Geothermal and Hydropower Flashcards
7 cards from real REP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Geothermal and Hydropower flashcards as text
Which factor most directly determines the power output of a hydropower turbine?
Answer: Net hydraulic head and volumetric flow rate
Hydropower output (P = ρgQHη) is primarily governed by net hydraulic head (H) and volumetric flow rate (Q), along with water density and turbine efficiency.
In the context of geothermal energy, what is 'reinjection' and why is it practiced?
Answer: Returning spent geothermal brine to the reservoir to sustain pressure and reduce surface disposal
Reinjection returns cooled geothermal brine back into the reservoir, maintaining reservoir pressure, extending field life, and minimizing surface disposal of mineral-laden fluid.
A Kaplan turbine is preferred over a Francis turbine for which site condition?
Answer: Low head (below 40 m) with high flow and variable flow rates
Kaplan turbines have adjustable runner blades suited for low-head, high-flow sites with variable discharge, maintaining efficiency across a wide range of flow conditions.
What is the significance of the 'capacity factor' for a hydropower plant?
Answer: The ratio of actual energy generated to maximum possible energy at full capacity over a period
Capacity factor is the ratio of actual annual energy output to the theoretical maximum if the plant ran at full nameplate capacity continuously, reflecting real-world hydrology and operational constraints.
Which U.S. federal agency is primarily responsible for licensing non-federal hydropower projects?
Answer: Federal Energy Regulatory Commission (FERC)
FERC issues licenses and exemptions for non-federal hydropower projects under the Federal Power Act, overseeing project construction, operation, and environmental conditions.
Cavitation in hydropower turbines is most likely to occur under which operating condition?
Answer: Low local pressure causing water to vaporize near turbine blades
Cavitation occurs when local pressure at the turbine runner drops below the vapor pressure of water, forming vapor bubbles that collapse violently and erode turbine components.
What is the approximate global average geothermal heat flux at the Earth's surface?
Answer: 0.065 W/m²
The global average geothermal heat flux is approximately 0.065 W/m² (65 mW/m²), far less than solar irradiance but sufficient for exploitation in high-gradient volcanic and tectonic zones.