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| Section | Weight | Objectives |
|---|---|---|
| Energy Accounting and Economics | 10-15% | - Utility rate structures and tariffs - Energy price forecasting - Financial analysis techniques (ROI, NPV, IRR) - Energy cost accounting and allocation - Life cycle cost analysis (LCCA) |
| Heating, Ventilating, and Air Conditioning (HVAC) | 12-18% | - HVAC system types and components - Load calculations - Equipment efficiency ratings - Controls and optimization - Psychrometrics - Heat transfer principles - Indoor air quality |
| Facilities Management | 8-12% | - Operations and maintenance best practices - Commissioning and re-commissioning - Preventive maintenance programs - Building automation systems (BAS) - Monitoring and targeting (M&T) |
| Energy Project Implementation | 8-12% | - Project risk management - Project financing models - Implementation strategies - Energy service companies (ESCOs) - Performance contracting (ESPC) - Measurement and verification (M&V) |
| Renewable Energy Technologies | 8-12% | - Geothermal systems - Energy storage technologies - Wind energy systems - Solar photovoltaic systems - Solar thermal systems - Biomass and bioenergy |
| Building Envelope | 8-12% | - Windows and glazing systems - Air leakage and infiltration - Insulation types and R-values - Thermal envelope analysis - Daylighting and shading |
| Environmental and Regulatory Compliance | 5-10% | - EPA regulations (Clean Air Act, Clean Water Act) - Energy reporting requirements - Carbon footprint calculation - Green building standards (LEED, ENERGY STAR) - Sustainability reporting |
| Electric Power Systems | 10-15% | - Power distribution systems - Motors and drives - Harmonics and power quality - Power factor correction - Standby power systems - Lighting systems and controls |
| Energy Auditing | 15-20% | - Baseline establishment - Metering and measurement equipment - Data collection and analysis - Audit procedures and methodologies - Audit report writing - Types of energy audits (preliminary, detailed, investment-grade) |
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NEW QUESTION # 126
Which of the advantages listed below, makes an ice TES system more preferred over a water TES system, when a load shifting strategy is considered?
Answer: D
Explanation:
To determine which advantage makes an ice Thermal Energy Storage (TES) system more preferred over a water TES system for a load shifting strategy, we need to evaluate each option based on the principles of thermal energy storage as outlined in the Association of Energy Engineers (AEE) Certified EnergyManager (CEM) training materials. Load shifting involves storing energy (cooling capacity) during off-peak periods and releasing it during peak demand, making storage efficiency and capacity critical. Let's analyze each option step-by-step.
Step 1: Understand Ice TES vs. Water TES in Load Shifting
* Ice TES: Uses the latent heat of fusion of water (ice melting) to store cooling energy. Ice is formed during off-peak hours (e.g., overnight) and melted during peak hours to provide cooling.
* Water TES: Uses the sensible heat capacity of water, storing chilled water (typically 4-6°C) to provide cooling.
* Load Shifting Goal: Maximize cooling storage in minimal space and cost, shifting electrical demand from peak to off-peak periods.
* CEM Reference: CEM materials in the "Thermal Energy Storage" section highlight ice TES for its high energy density and compact storage, contrasted with water TES for simpler operation but larger volume requirements.
Step 2: Evaluate Each Option
Option A: Ice-storage systems operate with a higher coefficient of performance (COP)
* Analysis:
* COP Definition: COP = (Cooling Output) / (Energy Input). For TES, this relates to the chiller's efficiency.
* Ice TES: Requires chillers to operate at lower temperatures (e.g., -5°C to 0°C) to freeze water, which typically reduces chiller COP (e.g., 3-4) compared to water TES chillers operating at 4-6° C (COP ~5-6).
* Reality: Ice TES systems often have a lower COP due to the additional energy needed for phase change, though total system efficiency may improve with load shifting benefits.
* CEM Reference: CEM notes that ice TES energy input is higher per unit of cooling due to lower evaporating temperatures, contradicting a "higher COP" claim.
* Conclusion: This statement is incorrect and not an advantage for ice TES in load shifting.
Option B: Ice-storage systems require smaller storage tanks since ice has a higher energy storage density
* Analysis:
* Energy Storage Density:
* Ice TES: Relies on latent heat of fusion = 334 kJ/kg (80 kcal/kg or ~144 Btu/lb). This is the energy absorbed/released when water freezes/melts, far exceeding sensible heat.
* Water TES: Relies on sensible heat = cp##T c_p \cdot \Delta T cp##T, where cp=4.18 kJ
/kg\cdotp°C c_p = 4.18 \, \text{kJ/kg °C} cp=4.18kJ/kg\cdotp°C (1 Btu/lb °F). For a typical #T=10°C\Delta T = 10°C#T=10°C (e.g., 4°C to 14°C), energy stored = 4.18×10=41.
8 kJ/kg 4.18 \times 10 = 41.8 \, \text{kJ/kg} 4.18×10=41.8kJ/kg (~20 Btu/lb).
* Comparison: Ice stores ~8 times more energy per kg than water for a 10°C range (334 vs.
41.8 kJ/kg).
* Volume Impact: Ice's density (~917 kg/m³) is slightly less than water (~1000 kg/m³), but the latent heat advantage dominates, reducing required tank volume significantly.
* Load Shifting: Smaller tanks mean less space and potentially lower capital costs, a key advantage for peak load management.
* CEM Reference: CEM training emphasizes ice TES's high energy density as a primary reason for its preference in space-constrained load shifting applications.
* Conclusion: This statement is correct and a clear advantage for ice TES.
Option C: Water-storage systems require smaller storage tanks since water has a higher density than ice
* Analysis:
* Density: Water = 1000 kg/m³; Ice = 917 kg/m³. Water is denser, but density alone doesn't determine storage size in TES.
* Energy Storage: As calculated, water's sensible heat capacity (e.g., 41.8 kJ/kg for 10°C) is much lower than ice's latent heat (334 kJ/kg). To store the same cooling capacity, water TES requires
~8 times more mass and thus larger tanks (even accounting for density differences).
* Implication: Water TES tanks are larger, not smaller, contradicting the statement.
* CEM Reference: CEM materials note water TES's larger volume requirements as a disadvantage compared to ice TES.
* Conclusion: This statement is incorrect and not an advantage for ice TES (it favors water TES incorrectly).
Option D: Ice-storage systems require lower maintenance due to lower pumping volume
* Analysis:
* Pumping Volume: Ice TES often uses glycol or brine solutions to transfer heat at lower temperatures, requiring pumps sized for smaller volumes due to concentrated coolingcapacity.
Water TES circulates larger volumes of chilled water. However, "lower pumping volume" doesn' t directly translate to "lower maintenance."
* Maintenance: Ice TES systems are more complex (ice-making equipment, heat exchangers), potentially increasing maintenance (e.g., defrost cycles, corrosion from brine). Water TES is simpler, often with lower maintenance needs.
* CEM Reference: CEM discusses ice TES complexity as a trade-off for its density advantage, not a maintenance benefit.
* Conclusion: This statement is questionable and not a primary advantage for load shifting.
Step 3: Identify the Key Advantage for Load Shifting
* Load Shifting Context: The goal is to store maximum cooling capacity efficiently during off-peak hours. Option B (smaller tanks due to higher energy storage density) directly supports this by reducing space and installation costs, a critical factor in TES design per CEM guidelines.
* Elimination:
* A: Incorrect (lower COP, not higher).
* C: Incorrect (water TES tanks are larger).
* D: Weak (maintenance isn't clearly lower; not the primary driver).
* B: Correct and relevant.
NEW QUESTION # 127
An air-conditioning unit delivers 10,000 kJ/h (thermal cooling). The equipment uses single-phase electrical power at 220-volt and 5.25 amps with a power factor of 100%. Calculate the coefficient of performance (COP).
Answer: D
Explanation:
NEW QUESTION # 128
Using the natural gas combustion efficiency tables in your workbook, find the combustion efficiency (based on higher-heating value) of a natural-gas-fired boiler if the excess air level is measured at 31.9% and the stack temperature rise is 187.8°C.
Answer: B
NEW QUESTION # 129
A hot-water boiler has a cut-in set point of 65°C on the hot water supply temperature and a differential set point of 10°C. What is the hot-water supply temperature that causes the boiler to turn off?
Answer: A
NEW QUESTION # 130
Which of the following is NOT a renewable-energy resource?
SELECT THE CORRECT ANSWER
Answer: C
Explanation:
Renewable energy resources are naturally replenished on a human timescale. Let's evaluate each option:
A). Saw grass:
A biomass resource, renewable through regrowth.
B). Shale gas:
A fossil fuel extracted from shale formations, non-renewable.
C). Geothermal heat:
Energy from Earth's internal heat, renewable.
D). Ocean waves:
Mechanical energy from ocean surface waves, renewable.
E). Crop residue:
Organic materials from agriculture, renewable.
Conclusion:
Shale gas is not a renewable energy resource. Therefore, the correct answer is B.
NEW QUESTION # 131
......
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