REP Geothermal and Hydropower 2

Question 1

What is the primary environmental concern associated with geothermal power plants using open-loop hydrothermal systems?

Accepted Answer

Emission of hydrogen sulfide (H₂S) gas

Answer

Open-loop hydrothermal systems release hydrogen sulfide (H₂S), a toxic gas naturally present in geothermal fluids, requiring scrubbing systems to meet air quality standards.

Question 2

A run-of-river hydropower project generates electricity without a large reservoir. What is the main trade-off compared to storage hydropower?

Accepted Answer

Less predictable and dispatchable power output

Answer

Run-of-river projects cannot store water, so generation fluctuates with natural streamflow, making output less predictable and limiting dispatchability compared to reservoir-based plants.

Question 3

In binary-cycle geothermal plants, what role does the working fluid (e.g., isobutane or isopentane) play?

Accepted Answer

It absorbs heat from geothermal brine and vaporizes to drive a turbine

Answer

In binary-cycle plants, a secondary working fluid with a lower boiling point absorbs heat from geothermal brine via a heat exchanger, vaporizes, and drives a turbine before being condensed and recirculated.

Question 4

The penstock in a hydropower facility performs which function?

Accepted Answer

Conveys pressurized water from the forebay or reservoir to the turbine

Answer

The penstock is a large pipe or conduit that carries water under pressure from the intake or forebay downhill to the turbine, converting potential energy into kinetic energy.

Question 5

Which geothermal resource type is characterized by temperatures above 150°C and is best suited for direct electricity generation?

Accepted Answer

High-enthalpy hydrothermal reservoirs

Answer

High-enthalpy hydrothermal reservoirs with temperatures above 150°C contain sufficient thermal energy to flash steam or operate binary cycles for economical electricity generation.

(REP) Certified Renewable Energy Professional Practice Test

(REP) Certified Renewable Energy Professional Practice Test

REP Geothermal and Hydropower 2