energy management audit

Energy Management &

Audit

Definition of Energy Audit

“The strategy of adjusting and optimizing energy, using systems and procedures so as to reduce energy requirements per unit of output while holding constant or reducing total costs of producing the output from these systems”

“The judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions”

Types of Energy Audit

• Walk Through or Preliminary energy audit

• Detailed energy audit

• Type of energy audit chosen depends on– Function and type of industry– Depth to which final audit is

needed– Potential and magnitude of cost

reduction desired

Walk-through or preliminary audit Walk-through or preliminary audit comprises one day or half-day visit to a plant and the output is a simple report based on observation and historical data provided during the visit. The findings will be a general comment based on rule-of-thumbs, energy best practices or the manufacturer's data.

Preliminary Energy SurveyQuick overview of energy use patterns

• Provides guidance for energy accounting

system

• Provides personnel with perspectives of

processes and equipment

• Identify energy – intensive processes and

equipment

• Identify energy inefficiency ,if any

• Set the stage for detailed energy survey

Steps in conducting Preliminary Energy Audit

1. Plan how to obtain useful data– Plan how to win the involvement/ commitment of

others2. Collect data

Collect existing data e.g., a energy bills(volume/cost)

Collect Production output/records plant layouts using checklists

3. Analyse data Find unit cost of energy (Rs./ kWh for all types) Find fixed and variable energy element Derive ‘energy Index’: energy cost/unit output,

energy cost/floor area

Steps in Conducting Preliminary Energy Audit

4. Formulate plan Formulate Immediate energy-

saving actions: Where? How ? How much?

– Areas to investigate further– Resources required for more

detailed study

5. Action and Monitoring6. Next steps (e.g Need for detailed

Audit)

Detail audit Detail audit is carried out for the energy savings proposal recommended in walk-through or preliminary audit. It will provide technical solution options and economic analysis for the factory management to decide project implementation or priority. A feasibility study will be required to determine the viability of each option.

Detailed Energy Survey

Detailed evaluation of energy use pattern

• By processes and equipment

• Measurement of energy use parameters

• Review of equipment operating

characteristics

• Evaluation of efficiencies

• Identify DSM options and measures

• Recommendation for implementation

Detailed Energy Audit

• Evaluates all energy using system, equipment and include detailed energy savings and costs

• Carried out in 3 phases– Pre-audit Phase– Audit Phase – Post-Audit

Ten Steps Methodology for Detailed Audit

Step No

PLAN OF ACTION PURPOSE / RESULTS

Step 1 Step 2

Phase I –Pre Audit Phase Plan and organise Walk through Audit Informal Interview with

Energy Manager, Production / Plant Manager

Conduct of brief meeting /

awareness programme with all divisional heads and persons concerned (2-3 hrs.)

Resource planning, Establish/organize a

Energy audit team Organize Instruments & time frame Macro Data collection (suitable to type of

industry.) Familiarization of process/plant activities First hand observation & Assessment of

current level operation and practices

Building up cooperation Issue questionnaire for each department Orientation, awareness creation

Step 3 Step 4

Phase II –Audit Phase Primary data gathering,

Process Flow Diagram, & Energy Utility Diagram

Conduct survey and

monitoring

Historic data analysis, Baseline data

collection Prepare process flow charts All service utilities system diagram

(Example: Single line power distribution diagram, water, compressed air & steam distribution.

Design, operating data and schedule of operation

Annual Energy Bill and energy consumption pattern (Refer manual, log sheet, name plate, interview)

Measurements :

Motor survey, Insulation, and Lighting survey with portable instruments for collection of more and accurate data. Confirm and compare operating data with design data.

Step 5 Step6 Step 7

Step 8 Step9

Conduct of detailed trials

/experiments for selected energy guzzlers

Analysis of energy use Identification and

development of Energy Conservation (ENCON) opportunities

Cost benefit analysis Reporting & Presentation to

the Top Management

Trials/Experiments:

- 24 hours power monitoring (MD, PF, kWh etc.).

- Load variations trends in pumps, fan compressors etc. - Boiler/Efficiency trials for (4 – 8

hours) - Furnace Efficiency trials

Equipments Performance experiments etc

Energy and Material balance & energy

loss/waste analysis Identification & Consolidation ENCON

measures Conceive, develop, and refine ideas Review the previous ideas suggested by unit

personal Review the previous ideas suggested by

energy audit if any Use brainstorming and value analysis

techniques Contact vendors for new/efficient

technology Assess technical feasibility, economic

viability and prioritization of ENCON options for implementation

Select the most promising projects Prioritise by low, medium, long term

measures

Documentation, Report Presentation to the top Management.

Step10

Phase III –Post Audit phase Implementation and Follow-

up

Assist and Implement ENCON recommendation measures and Monitor the performance

Action plan, Schedule for implementation

Follow-up and periodic review

Inputs and Outputs of Energy audit

ELECTRICAL ENERGY AUDIT Areas covered under Electrical audit are1. Electrical System :• Electrical Distribution system (substation & feeders study)• PF Improvement study • Capacitor performance • Transformer optimization • Cable sizing & loss reduction • Motor loading survey • Lighting system • Electrical heating & melting furnaces• Electric ovens

2. Mechanical System : • Fans & Blowers • Exhaust & ventilation System • Pumps and pumping System • Compressed air System • Air Conditioning & Refrigeration System • Cooling Tower System

THERMAL ENERGY AUDIT

Areas covered under Electrical audit are• Steam Generation Boilers• Steam Audit and Conversation • Steam Trap Survey • Condensate Recovery System • Insulation Survey • Energy and Material Balance for Unit operation• Heat Exchanger• Waste Heat Recovery System

WATER AUDIT & CONSERVATIONIndustry has recognized 'Water Audit' as a important tool for water resource management Water Audit study is a qualitative and quantitative analysis of water consumption to identify means of reuse and recycling of water. This study includes segregation of effluent streams and schemes for effectively treating them to enable byproduct recovery. Water Audits encourage social responsibility by identifying wasteful use, enables estimation of the saving potential they not only promote water conservation but also deliver cost savings, but also companies to safeguard public health and property, improve external relations and reduce legal liability.

Benefits of energy audit

There is a lot of potential for energy savings from energy audits.. Technical solutions proposed in the energy audits show massive potential for energy savings in every sub-sector with an average of almost ten percent of the energy usage. However, this can only materialize through replication at other factories within the respective sub-sector.

Benefits of an industrial energy audit include: •Energy savings •Avoiding power factor penalties and environmental compliance costs •Quality improvements •Productivity improvements •Reduced maintenance •Fewer breakdowns •Better safety and protection •A process for repeatable improvements

Process VS. Equipment

Equipment efficiency improvement : Max. 5%

Process efficiency improvement : 15% to 30%

Conclusion

Focus on Processes

Examples of processes

• Electrical furnace

• Rolling mills

• Gas furnace

• Steam generation

• Feed water system

• Condensate return system

• Steam distribution system

• Electrlyzer

Energy intensive processes and equipment

Examples of equipment

• Electrical motor

• Pump

• Fan

• Heater (gas,..,electric)

• Dryer (steam/electric)

• Motor / generator

• Compressor

• Light bulb

Conducting Energy Audits

• Lay out – Process FD-

• Operating Conditions

General

Systems• Boiler & Steam System

•HVAC

•Elec. Supply System

•Water systems

•Compressed Air System

•Lighting

•Motors and Drives

•Processing Lines

•Building Envelope

Energy Data

•Electricity Bills

•Fuel Bills

•Water Bills

Step 1 : Data CollectionStep 2 :Pre. Audit Report

Energy Accounting

• Normalization

•Time Plotting of data

Identifying ECO

Step 3 :Facility Inspection

• Detailed Measurements

•Categorizing Consumption

•Systems Detailed Specs. And operating conditions

Step 4 :Detailed Audit Report

• Detailed Inventory

•Specific Energy Consumption

•Conceptual Design for ECO

•Economic Evaluation and Analysis

Goals of the energy audit are to :• Clearly identify types and costs of energy use

• Understand how that energy is being used and possibly wasted

• Identify and analyze more cost-effective ways of using energy

- Improved operational techniques

- New equipment

• Perform an economic analysis on those alternatives and determine which are cost-effective for your business or industry

AEE/ Certified Energy Manager CEM AEE/ Certified Energy Manager CEM ®® B - 2B - 2

Analysis of BillsThe audit must begin with a detailed analysis of the energy bills for the previous twelve months. This is important because :

• The bills show the proportionate use of each different energy source when compared to the total energy bill.

• An examination of where energy is used can point out previously unknown energy wastes, and

• The total amount spent on energy puts an obvious upper limit on the amount that can be saved.


Av. Load Duration Curve

0

200

400

600

800

1000

1200

744 1464 2208 2928 3672 4416 5136 5880 6552 7296 8016

Hrs / Year

kW

A complete analysis of the energy bills for a facility requires a detailed knowledge of the rate structures in effect for the facility.

To accurately determine the costs of operating individual pieces of equipment, break down energy bills into their components (e.g. demand charge and energy charges for the electric bill).

This breakdown also allows more accurate savings calculations for Energy Management Opportunities (EMOs) such as high-efficiency equipment, rescheduling of some on-peak electrical uses, etc.


Steps in the On-site Energy Audit

1. Identify layout and operating schedule for facility.

Make a plan or sketch of the building(s) which shows building sizes, window areas, and wall and roof composition and insulation

2. Compile an equipment inventory.

List all energy consuming equipment, with hours of

use each year and energy ratings or efficiencies


3. Determine the pattern of building use to show annual needs for heating, cooling and lighting

4. Conduct a room-by-room lighting inventory

– Light fixtures– Lamp types, size and numbers– Levels of illumination– Uses of task lighting


AEE/ Certified Energy Manager CEM AEE/ Certified Energy Manager CEM ®® B -9B -9

Energy Balance for Facility

Facility

Electricity 2,597,700 kWh

Natural Gas 329,863 GJ

Lighting 130,560 kWh

Boiler 329,863 GJ

Motors 1,516,619 kWh

Compressors 116,379 kWh

HVAC 34,286 kWh

Chillers 274,560 kWh

Electric Heaters

100,100 kWh

Miscellaneous 260,000 kWh

Total: 2,432,501 kWh/yr

AEE/ Certified Energy Manager CEM AEE/ Certified Energy Manager CEM ®® B -10B -10

Demand Balance for a Facility Electricity 345-378 kW

Lighting 18 kW

Chillers 34.3 kW

Electric Heaters 13 kW

Facility

Motors 197.1 kW

Compressors 14.9 kW

HVAC 17.1 kW

Miscellaneous 35 kW

Total: 329.4 kW

Geographic Location / Degree Days / Weather Data

• Geographic location of facility and weather data for that location are important.

• Obtain average degree days for heating and cooling for that location for the past twelve months from:

– Closest weather station, or– Local utility

• Degree-day data is very useful in analyzing energy needed to heat or cool facility.


Heating degree days (HDD) and cooling degree days

(CDD) are separate values to a particular geographic location.

The degree day concept assumes:

• The average building has a desired indoor temperature of 21.1°C,

• 2.8°C of this is supplied by internal heat sources such as lights, appliances, equipment, and people.

The base for computing degree-days is 18.33°C.


Example

Assume a period of three days when the outside temperature averaged 10°C each day

The number of HDD for this three day period would be:

HDD = (18.33°– 10°) * 3 days = 25 degree days.


Facility Layout

• Obtain the facility layout or plan; review it to determine:

– Facility size– Floor plan– Construction features

(wall and roof material, insulation levels, door and window sizes and construction)


Operating Hours

• Obtain operating hours for facility

– How many shifts does the facility run? – Is there only a single shift?– Two? Three?

Knowing the operating hours in advance gives some indication as to whether any loads could be shifted

to off-peak times.


Equipment List

• Get equipment list for facility and review it before conducting audit.

• Identify all large pieces of energy-consuming equipment such as:

– Heaters, air conditioners, water heaters, and specific process-related equipment

• Equipment list and data on operational uses of equipment provide understanding of major energy-consuming tasks or equipment at facility.


Nine Major Systems To Consider

1. Building Envelope2. HVAC System3. Electrical Supply System4. Lighting5. Boiler and Steam System6. Hot Water System7. Compressed Air System8. Motors and drives9. Special Purpose Process Equipment


As you examine each system, you should ask:

1. What function(s) does this system serve?

2. How does this system serve its function(s)?

3. What is the energy consumption of this system?

4. What are the indications that this system is probably working ?


5. If this system is not working, how can it be restored to good working condition?

6. How can the energy cost of this system be reduced?

7. How should this system be maintained?

8. Who has direct responsibility for maintaining and improving the operation and energy efficiency of this system?


Preliminary Identification of Energy Management Opportunities (EMOs)

• During the on-site audit, take notes on potential EMOs that are evident.

• In general, devote the greatest effort to analyzing and implementing the EMOs which show the greatest savings, and the least effort to those with the smallest savings potential.

• Identifying EMOs requires a good knowledge of energy efficiency technologies available to do the same job with less energy and cost.


The Energy Audit Report

• The energy audit report

– Explains the final results of the energy analyses

– Provides energy cost saving recommendations.


Energy Audit Report Format

• Executive SummaryBrief summary of recommendations and cost

savings

• IntroductionPurpose of the energy auditNeed for a continuing energy cost control program

• Facility DescriptionSize, construction, facility layout, and hours of Operation, equipment list, with specifications


• Energy Bill AnalysisUtility rate structuresTables/graphs of energy consumptions and

costsDiscussion of energy costs and energy bills

• Energy Management Opportunities (EMO’s)Listing of potential EMOsCost and savings analysisEconomic evaluation

• Energy Action PlanSchedule for implementing EMOsDesignation of an energy monitor

• ConclusionAdditional comments not otherwise covered



Emission Factors

Emissions by Fuel Type Ton CO2 Ton SO2 Ton NOx

1 ton Mazout 3.229600 0.080000 0.0040001 ton Solar 3.229600 0.040000 0.0040001 m3 of Natural Gas 0.001950 0.000000 0.0000001 kWh of Electricity (assumes emissions are from a central utility-owned power stration) 0.000775 0.000019 0.0000021 ton of LPG 3.027000 0.000000 0.000000

Drawing process flow diagram -Identification of waste streams and obvious energy wastage

Reporting Format for Energy Conservation Recommendations A: Title of Recommendation : Combine DG set cooling tower with main

cooling tower B: Description of Existing System and its operation

: Main cooling tower is operating with 30% of its capacity. The rated cooling water flow is 5000 m3/hr.Two cooling water pumps are in operation continuously with 50% of its rated capacity. A separate cooling tower is also operating for DG set operation continuously.

C: Description of Proposed system and its operation

: The DG Set cooling water flow is only 240 m3/h. By adding this flow into the main cooling tower, will eliminate the need for a separate cooling tower operation for DG set, besides improving the %loading of main cooling tower. It is suggested to stop the DG set cooling tower operation.

D: Energy Saving Calculations Capacity of main cooling tower = 5000 m3/ hr Temp across cooling tower (design) = 8 oC Present capacity = 3000 m3/hr Temperature across cooling tower(operating)

= 4 oC

% loading of main cooling tower = (3000 x 4)/(5000 x 8) = 30% Capacity of DG Set cooling tower = 240 m3/hr Temp across the tower = 5oC Heat Load (240x1000 x 1x 5)

= 1200,000 K.Cal/hr

Power drawn by the DG set cooling tower

No of pumps and its rating = 2 nos x 7.5 kW No of fans and its rating = 2 Nos x 22 kW Power consumption@ 80% load = (22 x2 +7.5 x2) x.80 = 47 kW Additional power required for main cooling tower for additional water flow of 240m3/h (66.67 l/s) with 6 kg/cm2

= (66.67 x 6) / (102 x 0.55) = 7 kW

Net Energy savings = 47 – 7 = 40 kW E: Cost Benefits Annual Energy Saving Potential = 40kWx 8400hr = 3,36,000 Units/Year Annual Cost Savings = 3,36,000 xRs.4.00 = Rs.13.4 Lakh per year Investment (Only cost of piping) = Rs 1.5Lakhs Simple Pay back Period = Less than 2 months

Energy Audit Reporting Format

Energy Audit

Reporting Format

Worksheet for energy audit and reporting

Understanding energy costs

Typical summary of energy bill by a company

Conversion to common unit of energy

Benchmarking for energy performance

• Internal Benchmarking Historical and trend analysis

• External Benchmarking Across similar industries

Scale of operation, vintage of technology, raw material specification and quality and product specification and quality

Bench Marking Energy Performance

• Quantification of fixed and variable energy consumption trends vis-à-vis production levels

• Comparison of the industry energy performance w.r.t. various production levels (capacity utilization)

• Identification of best practices (based on the external benchmarking data)

• Scope and margin available for energy consumption and cost reduction

• Basis for monitoring and target setting exercises

Benchmarking parameters•Gross production relatede.g. kWh/MT clinker or cement produced (cement plant)e.g. kWh/MT, kCal/kg, paper produced (Paper plant)e.g. kCal/kWh Power produced (Heat rate of a power plant)e.g. Million kilocals/MT Urea or Ammonia (Fertilizer plant)

•Equipment / utility relatede.g. kWh/ton of refrigeration (on Air conditioning plant)e.g. % thermal efficiency of a boiler plante.g. kWh/NM3 of compressed air generatede.g. kWh /litre in a diesel power generation plant.

Maximizing system efficiency

• Eliminate steam leakages by trap improvements

• Maximise condensate recovery• Adopt combustion controls for

maximizing combustion efficiency• Replace pumps, fans, air

compressors, refrigeration compressors, boilers, furnaces, heaters and other energy conservation equipment, wherever significant energy efficiency margins exist

Optimising Input Energy Requirement

• Shuffling of compressors to match needs.

• Periodic review of insulation thickness

• Identify potential for heat exchanger networking and process integration.

• Optimisation of transformer operation with respect to load

Fuel and Energy Substitution

Fuel substitution• Natural gas is increasingly the fuel of choice

as fuel and feedstock in the fertilizer, petrochemicals, power and sponge iron industries.

• Replacement of coal by coconut shells, rice husk,etc

• Replacement of LDO by LSHS

Energy substitution• Replacement of electric heaters by steam

heaters• Replacement of steam based hot water by

solar systems

Energy Audit

Instruments

Electrical Measuring Instruments: These are instruments for measuring major electrical parameters such as kVA, kW, PF, Hertz, kvar, Amps and Volts. In addition some of these instruments also measure harmonics. These instruments are applied on-line i.e on running motors without any need to stop the motor. Instant measurements can be taken with hand-held meters, while more advanced ones facilitates cumulative readings with print outs at specified intervals.

Combustion analyzer: This instrument has in-built chemical cells which measure various gases such as CO2, CO, NOX, SOX etc

Fuel Efficiency Monitor: This measures Oxygen and temperature of the flue gas. Calorific values of common fuels are fed into the microprocessor which calculates the combustion efficiency.

Fyrite: A hand bellow pump draws the flue gas sample into the solution inside the fyrite. A chemical reaction changes the liquid volume revealing the amount of gas. Percentage Oxygen or CO2 can be read from the scale.

Contact thermometer:

Contact thermometer: These are thermocouples which measures for example flue gas, hot air, hot water temperatures by insertion of probe into the stream. For surface temperature a leaf type probe is used with the same instrument.

Infrared Pyrometer: This is a non-contact type measurement which when directed at a heat source directly gives the temperature read out. Can be useful for measuring hot jobs in furnaces, surface temperatures etc.

Pitot Tube and manometer: Air velocity in ducts can be measured using a pitot tube and inclined manometer for further calculation of flows.

Ultrasonic flow meter: This a non contact flow measuring device using Doppler effect principle. There is a transmitter and receiver which are positioned on opposite sides of the pipe. The meter directly gives the flow. Water and other fluid flows can be easily measured with this meter.

Energy Audit

Instruments

Energy Audit

Instruments

Tachometer

Stroboscope

Speed Measurements: In any audit exercise speed measurements are critical as thay may change with frequency, belt slip and loading. A simple tachometer is a contact type instrument which can be used where direct access is possible. More sophisticated and safer ones are non contact instruments such as stroboscopes.

Leak Detectors: Ultrasonic instruments are available which can be used to detect leaks of compressed air and other gases which are normally not possible with human abilities.

Lux meters: Illumination levels are measured with a lux meter. It consists of a photo cell which senses the light output, converts to electrical impulses which are calibrated as lux.

energy management audit

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