Renewable Energy Technologies & Applications Flashcards

Which ocean energy technology converts the temperature difference between warm surface water and cold deep water into electricity?

Answer: Ocean thermal energy conversion (OTEC)

OTEC exploits the thermal gradient between warm surface seawater (~25°C) and cold deep seawater (~5°C) to drive a thermodynamic cycle and generate electricity.

In a grid-tied PV system, what happens to power generation when the utility grid goes down (without a battery backup)?

Answer: The inverter shuts down to prevent islanding

Grid-tied inverters are required to detect grid loss and shut down immediately (anti-islanding protection) to prevent energizing lines that utility workers might contact.

What is the Betz limit and what value does it represent?

Answer: Maximum theoretical efficiency of a wind turbine, approximately 59.3%

The Betz limit, derived by Albert Betz in 1919, states that no wind turbine can capture more than 16/27 ≈ 59.3% of the kinetic energy in wind.

Which solar cell technology currently holds the highest confirmed single-junction efficiency record for terrestrial flat-plate cells?

Answer: Gallium arsenide (GaAs) single crystal

Single-crystal GaAs cells hold the highest confirmed efficiency for single-junction terrestrial flat-plate cells, exceeding 29%, due to their near-ideal bandgap and material quality.

What is 'levelized cost of energy' (LCOE) used to measure?

Answer: The average cost per unit of electricity over a plant's lifetime

LCOE represents the net present value of all costs (capital, O&M, fuel) divided by lifetime energy production, enabling comparison across different generation technologies.

Which type of electrolyzer technology is most suitable for pairing with intermittent renewable energy sources due to its fast response time and ability to operate at partial load?

Answer: Proton exchange membrane (PEM) electrolyzer

PEM electrolyzers can ramp rapidly and operate efficiently across a wide load range (5–100%), making them well-suited for coupling with variable solar and wind generation.

A biomass power plant using a combined heat and power (CHP) configuration achieves what primary benefit over electricity-only generation?

Answer: Higher overall fuel utilization efficiency

CHP (cogeneration) captures waste heat for useful purposes such as space heating or industrial processes, raising overall fuel-to-useful-energy efficiency from ~25–35% to 70–85%.