CEA Energy Storage & Grid Integration 3

Question 1

A 100 MWh battery discharges at 50 MW for 2 hours, then must recharge. If round-trip efficiency is 85%, how much energy (MWh) must be input to fully restore the battery?

Accepted Answer

117.6 MWh

Answer

Energy in = energy out / RTE = 100 MWh / 0.85 ≈ 117.6 MWh must be charged to recover 100 MWh of usable capacity.

Question 2

What is 'time-of-use (TOU) arbitrage' in the context of energy storage?

Accepted Answer

Charging storage during low-price periods and discharging during high-price periods

Answer

TOU arbitrage captures the price spread by charging when electricity rates are low (off-peak) and discharging when rates are high (on-peak).

Question 3

Which type of energy storage technology is most suitable for seasonal (multi-month) storage due to negligible self-discharge?

Accepted Answer

Compressed hydrogen

Answer

Hydrogen produced via electrolysis can be stored for months in tanks or geological formations with minimal energy loss, unlike batteries or flywheels.

Question 4

In the context of grid services, what does 'spinning reserve' require of a storage resource?

Accepted Answer

The resource must be online and able to increase output within 10 minutes

Answer

Spinning reserve requires resources that are already synchronized to the grid and can ramp up to full capacity within 10 minutes to cover sudden generation loss.

Question 5

What is the primary function of a Battery Management System (BMS) in a grid-scale BESS?

Accepted Answer

Monitor cell voltage/temperature and balance cells to protect battery health

Answer

The BMS monitors individual cell conditions and performs balancing to prevent overvoltage, undervoltage, and thermal runaway, extending battery life.

(CEA) Certified Energy Analyst Practice Test

(CEA) Certified Energy Analyst Practice Test

CEA Energy Storage & Grid Integration 3