Renewable Energy Systems Flashcards
7 cards from real EMP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Renewable Energy Systems flashcards as text
How does a pumped hydro energy storage (PHES) facility store electrical energy?
Answer: Uses surplus electricity to pump water to an upper reservoir for later release through turbines
PHES stores energy as gravitational potential energy by pumping water uphill during low-demand periods and recovers it by releasing water through turbines when demand is high.
What effect does increasing a PV module's cell temperature have on its power output?
Answer: Power output decreases because open-circuit voltage drops
Rising cell temperature reduces open-circuit voltage (Voc) at roughly -0.3% to -0.5%/°C, which decreases overall module power output despite a slight increase in short-circuit current.
An offshore wind project has a hub height of 120 m and measures wind speed of 9 m/s at that height. Using the wind power equation P = ½ρAv³, if wind speed increases to 10 m/s, how does power output change approximately?
Answer: Increases by about 37%
Power scales with the cube of wind speed: (10/9)³ ≈ 1.372, so power increases approximately 37% for an 11% increase in wind speed.
In the context of solar resource assessment, what does GHI represent?
Answer: Global Horizontal Irradiance — total solar radiation on a horizontal surface
Global Horizontal Irradiance (GHI) is the total shortwave radiation received on a horizontal surface and is the primary metric used in solar resource evaluation and energy yield modeling.
What is 'curtailment' in the context of renewable energy systems?
Answer: Intentional reduction of a renewable generator's output below its available capacity
Curtailment occurs when grid operators instruct renewable generators to reduce output—often due to transmission constraints or oversupply—resulting in foregone clean energy production.
Which type of solar collector is best suited for generating high-temperature industrial process heat above 200°C?
Answer: Concentrating parabolic trough collector
Concentrating solar collectors like parabolic troughs use mirrors to focus sunlight onto a receiver, achieving fluid temperatures of 300–550°C suitable for industrial processes and power generation.
What does a negative Levelized Cost of Energy (LCOE) imply for a renewable project with high production tax credits?
Answer: Subsidies and tax credits exceed total lifetime costs, making each MWh economically net-positive for the developer
When production tax credits and other incentives exceed the sum of capital, O&M, and financing costs, LCOE can technically go negative, indicating the developer earns more from incentives than it costs to produce each MWh.