' (or 'minimum instream flow') refer to in hydropower project management?

Accepted Answer

The legally required minimum discharge that must be released downstream to sustain ecosystem functions

Answer

Minimum environmental flow is the regulated minimum discharge that hydropower operators must release downstream to protect aquatic habitat, riparian vegetation, and water quality below the dam.

Question 5

In ground-source heat pump systems, what is the 'coefficient of performance' (COP) measuring?

Accepted Answer

The ratio of heat energy delivered to electrical energy consumed by the heat pump

Answer

COP is the ratio of useful heat output (or cooling effect) to the electrical energy input consumed by the heat pump compressor, with typical ground-source systems achieving COPs of 3–5.

(REP) Certified Renewable Energy Professional Practice Test

(REP) Certified Renewable Energy Professional Practice Test

REP Geothermal and Hydropower 5