CPE CPE Energy Management & Efficiency 2 — Questions and Answers
Question 1: What is the purpose of a power factor correction capacitor bank in a plant?
- Reduce reactive power demand and lower utility penalties (Correct answer)
- Increase voltage levels across feeders
- Store backup energy for outages
- Filter harmonics from motor drives
Correct answer: Reduce reactive power demand and lower utility penalties
Capacitor banks supply reactive power locally, improving power factor and reducing the reactive current drawn from the utility, which lowers demand charges.
Question 2: Which heat recovery method captures waste heat from compressed air system aftercoolers?
- Using the rejected heat for space heating or process water preheating (Correct answer)
- Routing exhaust air through a heat pump
- Installing an economizer on the air compressor inlet
- Adding a recuperator to the exhaust stack
Correct answer: Using the rejected heat for space heating or process water preheating
Up to 90% of the energy input to an air compressor is rejected as heat, which can be recovered from aftercoolers to heat facility spaces or process water.
Question 3: What does an energy audit's 'simple payback period' calculation determine?
- The time required for energy savings to equal the initial investment cost (Correct answer)
- The net present value of an efficiency project
- The percentage of energy saved annually
- The carbon reduction from an upgrade
Correct answer: The time required for energy savings to equal the initial investment cost
Simple payback period is calculated by dividing the capital cost of an improvement by the annual energy cost savings it produces.
Question 4: In a compressed air system, what is the most common cause of energy waste?
- Leaks in distribution piping and fittings (Correct answer)
- Oversized air receivers
- Excessive dryer capacity
- Underloaded compressors
Correct answer: Leaks in distribution piping and fittings
Compressed air leaks can account for 20–30% of a compressor's output, making leak detection and repair one of the highest-ROI energy conservation measures.
Question 5: Which federal program provides energy benchmarking and labeling for commercial and industrial buildings in the US?
- ENERGY STAR Portfolio Manager (Correct answer)
- EPA RCRA Energy Tracker
- DOE LEED Industrial
- ASHRAE Green Label
Correct answer: ENERGY STAR Portfolio Manager
ENERGY STAR Portfolio Manager is the EPA's online tool for tracking energy and water consumption and benchmarking facility performance against peers.
Question 6: A steam trap that continuously passes steam is said to be:
- Failed open (blowing through) (Correct answer)
- Failed closed (plugged)
- Short-cycling
- Waterlogged
Correct answer: Failed open (blowing through)
A steam trap that fails open allows live steam to pass continuously into the condensate return system, wasting significant energy.
CPE CPE Energy Management & Efficiency 2
What is the purpose of a power factor correction capacitor bank in a plant?