REP Renewable Energy Technologies & Applications 3

Question 1

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

Accepted Answer

Ocean thermal energy conversion (OTEC)

Answer

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.

Question 2

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

Accepted Answer

The inverter shuts down to prevent islanding

Answer

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.

Question 3

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

Accepted Answer

Maximum theoretical efficiency of a wind turbine, approximately 59.3%

Answer

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.

Question 4

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

Accepted Answer

Gallium arsenide (GaAs) single crystal

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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

(REP) Certified Renewable Energy Professional Practice Test

(REP) Certified Renewable Energy Professional Practice Test

REP Renewable Energy Technologies & Applications 3