Pass the AEE Energy Management CEM Questions and answers with CertsForce

To determine the simple payback period for the energy-saving project, we need to apply the standard formula used in energy management as per the Association of Energy Engineers (AEE) Certified Energy Manager (CEM) guidelines. The simple payback period is a widely used metric in energy efficiency projects to evaluate how long it takes for the initial investment to be recovered through net savings. Let’s break this down step-by-step using the provided data and CEM-aligned methodology.

Step 1: Understand the Simple Payback Formula

Formula: Simple Payback Period (years)=Initial Investment CostNet Annual Savings\text{Simple Payback Period (years)} = \frac{\text{Initial Investment Cost}}{\text{Net Annual Savings}}Simple Payback Period (years)=Net Annual SavingsInitial Investment Cost​

Definition: The simple payback period represents the time (in years) required for the cumulative savings to equal the initial investment, without considering the time value of money (e.g., discount rates or inflation).

CEM Reference: AEE CEM training materials emphasize this formula in the "Energy Economics" section, where simple payback is a fundamental tool for assessing project feasibility.

Step 2: Identify Given Data

Initial Investment Cost: $540,000 (one-time cost of the project).

Annual Energy Savings: $160,000 per year (benefit from the project).

Annual Maintenance Costs: $25,000 per year (additional cost incurred due to the project).

Net Annual Savings: This must account for both the savings and the costs incurred annually.

Step 3: Calculate Net Annual Savings

Definition: Net annual savings is the difference between the annual energy savings and any additional annual costs (e.g., maintenance).

Verification: The problem specifies maintenance costs as an ongoing expense tied to the project, which reduces the effective savings. CEM guidelines require including such costs in payback calculations unless explicitly stated otherwise.

Step 4: Compute the Simple Payback Period

Apply the Formula: Simple Payback Period=Initial Investment CostNet Annual Savings\text{Simple Payback Period} = \frac{\text{Initial Investment Cost}}{\text{Net Annual Savings}}Simple Payback Period=Net Annual SavingsInitial Investment Cost​ Simple Payback Period=540,000135,000=4.0 years\text{Simple Payback Period} = \frac{540,000}{135,000} = 4.0 \, \text{years}Simple Payback Period=135,000540,000​=4.0years

Result: The payback period is exactly 4.0 years, meaning it takes 4 years for the net savings to recover the initial investment.

Step 5: Validate Against Options

Options:A. 2.0 yearsB. 3.0 yearsC. 4.0 yearsD. 5.0 years

Check:

If we ignored maintenance costs (incorrectly), payback would be 540,000160,000=3.375 \frac{540,000}{160,000} = 3.375 160,000540,000​=3.375 years, which rounds to 3.4—not an exact match for any option.

With maintenance costs included, 540,000135,000=4.0 \frac{540,000}{135,000} = 4.0 135,000540,000​=4.0, which matches option C precisely.

Conclusion: Option C (4.0 years) is correct based on the net savings approach.

Electric utility companies transmit power at high voltages primarily to reduce transmission power losses, which are proportional to the square of the current (I²) multiplied by the resistance (R) of the transmission lines. This relationship is expressed by the formula for power loss: P_loss = I²R.​

Key Points:

Power Loss and Current Relationship:Power losses in transmission lines are directly proportional to the square of the current flowing through them. Reducing the current decreases these losses significantly.

High Voltage Transmission:By increasing the transmission voltage, the current required to deliver the same amount of power decreases. This is because power (P) is the product of voltage (V) and current (I): P = VI. For a given power level, increasing voltage allows for a corresponding decrease in current.

Reduced I²R Losses:Lower current results in reduced I²R losses, enhancing the efficiency of power transmission over long distances.

Conclusion:

Transmitting power at high voltages minimizes transmission losses, making it the most efficient method for long-distance electrical power delivery. Therefore, the correct answer is C. Transmission power losses (I²R) are less.

Understanding the environmental impacts of various refrigerants is crucial for energy managers. Let's analyze each statement:​en.wikipedia.org

A.R-407C is a blended Hydro Fluoro Carbon or near Azeotropic mixture, and can be used as a replacement for R-22 in commercial applications:This statement is correct. R-407C is a blend of HFCs designed to replace R-22 in air conditioning systems.

B.R-11 and R-12 are Chloro Fluoro Carbons with significant ozone depleting potential:This is correct. R-11 and R-12 are CFCs known for their high ozone depletion potential.

C.R-1234yf is a Hydro Fluoro Olefin with zero ozone depleting potential, and little global warming potential:Correct. R-1234yf is an HFO with negligible ozone depletion and low global warming potential.

D.R-22 is a Hydro Chloro Carbon with significant ozone depleting potential and significant global warming impact:This statement is incorrect.R-22 is a Hydrochlorofluorocarbon (HCFC), not a Hydro Chloro Carbon.While it does have ozone-depleting potential, its global warming potential is considered moderate, not significant.

E.R-32 and R-134a are Hydro Fluoro Carbons with zero ozone depleting potential, and significant global warming impact:This is correct. Both R-32 and R-134a are HFCs with no ozone depletion potential but have considerable global warming potential.

Conclusion:

The incorrect statement is D. R-22 is a Hydro Chloro Carbon with significant ozone depleting potential and significant global warming impact. Therefore, the correct answer is D.