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Energy Auditing & Demand Side Management Energy Auditing

UNIT – II2. ENERGY AUDITING

INTRODUCTION

The manufacturing industry in India, accounts for over 50% of total commercial energy used

in the country. Across the world, industry consumes about 1/3 of all natural energy sources (Murphy

& McKay, Energy Management, Butterworth Heinemann, London, 1982). The high levels of energy

used in Indian Industry compared to similar industries in advanced countries, the increasing

problems of availability of energy sources and their ever escalating costs, strongly point to the

immediate need for effective control on the use of energy.

It is believed and often proved by actual studies that a reduction in energy consumption by as

much as 10-30% is a realizable goal in a large number of industries, by better and effective energy

management at unit level. And these savings can generally be achieved with little or no additional

investment.

Any savings that can be achieved in energy costs, directly add to the profit figures. While this

is also true, in respect of other direct costs as well, i.e. labour and material costs, it is much harder

and more difficult to achieve reduction in their costs.

Another area by which profitability of an enterprise can be improved is by increasing production and

market share; but these obviously require additional investments on expansion of manufacturing

facilities and man-power and involve added management and marketing effort; and a small portion

of increased sales volume contributes to profits.

While the situation from industry to industry may vary, it may be pertinent to state that

energy cost savings to the extent of 15-20% is definitely feasible, at least in those industries (besides

commercial buildings) where serious study has not yet been attempted. One can visualize the

improvement in profitability besides improvement in the competitiveness of Indian manufactured

goods in world market, which reduction in energy costs could result in, without any major

investment.

Definition & Objectives of Energy Management

The fundamental goal of energy management is to produce goods and provide services with

the least cost and least environmental effect. The term energy management means many things to

many people. One definition of energy management is:

"The judicious and effective use of energy to maximize profits (minimize costs) and enhance

competitive positions"

(Cape Hart, Turner and Kennedy, Guide to Energy Management Fairmont press inc. 1997)

Another comprehensive definition is

P.SURESH BABU, AITS, RAJAMPET 25


"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 objective of Energy Management is to achieve and maintain optimum energy procurement and

utilization, throughout the organization and:

To minimize energy costs / waste without affecting production & quality

To minimize environmental effects.

Common Units and Measurements

SI (System International de’ units) is followed throughout this course. However, the students

are expected to be familiar with other systems of units and their conversion from one system to the

other. SI is an absolute system of units.

Fundamental units of SI system

Eight fundamental units have been defined by SI system of units and all other units are

derived from these 8 fundamental units. These are tabulated below:

S. No. Fundamental unit Unit / Dimension of Measurement

1 Length Meter, m(L)2 Mass Kilogram, kg (M)3 Time Second, s(T)4 Electric Current Ampere, A(A)5 Temperature Kelvin, K6 Luminous intensity Candela, Cd

Supplementary units7 plane angle Radian, rad8 supplementary angle Steradian, Sr

Decimal fractions and multiples

S. No. Prefix Fraction Symbol1 Milli 10-3 m2 Micro 10-6 u3 Nano 10-9 n4 Pico 10-12 p5 Femto 10-15 f6 Atto 10-18 a7 Kilo 103 K8 Mega 106 M9 Giga 109 G10 Tera 1012 T



1 Micron: 10-6m or 10-3 mm

Let us convert some of these units into other systems, which are still in use (in India and abroad).

1 inch : 1” : 2.54 mm (exactly)

1 foot : 1’ : 30.48 cm (exactly) or 0.3048 m

1 yard : 3’ : 0.9144 m

1 lb mass : 453.6 gm : 0.4536 kg

Definitions

Velocity is defined as rate of change of displacement. In SI units, velocity is represented by m/s.

Acceleration is defined as rate of change of velocity and is represented by m/s2. Acceleration due to

gravity is expressed by g and is generally taken as 9.81 m/s2.

Force is defined by Newton’s second law of motion and is denoted by ‘Newton’. 1 Newton is the

force that is required to bring 1 unit of acceleration (1 m/s2) in a unit mass (1 kg).

F : ma (kg*m/s2) : measure in Newton

Work is defined as force acting over a distance.

W : F*s (kg.m/s2)*m : Newton-m : kg.m2/s2

Energy and Work have the same units, i.e. Newton-m, which is also called joule. 1 erg is the unit of

energy in CGS system of units.

1 erg : 10-5

Power is defined as rate of work done and is expressed in watts.

P : W/T (kg.m/s2.s) : Newton – m/s2 or joule/s or watt (W)

According to First law of thermodynamics, work and heat are mutually convertible.

2.1. ENERGY AUDIT

The main purpose energy audit is to increase energy efficiency, and reduce energy related

costs. Energy audit is not an exact science. It involves collection of detailed data and its analyses.

More often sophisticated instruments are used to collect data, but its analyses and interpretation

requires technical knowledge, experience, and sound judgment.

Energy audit is a fundamental part of an Energy Management Programme (EMP) in

controlling energy costs. It will identify areas of wasteful and inefficient use of energy.

As per the Energy Conservation Act, 2001, Energy Audit is defined as "the verification,

monitoring and analysis of use of energy including submission of technical report containing

recommendations for improving energy efficiency with cost benefit analysis and an action plan to

reduce energy consumption".



2.2. DEFINITIONS AND CONCEPTS

The successful implementation of individual energy conservation programme depends on a

proper organizational framework and baseline data for identifying and evaluating energy

conservation opportunities. The determination of the baseline data requires a comprehensive and

detailed survey of energy uses, material-energy balances, and energy loss. This survey is generally

referred to as the Energy Audit.

To save energy, it is necessary to know where, how and how much energy is being

consumed. The objective of energy audits is to characterize and quantify the use of energy within the

plant at various levels in departments, sections, major processes, and major equipment. The plant

energy study provides a comprehensive and detailed picture not only of the type and quantity of

energy being used but also how efficiently it is being utilized, and where it is wasted or lost.

The energy audit process include description of energy inputs and product outputs by major

departments or by major processing functions, and will evaluate the energy; efficiency of each step

of the manufacturing process. Means of improving these will be listed, and a preliminary assessment

of the cost of these improvements will be made to indicate the expected payback on any capital

investment needed.

The aims of energy audit are as follows:

1. To identify the main energy users and quantify their annual energy consumption.

2. To ascertain the optimized energy data

3. To determine the availability or energy/production data

4. To investigate the distribution systems for the site services and note any existing metering

5. To prepare energy and process flow diagrams for the site

The Energy Audits are normally carried out in two phases, i.e., Preliminary Energy Audit (PEA) and

Detailed Energy Audit (DEA).

2.3. TYPES OF PLANT ENERGY STUDIES

The type of Energy Audit to be performed depends on:

Function and type of industry

Depth to which final audit is needed, and

Potential and magnitude of cost reduction desired

There are mainly two types of energy audit, viz.

1) Preliminary Energy Audit (PEA)

2) Detailed Energy Audit (DEA)



2.3.1. Preliminary Energy Audit (PEA) / House Keeping Practices

Considerable savings are possible through small improvements in the “house keeping”

practices, and the cumulative effect of many such small efficiency improvements could be quite

significant. These can identify by a short survey, observation and measurements. Many energy

conscious industries have already achieved considerable progress in this area.

Approach to Preliminary Energy Audit (PEA)

This essentially involves preliminary data collection and analyses. The PEA is based on

collection of available data, analysis, observation, and inference based on experience and judgment is

carried out within a short time.

The PEA is the first step in implementing an energy conservation programme, and consists of

essentially collecting and analyzing data without the use of sophisticated instruments. The ability and

experience on the part of Energy Auditor will influence the degree of its success.

Normally the results of the audit would depend on :-

Experience of the auditor Availability and completeness of data

Physical size of the facility Depth of analysis of available data

Complexity of operations within the facility Awareness of energy matters within the facility

Broadly, the audit is carried out in six steps:-

1. Organize resources

Manpower / time frame

Instrumentation

2. Identify data requirements

Data forms

3. Collect data

a. Conduct informal interviews

Senior management

Energy manager/coordinator

Plant engineer

Operators and production management and personnel

Administrative personnel

Financial manager

b. Conduct plant walkthrough/visual inspection

Material/energy flow through plant

Major functional departments

Any installed instrumentation, including utility meters

Energy report procedures



Production and operational reporting procedures

Conservation opportunities

4. Analyze data

a. Develop data base

Historical data for all energy suppliers

Time frame basis

Other related data

Process flow sheets

Energy consuming equipment inventory

b. Evaluate data

Energy use consumption, cost, and schedules

Energy consumption indices

Plant operations

Energy savings potential

Plant energy management program

Preliminary energy audit

5. Develop action plan

Conservation opportunities for immediate implementation

Projects for further study

Resources for detailed energy audit

Systems for test

Instrumentation; portable and fixed

Manpower requirements

Time frame

Refinement of corporate energy management programme

6. Implementation

Implement identified low cost/no cost projects

Perform detailed audit

The preliminary energy audit is essentially, as the name implies a preliminary data collection

and its analysis process. Readily available data on the plants energy systems and energy-using

processes or equipment are obtained and studied. The operation and condition of equipment are

observed by going around the plant. These provide basis to develop recommendations for immediate

short term measures and to provide quick and rough estimates of savings that are possible and

achievable.

A preliminary study usually identifies and assesses obvious areas for energy savings such as

stream leaks, compressed air leaks, poor or missing insulation, condensate recovery, idling



equipment, deterioration and deficiencies in combustion and heat transfer equipment etc. and serves

to identify specific areas for the detailed plant energy study.

2.3.1.1. Preliminary Energy Audit Methodology

Preliminary energy audit is a relatively quick exercise to:

Establish energy consumption in the organization

Estimate the scope for saving

Identify the most likely (and the easiest areas for attention

Identify immediate (especially no-/low-cost) improvements/savings

Set a 'reference point'

Identify areas for more detailed study/measurement

Preliminary energy audit uses existing, or easily obtained data

2.3.2. Detailed Energy Audit (DEA)

This would be a comprehensive energy efficiency study using portable energy monitoring

instruments. The essential part of this audit is carrying out various measurements and analyses

covering individually every significant energy consuming plant item/processes, to determine their

efficiencies and loss of energy at that point, and potential energy savings are explored and

crystallized, and every recommendation for investment is supported by criteria such as pay-back

analysis.

The detailed plant energy study is a comprehensive analyses evaluation of all aspects of

energy generation, distribution and utilization within the plant. At the plant level, the analyses

require time series data on a daily, monthly, or yearly basis, on the quantities of all forms of primary

energy flowing into the plant, e.g. coal, fuel oil, electricity, etc. and production figures of major

products, by-products and waste products, at the department or section level. Information is required

on the quantity of energy forms consumed, and the production figures of intermediate products. At

the equipment level, in addition to the quantities of energy forms and material products, process

parameters such as temperature, pressure, flow rate, etc. are also required.

Data generation and collection is an essential and critical element of a detailed energy audit

study. Difficulties in getting data required generally arise due to unavailability of historical records.

The acquisition of actual operating data through existing or new permanently installed instruments or

portable test instruments cannot be overemphasized in this context.



Ten steps methodology for DEA

STEP No PLAN OF ACTION PURPOSE / RESULTS

Step-1Phase-I: Pre Phase Audit Plan and Organize Walk through Audit Informal Interview with

Energy Manager, Production / Plant Manager

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.Step-2 Conduct of brief meeting /

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

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

Step-3Phase-II: Audit Phase Primary data gathering,

Process Flow Diagram, & Energy Utility Diagram

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)

Step-4 Conduct survey and monitoring

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 Conduct of detailed trials / experiments for selected energy guzzlers

Trials/Experiments:o 24hours power monitoring (MD, PF, kWh

etc.).o Load variations trends in pumps, fan

compressors etc.o Boiler/Efficiency trials for (4-8 hours)o Furnace Efficiency trials Equipments

Performance experiments etc.,Step-6 Analysis of energy use Energy and Material balance & energy

loss/waste analysis.Step-7 Identification and

development of Energy Conservation (ENCON) opportunities.

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.

Step-8 Cost benefit analysis Assess technical feasibility, economic viability and prioritization of ENCON (Energy Conservation) options for implementation.

Step-9 Reporting & Presentation to the Top Management

Documentation, Report Presentation to the top Management.

Step-10Phase-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

The duration of DEA studies depends on plant size and complexity. Whereas the preliminary

energy study can be carried out in a few days, the detailed study would require anywhere from few

weeks to months to years of effort.

Plant energy studies can be carried out in house if adequate resources and expertise exist for doing

so. Alternatively or additionally, external assistance may be sought from energy consultants,

equipment suppliers, and engineering and design firms, in either case, intense interaction between

plant personnel and the study team is essential for a proper understanding and a meaningful analysis

of the plants energy options. Too often, the plant energy study is considered to be the consultants

problem, resulting in minimal inputs and involvement from plant personnel. This attitude is counter-

productive. Without the active participation of all levels, full benefits cannot be expected to be

accomplished.

2.4. ENERGY CONSUMPTION MONITORING

Energy Consumption is to monitor, assess by a company/industry and compared with a

specific products manufactured by the industry can be done by two parameters as follows.

They are,

1. Energy Index

2. Cost Index

2.4.1. Energy index

Energy index is a useful parameter to “monitor and compare energy consumption of specific

products manufactured by the industry”.



Energy index is the figure obtained by dividing energy consumption by production output,

and the index may be calculated weekly, monthly or annually. Although the total energy indices are

sufficient for monitoring purposes, a record of the individual energy indices should be maintained. In

the event of an increase or decrease (due to perhaps a conservation measure) in energy index, the

particular source can be investigated immediately.

Energy Index (EI )= total energy consumptiontotal production output

(based on weekly, monthly & annually)

Energy may be purchased in various units, for example, coal in tons; gas in ft 3,m3, therms; oil

in gallons, litres, tons, barrels etc. the relevant conversion units from one system to the other are

given below:

To determine the heat available from the fuel, it is necessary to know the calorific value per

unit quantity of energy form and this data is also given in the following example. Further, when

estimating the total energy used by a company that consumes several energy forms, it is convenient

to rationalize the heat units to common basis.

Example 1:

An office block uses 40*103 gallons of fuel oil per year for heating purposes. The calorific value is

175*103 Btu/gal. The fuel consumption may be expressed in litres or m3.

Sol:

40*103*4.545 litres = 182*103 litres = 182 m3

The calorific value may be quoted as 103 J/litres

175*103 Btu/gal = 175*103*0.2321*103 J/l = 40600*103 J/l = 40.6*106 J/l

The total theoretical heat available becomes:

i. 40*103 gal *175*103 Btu/gal = 7.00*109 Btu/year

ii. 182*103 I * 40600 *103 Btu/gal = 7.39*109 J/year

iii. 182 m3 *40.6*106 Btu/gal = 7.39*109 J/year

Example 2:

Consider a company using three energy forms – oil, gas and electricity. The annual energy

consumption is shown below in various energy units. Each of these energy types may be represented

as a percentage of the total energy used and tabulated as an energy balance.

Energy type Consumption Energy Energy (J) Energy (Wh)

Oil 10*103 gal 1.775*109 Btu 1.872*1012 0.520*109

Gas 5*103 therms 5*103 therms 0.526*1012 0.146*109

Electricity 995103 kWh 995103 kWh 0.358*1012 0.995*109



Total 2.754*1012 1.661*109

Note: Calorific value of oil: 18.3*10 Btu/lb; Density of fuel: 9.7 lb/gal



Percentage Energy Balance

Energy form Percentage

Oil 67.9

Gas 19.1

Electricity 13.0

Total 100.0

Example 3:

If the company in Example 2 produces 100*103 tons of a particular product, calculate the energy

indices.

Sol:

Oil energy index : 0.520*109 Wh/100*109 = 5.20*103 Wh/ton of product

Gas energy index : 0.146*109 Wh/100*109 = 1.46*103 Wh/ton of product

Electricity energy index : 0.995*109 Wh/100*109 = 9.95 103 Wh/ton of product

Total energy index : 0.661*109 Wh/100*109 = 16.61*103 Wh/ton of product

2.4.2. Cost Index

The cost index is another parameter which can be used to “monitor and assess energy

consumption by a company”. The cost index is defined as the cost of energy divided by the

production output. An individual cost index can be determined for each energy form and for the total

energy consumption by the company.

Cost Index (CI )= total cost of energytotal production output

Example 4:

Table below shows energy costs for a company using coke, gas and electricity. This company

produces 15*103 tons per year. Calculate cost indices.

Energy type Consumption Costs (Rs.)

Coke 1.5*103 (tons) 108.0*103

Gas 18*103 (therms) 3.6*103

Electricity 1*109 (Wh) 22.5*103

Total 134*103

Sol:

Coke cost index = 108.0*103 / 15*103 (tons) = Rs. 7.2/ton

Gas cost index = 3.6*103 / 15*103 (tons) = Rs. 0.2/ton



Electricity cost index = 22.5*103 / 15*103 (tons) = Rs. 1.5/ton

Total cost index = 134.1*103 / 15*103 (tons) = Rs. 8.9/ton

2.5. REPRESENTATION OF CONSUMPTION

Several methods of representing energy flows and energy consumption are available and

these may be graphical or tabular. Most among them are the “pie chart and the sankey diagram”.

2.5.1. Pie chart

Energy usage is plotted on a circular chart where the quantity of a particular type is

represented as a segment of a circle. The size of the segment will be proportional to the energy

consumption using a particular fuel (energy form or source) relative to total energy use. The energy

units must be rationalized to the same units.

Example 5:

A company uses on an hourly basis 11.72*103 therms of gas, 500*103 W electricity and 4.32*109 J

oil. Represent these energy consumptions in a pie chart.

Sol:

The results may all be expressed in watts as follows:

Gas = 11.72*103 / 29.31*10-3 = 400*103 W

Electricity = 500*103 W

Oil = 4 .32*109*0.278*10-3 = 1200*103 W

Total hourly energy consumption = 2100* 103 W

The pie chart can be represented as follows

Gas68

Oil206

Electricity86

Energy Consumption

Gas Oil Electricity

Consequently, the angles occupied by the segment are:



Gas = (400*103/2100*103)*360 = 680

Oil = (1200*103/2100*103)*360 = 2060

Gas = (500*103/2100*103)*360 = 860

Example 6:

The use of pie charts may be extended to show the consumption of a particular type of energy

through a company. Consider electricity usage by a company as:

Office heating 150x103W (1000)

Lighting 120x103W ( 800 )

Boiler house 90x103W ( 600 )

Process 180x103W (1200)-------------- --------

Total 540 x103W (3600)

The pie chart can be plotted as follows

Office heating

100

Lighting80Boiler house

60

Process120

Energy Consumption

Office heating LightingBoiler house Process

2.5.2. Sankey diagram

Following Figure shows a Sankey diagram which represents all the primary energy flows into

a factory. The widths of the bands are directly proportional to energy production (source), utilization

and losses. The primary energy sources are gas, electricity and coal/oil (say, for steam generation)

and represent energy inputs at the left-hand side of the Sankey diagram.

Sankey diagrams are quite difficult to construct as measurements must be made for all

energy flows and this will involve considerable metering and instrumentation. However, the picture

can be gradually built up starting from gas and electricity before going on to steam. The construction

of a Sankey diagram is an excellent exercise in energy management and its value is in highlighting


Lighting (150)

Boilers (200)

Powerhouse (150)

Officeheating (200)

SteamLosses (630)

HeatingLosses (650)

PowerhouseLosses (170)

Gas(700)

Process B(500)

Process A(1700)

Oil(3850)

Electricity(500)

Steam

BoilerLosses (700)

Energy Inputs: Oil, Gas, Electricity are represented in left side

Sankey diagram representing energy usage (106 Joule per hour) by a company


losses which one never knew existed.

For the purpose of monitoring and checking energy consumption and usage on a weekly or

monthly basis, pie charts and Sankey diagram are relatively difficult. An alternative method of

monitoring energy consumption on a time-dependent basis is to use load profiles.

2.6. LOAD PROFILES (HISTOGRAM)

The usages of oil, gas and electricity in a plant can be plotted on a graph as shown in

following Figure. The results illustrate seasonal variations and perhaps variations in production

schedules. This technique has the major advantage that after a period of time, energy consumption

patterns emerge and it is possible to tell at a glance if an area is exceeding its predicted value. An

overall load profile equivalent to several pie charts and sankey diagrams can be obtained by plotting

the previous profiles can be also drawn.

Load factor — The ratio of the average load over the peak load. Peak load is normally the maximum

demand but may be the instantaneous peak. The load factor is between zero and one. A load factor

close to 1.0 indicates that the load runs almost constantly. A low load factor indicates a more widely

varying load. From the utility point of view, it is better to have high load-factor loads. Load factor is

normally found from the total energy used kilowatt-hours.



Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

100

200

300

400

500

600

700

Monthly Load Profile (kw) for electricity usage


50

100

150

200

250

300

350

Monthly Load Profile (kw) for gas usage


100

200

300

400

500

600

700

Monthly Load Profile (103 kw) for oil usage



2.7. ENERGY CONSERVATION SCHEMES

Development of an energy conservation programme can provide savings by reduced energy

use. However, it is economical to implement an energy conservation program only when savings can

offset implementation cost over a period of time. Potential areas of conserving energy and a logical

analysis of the methods or techniques of conservation would provide a systematic and disciplined

approach to the entire conservation strategy as a sequel to the energy audit. Some established

conservation trends are replacement, retrofit, process innovation, fuel conversion and co-generation.

It is generally considered that investment for energy conservation should be judged by

exactly the same criteria as for any other form of capital investment. Energy conservation measures

may be classified on an economic basis and fall into the following three categories:

1) Short term: These measures usually involve changes in operating practices resulting in little

or no capital expenditure.

2) Medium term: Low-cost modifications and improvements to existing equipment where the

pay-back period is less than two years and often under one year.

3) Long term: Modifications involving high capital costs and which frequently involve the

implementation of new techniques and new technologies.

While the first two categories together can achieve savings of the order of 5-10%, capital

expenditure using existing and new technology may achieve a further 10-15%. It is impossible to

give a comprehensive list of all items in each category but selected examples are given for each

section.

Short-term energy conservation schemes

Items in this group can be considered as a tightening of operational control and improved

housekeeping.

a. Furnace efficiencies: greater emphasis should be placed on minimum excess combustion air.

Oxygen levels of flue gases should be continually monitored and compared with target

values. Oil burners must be cleaned and maintained regularly.

b. Heat exchangers: in the case of heat exchangers where useful heat is transferred form product

streams to feed streams, careful monitoring of performance should be carried out to

determine optimum cleaning cycles. Frequency of cleaning will generally increase as a result,

with consequent improved heat recovery.

c. Good housekeeping: doors and windows should be kept closed as much as possible during the

heating season. Wear natural light is sufficient, do not use artificial light. Avoid excessive

ventilation during the heating season. Encourage staff to wear clothing appropriate to the

temperature of the working areas.



d. Use of steam: major steam leaks should be repaired as soon as possible after they occur: often

a firm specializing in ‘on stream’ maintenance can be used. One crude distillation columns

where live steam is used for stripping purposes, the amount required should be optimized and

carefully controlled.

e. Electrical power: in industries where all the electrical power is ‘imported’, conservation

measures can reduce the annual electricity costs by 10-15%. Steam driven turbines may prove

more economical as prime movers. Natural air cooling may be sufficient and therefore

induced-draught fans may be taken out of commission. Pumping costs can sometimes be

saved by utilizing gravity to move products from one tank to another. Where possible, use

off-peak electricity.

Medium-term energy conservation schemes

Significant savings in energy consumption are often available for quite modest outlays of

capital based on a pay-back period of less than two years.

a. Insulation: Improving insulation to prevent cold air leaking into the building and also,

improving insulation of the steam distribution system. Many optimum insulation thicknesses

were determined at a time when fuel oil was £6 per tone and, consequently, at present fuel oil

prices, optimum thicknesses have increased appreciable. In addition, in older plants lagging

may have deteriorated to varying degrees.

In one company, additional insulation was added to four boiler casing after

calculation had showed the structures could accept the increase in temperature. For an outlay

of £25000, savings of £60000 per annum were achieved.

In an oil refinery the lagging on the process steam system was up rated to new

optimum thicknesses and the £20000 invested in the project was recouped within a year.

b. Heating systems: Improving the time and temperature control of the heating systems in

buildings should result in substantial energy savings.

c. Replacing air compressors

d. Instrumentation: to measure and control the energy conservation parameters, adequate

instrumentation must be provided or operators will soon lose interest in maintaining

efficiencies if they are working with inadequate and unreliable instruments.

e. Process modifications: Many of these schemes will depend on the nature of the industry

concerned, however, one general scheme will be considered. Steam condensate, if

uncontaminated, may be used as boiler feed water. Improved condensate return systems can

increase the amount recovered. The effect will be to increase the heat recovered in the

condensate and at the same time reduce raw water and treatment costs.

In one instance 10000 kg h-1 of condensate was recovered for an investment of

£10000; the pay-back time was less than six months.



f. Burners: the control and amount of atomizing steam is important and often in furnaces and

boilers the amount of atomizing steam is far in excess of design.

In a hospital two fuel oil-fired boilers were examined and in some instances it was found that

1 kg steam/kg fuel oil was being utilized. The oil burners were replaced and the atomizing

steam requirements are now 0.1 kg steam/kg fuel oil. The pay-back for an outlay of £12000

was ten months.

g. Electrical Power Savings: considerable savings may be made by adjusting the electrical

power factor correction.

Capacitors were installed in one particular company at a cost of £10000. The power factor

was increased from 0.84 to 0.97 reducing the maximum demand level by over 14 per cent.

The pay-back time was nine months.

To increase plant capacity two feed pumps may be run in parallel to achieve the required feed rate.

When replacement, for mechanical reasons, becomes necessary it is more economical to replace the

pumps by a single pump having a higher capacity.

Long-term energy conservation schemes

To obtain further economics in energy consumption required the spending of significant

amounts of capital, although, in many cases, the return on capital for the long-term investment may

not be as good as that of the medium term. Full financial evaluation is needed, using the appraisal

techniques discussed in unit-V, to ensure that investment is economically viable.

a. Heater modifications: the installation of heating tubes and air pre-heaters to extract more heat

from furnace flue gases.

b. Improved Insulation: Additional lagging of heated storage tanks. This type of project often

comes within the medium-term group.

c. Heat recovery: Improved heat recovery in the processing areas by additional heat exchange

schemes.

Many of the energy projects that have been outlined may be adopted by a wide variety of companies.

However, some are more specific in their application and it is necessary to consider the contribution

of energy costs to companies and energy usage by different industries.

2.8. MEASUREMENTS IN ENERGY AUDIT

Measurements are critical in any serious effort to conserve energy. Apart from helping to

quantify energy consumption, measurements also provide a means to monitor equipment

performance and check equipment condition. Examples of measurements and instrument types are:



1. Flow/Velocity: Orifice plate, picot tube, Ventura tube, turbine meter, vortex shedding flow

meter, ultrasonic flow meter.

2. Temperature: Thermometers – Bimetallic, Resistance etc., Thermocouple, Radiation

pyrometer.

3. Pressure: Bourdon gauge, Diaphragm gauge, manometers

4. Stack Gas Analysis: Orsat apparatus, Oxygen analyzers, carbon dioxide analyzers, Carbon

monoxide analyzers.

5. Heat Flow: Thermograph equipment

6. Electrical: Multi-meter, Ammeter, Wattmeter, Power Factor meter, Light meter

7. Stream Trap Testing: Stethoscope, Ultrasonic Detector

Analyses, evaluation and interpretation of data lead to identification of various measures that

would save energy. These measures are then evaluated with regard to their technical and economic

feasibility resulting in recommendations for further action

2.8.1. Electrical Measuring Instruments

These are instruments for measuring major

electrical parameters such as kVA, kW, PF, Hertz,

VAr, 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.

Ammeter: it measures the current absorbed by

appliances and motors.

Voltmeter: it measures the voltage or voltage drop in the grid or electrical circuits.

Watt-meter: it measures instant power demand of appliances/motors or the power performance of

generators.

Cos-meter: it measures the power factor or monitors the rectification devices.

Multi-meter: it measures all the above quantities.

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.

All the above instruments are usually portable. They are connected to the wiring with the use

of nippers and they could feature a data-logger. Measurements of electrical power and energy

consumption should be made on all energy intensive areas and installations. Since these instruments



are generally not expensive, it is advised to examine their permanent installation in some of the

above cases.

During the measurement of all the above quantities, a strict distinction must be made between the

total power (metered in kVA) and the active power (usually metered in kW), as well as of Cos.

Care is also needed with electrical loads that are not expected to present a sinusoidal waveform, as is

the case with variable speed motors and UPS. Usual measuring instrumentation is based on a

sinusoidal waveform, which gives wrong readings. In such cases, the use of meters measuring real

RMS (Root Mean Square) values is necessary. The function of such meters is based on digital

sampling, so they could be substituted with PC-based meters.

2.8.2. Temperature measurement

PC-based temperature meters are already available in respective shops. The most usual

measuring technologies include:

a) Resistance Thermometer Detectors (RTD):

From the most technologically advanced instruments. They feature internal signals for

calibration and resetting. They are very accurate and are used as permanent instruments in M&A

applications.

b) Thermocouples:

They are widely used and are not expensive. They cover a wide range of temperatures, from a

few degrees up to 1000oC and are usually portable. They need frequent calibration with specialized

instruments. Their main disadvantage is that they have a weak signal, easily affected by industrial

noise.

c) Thermistors:

They are used as permanent meters and are of low cost. They are characterized by a strong,

linear in variation with temperature signal and have an automatic resetting capability. Still this type

and the thermocouple are not usually found in M&V (Measuring & Verification) set-ups.

d) Infrared thermometers:

They measure temperatures from a distance by sensing the bodies’ thermal

radiation. They sense «hot-spots» and insulation problem areas. Portable

and easy to use but with limited accuracy; they also require the knowledge

of the emissivity coefficient.

This is a non-contact type measurement which when directed at a heat

source directly gives the temperature read out. This instrument is useful for

measuring hot spots in furnaces, surface temperatures etc.



2.8.3. Flow measurements

To estimate heat flow through a fluid, it is necessary to measure its flux (mass or volume).

Such measurements typically include air and liquid fuel, steam and hot/cold water or airflow

measurements. Combined with heat measurement, they provide an estimation of heat supply.

Installation of fuel flow meters is compulsory for all large boilers and furnaces. It is also

recommended on steam networks and on hot water installations, used in process and boiler rooms.

Combining a measurement of temperature difference with flow measurement, allows for the

measurement of the thermal and energy flows.

The meter should be carefully selected, taking into account the fluid type, any diluted and

corrosive substances, the speed range and the relevant costs. Flow-metering sensors can be classified

as follows:

Differential pressure meters (of perforated diaphragm, Venturi or Pitot tube type)

Interference meters (of variable cross section, positive shift, eddy or vortex metering type)

Non-interference meters (of ultrasonic or magnetic meter type)

Mass meters (of Coriolis or angular momentum type)

From the above flow meters, the portable ones are usually the Pitot tube and non-interference

meters. Pitot tubes are usually accompanied with an electric manometer for speed measurement.

Ultrasonic meters technology has also progressed, offering accuracy close to 1-2%. They require

relatively pure fluids and are easy to use. They are installed simply with the use of nippers on the

measured tubing.

The most usual meters for permanent heat flow measurements are the eddy type or vortex-meters.

Additionally, hot wire anemometer type instruments are used, either as portable or permanent meters.

During fluid flow measurements, the instructions of the instrument’s manufacturer must be closely

followed. Attention should also be paid, to calibrate the meters frequently, as their calibration is most

difficult.

2.9. PRESENTATION OF ENERGY AUDIT REPORT

Each report should include:

1. Title Page

Report title

Client name (company for which facility has been audited)

Location of the facility

Date of Report

Audit contractor name

2. Table of Contents



3. Executive Summary

All information in the Executive Summary should be drawn from the more detailed

information in the full report. The Executive Summary should contain a brief description of

the audit including:

Name, plant(s), location(s) and industry of the company audited

Scope of the audit

Date the audit took place

Summary of baseline energy consumption presented in table form. Baseline

energy

consumption refers to the energy used annually by the facility/system

audited.

Results:

- Assessment of energy-consuming systems

- Identification of EMOs and the estimated energy, greenhouse gas

(GHG), and cost savings associated with each option along with the

related cost of implementing the measures and the expected payback

period. This material should be presented in table form. In the event

that an audit covers more than one facility, the statistics for each

facility should be reported on an individual basis to the extent

possible.

Recommendations summarized in table form.

4. Introduction

The Introduction should include:

Audit Objectives: a clear statement that defines the scope of the energy

audit in clear and measurable terms - example, space(s), systems and/or

process(es) to be audited

Background Information: a description of the location of the facility where

the audit will be conducted, as well as information regarding facility layout,

products/services produced/distributed, operating hours including seasonal

variations, number of employees and relevant results of previous energy

initiatives.

5. Audit Activity and Results

This section should make reference to:

Description of the audit methodology (techniques - e.g. inspection,

measurements, calculations, analyses and assumptions)

Observations on the general condition of the facility and equipment



Identification / verification of an energy consumption baseline in terms of

energy types, units, costs and greenhouse gas (GHG) emissions for the

facility/system being assessed

Results of the audit including identification of EMOs and the estimated

energy, GHG, and cost savings associated with each measure as well as the

required investment and payback period associated with each of the EMOs

identified.

6. Recommendations

This section should list and describe the recommendations that flow from the

identification of EMOs and may include details concerning implementation. An

explanation should be provided for recommending or not recommending each EMO

identified in the results.

7. Appendices

Appendices include background material that is essential for understanding the

calculations and recommendations and may include:

Facility layout diagrams

Process diagrams

Reference graphs used in calculations, such as motor efficiency curves

Data sets that are large enough to clutter the text of the report.

General Points on Report Writing

Grammar and Style: The report should be grammatically correct. The language should be clear,

concise and understandable by all readers. The writer should avoid jargon.

Documentation: All numbers related to the results should be supported by information indicating

how they were derived. This includes all savings, investment and payback information.

Mathematical Accuracy: All calculations should be checked for mathematical accuracy. Where, for

example, a table showing the breakdown and total of energy use or costs is included in the report, the

total of the numbers in the breakdown should equal the amount shown as the total. If, for some

reason, this is not the case, there should be a note explaining why the discrepancy is appropriate.

Similarly, if numbers used in the full report differ from corresponding numbers shown in the

Executive Summary, the report should contain a note or notes explaining why the discrepancy is

appropriate.

Logical Consistency: The results should be logically consistent. For example, separate summaries in

the report may use different bases for calculating energy savings. One summary might be based on

energy savings related to the recommended measures while a second summary might be based on

energy savings related to both recommended and non-recommended measures. If such a logical


Baseline Energy Use and CostAuditedFacility/SystemDescription

Electricity Natural Gas Other (Specify) TotalCost

Units(kWh/yr)

Cost(Rs.)

Units(m3/Yr)

Cost(Rs.)

Units Cost(Rs.) (Rs.)

TOTAL

RecommendationsRec. # Description Potential

ElectricitySavings(kWh/yr)

PotentialNaturalGasSavings(m3/Yr)

Otherpotentialenergysavings(specifytype andunits

Potentialsavings(Rs./yr.)

Cost toimplement(Rs.)

SimplePayback(Yrs.)

TOTAL


inconsistency is considered necessary by the auditor, it should be explained in a note and in the

example above, both tables should be referenced to the note.

Illustrations: Graphs and charts may be used to spark interest in the report and implementation of

the recommendations but should not be used as a substitute for numerical data.

Tables for the Executive Summary



Summary (***Following is not in syllabus***)

The ABCs of Energy conservation schemes can be used as a checklist to identify the areas of

deficiency and adopt the right approach for energy savings.

A B C

Adjustable frequency drives

Ambient air reset controls

Analysis of audit results

Balancing energy

Blow-down controllers

Break-even analysis

Co-generation

Chiller efficiency optimization

Copper fins in cooling /heating

D E F

Demand control

Delay monitoring and

avoidance

DDC management systems

Economizer controls

Efficient equipment

selection

Energy audit and analysis

Fenestration techniques

Filter loading control

Fan efficiency optimisation

G H I

Glazing systems for heat gain

Gas cooling

General housekeeping

Heat energy tracking

Heat recovery methods

High efficiency criteria

Insulation

Infiltration control

inspections

J K L

Job-task analysis

Joint sealing and testing

Justify retrofits

Kettle heat control

kWh and kW reduction

keg temperature control

Lighting

Load calculation/shedding

Life-cycle cost analysis

M N O

Maintenance

Metering

Monitoring

Non conventional methods

Novel technologies

Natural gas use

Occupancy sensors

Optimization

Over-rating avoidance

P Q R

Peak demand shaving

Power factor corrections

Pay-back period

Quality

Retrofits

Return air systems

Rate of return

S T U

Solar energy

Steam traps

Selection criteria

Time of day

Thermostat settings

Temperature control

U-values

Utilities

Utility meter close to site

V W XYZ

Variable air volume boxes

Variable supply air set point

Water conservation

Waste heat recovery

XTMR losses

Yearly cost and savings



Voltage selection Water treatment Zone controls

In addition to these basic checklists, the sections below deal with individual equipment to serve as a

quick and handy reference, aimed primarily at shop floor personnel.

Burners

1. Right burner nozzle for given turndown ratio

2. No vapor or gases present before light up

3. Establish air supply before oil supply

4. Drain cold air before start up

5. Correct oil temperature at burner tip

6. Correct air pressure for LAP burners

7. Check oil leaks near burner

8. Flame centering with no impingement

9. Adjust flame length

10. Adjust burners and damper for 13% carbon dioxide and brown smoke.

11. Close oil line before shutting off air blower.

Boilers and Steam – Generation, Distribution & Utilization

Generation:

1. Proper selection of burners and stokers.

2. Correct temperature and pressure of fuel oil at burner tip

3. Reduce radiation losses by improved thermal insulation

4. Blow down and water process heat to preheat the boiler feed water

5. Critical scrutiny of steam and power within boiler house

6. Provision and maintenance of meters

7. Analyze flue gases for optimum gas levels

8. Uniform thickness of coal bed without segregation.

9. Waste heat recovery for heating feed water or combustion air

10. Schedule process operations to avoid fluctuations in boiler loads

11. Avoid excessive blow downs

12. Avoid air infiltration and gas ex-filtration.

13. Prevent excessive scale formation on heat transfer surfaces

14. Adjust speed, feed and air supply to stabilize flame

15. Reduce un burnt ash in coal-firing and ensure adequate soot blowing

16. Prevent flame from impinging upon surface.

Distribution:

1. Size pipelines for maximum expected loads, and avoid circuitous pipelines



2. Replace sharp elbows with long radius bends and Ts with smooth Y’s

3. Slope pipes towards receiving end with provision for condensate removal

4. Rectify pipe sag periodically and isolate steam lines not in use.

Utilization:

1. Keep pressure as low as possible

2. Lag and water proof all piping and valves

3. Inspect main valves and traps for leaks

4. Avoid backpressure on steam traps

5. Ensure air removal from heated process vessels

6. Maintain process steam dry and saturated

7. Keep heat exchanger surfaces clean.

Condensate Recovery:

1. Avoid group trapping and design traps for startup loads

2. Drain contaminated condensate insulate all condensate-return lines

3. Investigate feasibility of flash steam recovery for high pressures

4. Provide instrumentation to prevent over flows from collecting tanks

Electrical Systems:

Sub-Stations and Transformers:

1. Locate sub-station near load centre

2. Identify under loaded transformers and redistribute load

3. Operate identical transformers in parallel whenever required

4. Switch off idle transformers in cyclic rotation on primary

5. Switch off transformers and re-adjust load on holidays and power cuts

6. Use transformers with lower losses

7. Provide circuit breakers and dis-connectors to transformers

8. Adopt split bus system to allow flexibility of operation

9. Provide instruments for monitoring performance of individual transformers

10. Provide a separate lighting transformer

11. Monitor tap positions of distribution transformers and re-adjust as required

12. Select power transformers with OLTC and auto control

13. Load bus bar parallel paths in the sub stations equitably.

Load management and power factor improvement:

1. Incorporate maximum demand alarm

2. Transfer operation of high unit loads judiciously

3. Flatten the load curve and maintain a high load factor

4. Avoid starting and stopping of high HP motors simultaneously



5. Stagger timings for working of machines and recess

6. Avoid idle running of machines

7. Make optimal use of storage facilities

8. Provide programmable timer controls for exhaust fans in cascade

9. Install capacitors with plastron control and low dielectric losses

10. Assess average and peak load power factors and redesign capacitors

11. Maintain peak load power factor around 0.95

12. Balance capacitor as per load

13. Inform power house before switching on heavy loads.

Distribution system:

1. Minimize LT distribution by increasing HT distribution system

2. Provide ring main system for HT & LT distribution system

3. Provide parallel paths and multiple runs of cable

4. Draw balanced circuits from secondary of distribution transformers

5. Check cable size and current carrying capacity

6. Redistribute loads to avoid circuitous feeding

7. Ensure equitable distribution of loads on available parallel paths

8. Install separate distribution switchboards for power and lighting circuits

9. Replace old paper cables with new PVC/XLP cables

10. Balance loads on all three phases within + 1%

11. Install capacitors near load points or at sub distribution board

Electric Drives

Motors:

1. Avoid under-loading

2. Choose motor size to match load

3. Use highest possible motor speed.

4. Motor loss increases from voltage imbalance.

5. Use a high efficiency motor instead of a standard induction motor

6. Replace rewound motors by standard motors if required

7. Switch off idle motors. In certain cases use automatic control

8. Use variable speed motor if process requires varying conditions

9. Use DC variable frequency drives instead of slip motors

10. Use soft starters with energy saver for high starting torque

11. For two-speed applications use high efficiency motors

12. Avoid loose or excessively tight ‘V’ belts.

13. Lubricate bearings regularly



14. Adopt misalignment of equipment, frozen bearing and belt drag.

Motor drive installations:

1. Connect appropriately rated capacitors across motor terminals

2. Choose capacitors of higher voltage rating than the supply voltage

3. For heavy duty Y-∆ installation, start motor preferably with contactor

4. Check voltage at points of use

5. Optimize operation with automatic controls

6. Use adjustable timers in batch and short run operations

7. Avoid idle running or under load run of conveyors

8. Avoid oversized equipment

9. Limit plugging and reversing of motors

10. Replace stalling torque drives with hydraulic cylinders/fluid couplings

Lighting system

1. Maximize use of natural lighting by lighter walls and surfaces

2. Use day lighting effectively

3. Avoid use of incandescent/tungsten filament lamps

4. Use electronic ballast instead of conventional chokes

5. Localized or task lighting consume less energy

6. Evaluate and revise lighting maintenance program

7. Clean luminaries, ceilings, walls etc., on a regular schedule.

8. Install local switching and dimmer controls for flexibility

9. Consider photocells and time clocks for turning exterior lights on and off

10. Install selective switching of luminaries’

Compressed air system

1. Locate and repair all leaks

2. Keep nozzles and valves in good condition and inspect regularly

3. Minimize ‘No-load’ operation

4. Consider change-over to smaller compressor if required

5. Ensure cold and dry air intake

6. Clean air inlet filters regularly

7. Install manometers across filter and monitor pressure drop

8. Ensure cleaning of fouled inter coolers

9. Use regenerative air dryers

10. Use FAD test to check operating capacity and leaks

11. Examine waste heat recovery and use

12. Minimize cooling tower fan consumption with control circuit



13. Monitor cooling water temperature and quality

14. Consider two or multistage compressors

15. Reduce compressor delivery pressure wherever possible

16. Provide extra air receivers at points of high periodic air demand

17. Retrofit modern speed regulation controllers in big compressors

18. Operate solenoid valves fixed in cycle punch press blow off nozzles

19. Optimize automatic electronic moisture drain trap timings

20. Periodically adjust tension in drive belts

21. Replace V-belts with modern flat belts

22. Lubricate all pneumatic equipment properly

23. Discourage misuse of compressed air for body cleaning

24. Operate pneumatic equipment at recommended pressure

25. Replace pneumatic instrumentation by electronic instrumentation

26. Check manual drains to prevent condensate build up

27. Check safety valves to prevent excessive pressure and wear

28. Check for air leakage in by-pass valves of reservoirs

29. Use delay timers to limit number of motor starts

30. Operate blow guns for clearing swarf or moisture at low pressure

31. Check lubricating oil consumption

32. Check pH of inter-cooler condensate for acidity

33. Check excessive vibration

Refrigeration

1. Reduce display lighting on refrigerated cases

2. Set thermostats to higher temperatures, if possible

3. Load freezers immediately after receipt of product

4. Control moisture sources to reduce defrost cycling

5. Minimize door opening and infiltration

6. Clean filters, heat exchangers and ducts regularly

7. Identify excessive demand and components with low efficiency

8. Check air inlets

9. Check and analyze summer heat production

10. Shut off air-conditioning in unoccupied areas

11. Eliminate unnecessary exhaust hoods and roof ventilators

12. Avoid artificial cooling where not needed

13. Minimize operating time in areas with varying occupancy

14. Eliminate artificial ventilation where air quality, noise, loads permit



15. Check possibility for intermittent use of AC system

16. Maintain required temperatures

17. Avoid infiltration of outside air and dust

18. Use sunshades optimally. Install glass or double paned glass

19. Use chilled water temperature at highest possible level

20. Check seals for oil leaks

21. Improve controls on refrigeration system

22. Install automatic shut off for fans on cooling towers

23. Install time switches for shutdown, start-up and part load operating

24. Change air paths to reduce airflow rates

25. Explore two-stage cooling, with cooling tower water and then chiller water.

ENERGY AUDIT OF INDUSTRIES

The manufacturing industry in India, accounts for over 50% of total commercial energy used

in the country. Across the world, industry consumes about 1/3 of all natural energy sources. Hence, it

is very important to concentrate on conserving energy in the industrial sector.

Normally electricity and HSD are the main energy sources to any industry. Electricity is used

for driving motors of air compressors, refrigeration compressors, pumps, fans, blowers, machinery,

welding sets and lighting. HSD is used for running DG sets, which are used in case of power failure

from the grid. Electricity may also be used for heating and drying ovens etc. and for other

applications. Some industries use coal, bagasse, rice husk etc. mainly for steam generation.

The major energy consuming equipment/systems in a typical industry are listed below:

Electrical systems

Electric drives

Steams system

Furnaces

Compressed Air System

Air Conditioning & Refrigeration

Pumping systems

Cooling Towers

Fans and Blowers

Lighting System

Diesel Generating Sets

Brief scope of energy conservation in the above equipment/system is given below

Electrical Systems



The scope in Electrical System comprises of transformer loading practices, Power Factor

Management, analysis/optimizing Voltage levels, Distribution losses and Harmonic levels. A

specific observation on daily load curve for possibility of further suppression of demand especially

during peak load hours will be looked into.

Electric Drives

Following recommendations could be made based on actual measurements and analysis

Proper sizing of motor

Use of energy efficient motor by replacing oversized and less efficient motors

Retrofitting inverters or soft-starters

Re-shuffing of motors as per loading

Possibility of operating motors in star mode wherever motors are under-loaded

Reactive power compensation for motors

Steam System

An in-depth study of steam system covering steam generation, distribution and utilization would

cover the following:

Efficiency evaluation of boiler by indirect heat loss method

Optimum steam generating pressure

Quantification of steam leakages

Steam trap survey

Insulation aspects including insulation surveys

Optimization of steam utilization

End use equipment (generally, heat transfer equipment, viz. driers, etc.)

Alternate (cheaper) fuels for combustion.


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