Role of Energy Audit in Energy Conservation

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications 94 Role of Energy Audi...
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MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

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Role of Energy Audit in Energy Conservation Sanjeev Kumar Department of Mechanical Engineering A.I.T., Ghaziabad, U.P., INDIA e-mail: [email protected]

Abhishek Saxena Department of Mechanical Engineering M.I.T., Moradabad, U.P., INDIA

P.V. Venkateshwara CST (ASTRA), I.I.Sc. Banglore, INDIA

ABSTRACT Energy is a crucial input for the development process of India. The need of the hour is therefore to meet the energy needs in the most efficient and the cost effective manner while ensuring the long-term sustainability. Energy audit is the first step to energy management of any organization or industry. Energy audit means any process which identifies and specifies the energy and cost savings in a particular system. Such an audit program will help to keep focus on variation which occur in the energy costs, availability and reliability of supply of energy, decide an appropriate energy mix, identify energy conservation technologies, retrofit for energy conservation equipment etc. A substantial saving is possible through energy audit. The paper highlights together the need for proper energy utilization and the importance of energy audit in energy conservation as well as the various concept of energy audit and its application for improving the heat recovery using more energy efficient processes, recycling of scrap and by-product, use of waste heat of boiler, building design, use of more natural light, operation of machine at peak efficiency etc. The paper also emphases the methodology of energy balance to achieve the said goal. Index Terms: Energy Conservation, Audit, Energy balance.

INTRODUCTION The term energy audit is commonly used to describe a broad spectrum of energy studies ranging from a quick walk-through of a facility to identify major problem areas to a comprehensive analysis of the implications of alternative energy efficiency measures sufficient to satisfy the financial criteria of sophisticated investors [1]. Numerous audit procedures have been developed for non-residential (tertiary) buildings. Audit is required to identify the most efficient and cost-effective Energy Conservation Opportunities or Measures. Energy conservation opportunities (or measures) can consist in more efficient use or of partial or global replacement of the existing installation. If, looking to the existing audit methodologies developed by ASHRAE (2000), it appears that the main issues of an audit process are [5-6]: 1. The analysis of building and utility data, including study of the installed equipment and analysis of energy bills. 2. The survey of the real operating conditions. 3. The understanding of the building behaviour and of the interactions with weather, occupancy and operating schedules. 4. The selection and the evaluation of energy conservation measures. 5. The estimation of energy saving potential. 6. The identification of customer concerns and needs.

Common types/levels of energy audits are distinguished below, although the actual tasks performed and level of effort may vary with the consultant providing services under these broad headings. The only way to ensure that a proposed audit will meet your specific needs is to spell out those requirements in a detailed scope of work. Taking the time to prepare a formal solicitation will also assure the building owner of receiving competitive and comparable proposals. Generally, four levels of analysis can be outlined (ASHRAE, 2000) [5-8]. 1. Level 0 – Benchmarking: This first analysis consists in a preliminary Whole Building Energy Use (WBEU) analysis based on the analysis of the historic utility use and costs and the comparison of the performances of the buildings to those of similar buildings. This benchmarking of the studied installation allows determining if further analysis is required. 2. Level I – Walk-through audit: Preliminary analysis made to assess building energy efficiency to identify not only simple and low-cost improvements but also a list of energy conservation measures (ECMs, or energy conservation opportunities, ECOs) to orient the future detailed audit. This inspection is based on visual verifications, study of installed equipment and operating data and detailed analysis of recorded energy consumption collected during the benchmarking phase.

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

3. Level II – Detailed/General energy audit: Based on the results of the pre-audit, this type of energy audit consists in energy use survey in order to provide a comprehensive analysis of the studied installation, a more detailed analysis of the facility, a breakdown of the energy use and a first quantitative evaluation of the ECOs/ECMs selected to correct the defects or improve the existing installation. This level of analysis can involve advanced on-site measurements and sophisticated computer based simulation tools to evaluate precisely the selected energy retrofits. 4. Level III – Investment-Grade audit- Detailed Analysis of Capital-Intensive Modifications focusing on potential costly ECOs requiring rigorous engineering study. In order to reduce energy consumptions for sustainable and energy-efficient manufacturing, continuous energy audit and process tracking of industrial machines are essential. Compared to other non-residential buildings that have been widely researched, industrial buildings are generally characterized by larger thermal loads, ventilation losses and pollution control requirements [3-5]. Begin this section with a summary list of Energy Conservation Measures that meet the financial criteria established by the facility owner or manager. For each measure, include the measure name, estimated cost, estimated savings, and simple payback in a summary chart. A one or two page description of each energy conservation measure and support calculations should follow this summary chart. Include the ECM description, energy use and savings calculations, and the simple payback, net present value or life cycle cost analysis. It’s also a good idea to discuss any assumptions that were made regarding operation or equipment efficiency. ECMs that were considered but fell out of current financial criteria should also be listed and identified as have been evaluated [5-6]. Poverty reduction and economic growth are the prime objectives of national policy. The standard of living of a country can be directly related to per capita energy consumption. India with over a billion people produces only 660 billion kWh of electricity and over 600 million Indians, a population equal to the combined population of USA and EU, have no access to electricity, and limited access to other clean, modern fuels such as LPG and kerosene [8-10].

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This constrained energy access is reflected, as shown in Figure 1, in the relatively low human development index of India. Enhancing energy supply is therefore a key component of the national development strategy. Over the past decade, gains in both poverty reduction and economic growth have been significant, and supported by energy growth which has been significantly lower than the economic growth [8]. Industrial sector consumes nearly half of the total commercial energy available in India. This is basically due to the fact that Indian industries are often energy inefficient and have least concern for energy conservation. Indian industry uses energy more intensively than is the norm in industrialized countries. While selected modern Indian units often display very high efficiency that approaches world best practice levels, the average intensity lags world best levels. Indian industry has undergone a transformation since 1991, the year the economy was opened to foreign investment and competition. Energy per unit of value added in the industrial sector has declined since then. However, there still remains considerable scope for continued improvement of energy efficiency in Indian industry, and for learning from both worldwide and Indian best practices.

ENERGY MANAGEMENT The need of the hour is therefore to meet the energy needs in the most efficient and cost effective manner while ensuring long term sustainability. Hence the effective energy management is no longer an option — it is a strategic business necessity. 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 [9-10]; ‘The judicious and effective use of energy to maximize profits (minimize cost) and enhance competitive positions’. Another comprehensive definition is; ‘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 and quality. • To minimize environmental effects.

A. Energy Conservation and Energy Efficiency

Fig. 1:  Energy consumption is a prime driver of the Human Development Index

While talking about the energy management, the two concepts, which are commonly discussed, are Energy Conservation and Energy Efficiency. Energy conservation and energy efficiency are separate, but related concepts. Energy conservation is achieved when growth of energy consumption is reduced, measured in physical terms. Energy conservation can, therefore, be the result of several processes and developments, such as productivity increase or technological progress. On the other hand Energy

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

Efficiency is achieved when energy intensity in a specific product, process or area of production or consumption is reduced without affecting output, consumption or comfort levels. Promotion of energy efficiency will contribute to energy conservation and is therefore an integral part of energy conservation promotional policies [11].

NEED OF ENERGY AUDIT FOR ENERGY MANAGEMENT Energy loss in any industrial process or plant is inevitable; it is a foregone conclusion. But its economic and environmental impacts are not to be taken lightly, thus explaining the growing need for industrial energy efficiency. Put simply, the level of energy efficiency a plant or process can achieve is inversely proportionate to the energy loss that occurs; the higher the loss, the lower the efficiency. Where and how do most of the losses occur, how much energy is actually lost and are they controllable or recoverable? The answers to these questions remain well concealed in a black box where once energy is input, we do not know what really happens to it inside and how much the loss are. It is only when we look into the black box and extract these details that we are able to ascertain the performance of the overall or process levels and respond more effectively to the weaknesses in energy management. Overall energy losses in a plant can result from losses due to designs that do not incorporate energy efficient specifications such as heat recovery option; operations that run on inefficient methods; and poor or non-energy efficiency-conscious maintenance programme. Reducing these losses will substantially increase the plant’s efficiency, but we need data to identify and quantify the losses and subsequently suggest suitable techno-economic solutions to minimize the losses. This data can be acquired through energy audits.

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economic and other organizational considerations within a specified time frame. 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”. An energy audit is an inspection, survey and analysis of energy flows in a building, process or system with the objective of understanding the energy dynamics of the system under study. Typically an energy audit is conducted to seek opportunities to reduce the amount of energy input into the system without negatively affecting the output(s).

A. The Role of an Energy Audit To institute the correct energy efficiency programs, you have to know first which areas in your establishment unnecessarily consume too much energy, e.g. which is the most cost-effective to improve. An energy audit identifies where energy is being consumed and assesses energy saving opportunities - so you get to save money where it counts the most. In the factory, doing an energy audit increases awareness of energy issues among plant personnel, making them more knowledgeable about proper practices that will make them more productive. An energy audit in effect gauges the energy efficiency of your plant against ‘best practices’. When used as a ‘baseline’ for tracking a yearly progress against the targets, an energy audit becomes the best first step towards saving money in the production plant. In any industry, the three top operating expenses are often found to be energy (both electrical and thermal), labour and materials. If, the one can relate to the manageability of the cost or potential cost savings in each of the above components, energy would invariably emerge as a top ranker, and thus energy management function constitutes a strategic area for cost reduction. Energy audit will help to understand more about the ways energy and fuel are used in any industry, and help in identifying the areas where waste can occur and where score for improvement exists. The energy audit would give a positive orientation to the energy cost reduction, preventive maintenance and quality control programmes which are vital for production and utility activities. Such an audit programme will help to keep focus on variations which occur in the energy costs, availability and reliability of supply of energy, decide on appropriate energy mix, identify energy conservation technologies, retrofit for energy conservation equipment etc.

Contents of an Audit Fig. 2:  Plant is like a Black Box.

ENERGY AUDIT In general, energy audit is the translation of conservation ideas into realities, by landing technically feasible solutions with

An energy audit seeks to the document things that are sometimes ignored in the plant, such as the energy being used on site per year, which processes use the energy, and the opportunities for the savings. In doing the same, it assesses the effectiveness of management structure for controlling energy use and implementing changes. The energy audit report establishes

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

the needs for the plant metering and monitoring, enabling the plant manager to institutionalize the practice and hence, to save the money for the years to come. The energy audit action plan lists the steps and sets the preliminary budget for the energy management program.

Analysis of energy use Identifying where energy is used is useful because it identifies which areas the audit should focus on and raises awareness of energy use and cost. The results of the analysis can be used in the review of management structures and procedures for controlling energy use. Analysis of energy use can be done by installing sub meters in different plant locations to pinpoint actual energy usage per area. This is a good source data for allocating energy use. The plant manager can also list all equipment used and the corresponding operating hours. With this information, he can create spreadsheet information and generate charts useful for analysis. Important Points to Consider When Collecting Site Load Data: Operating hours This can be gathered from plant personnel. It is important to ensure the accuracy of this data because much of the potential for energy savings lies on correct estimation of the equipment’s operating hours.

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heat. It makes sense to go on with the project, if, there is a net positive benefit from the project.

Action plan to set implementation priority After passing the cost benefit test, an action plan should be developed to ensure that the opportunities identified and implemented. The action plan should include all the major steps for implementing the opportunity as well as the people responsible. Furthermore, there should be a plan for monitoring the results. a. Type of Energy Audit The primary objective of energy audit is to determine ways to reduce energy consumption per unit of product output or to lower operating costs. Energy audit provides a “bench mark” (Reference point) for managing energy in the organization and also provides the basis for planning a more effective use of energy throughout the organization. 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. Thus energy audit can be classified into the following two types:

i. Preliminary audit

ii. Detailed audit

Duty cycle

Preliminary energy audit is a relatively quick exercise to:

Machines such as large electric motors have varying loads and hence, different power requirements.



• Establish energy consumption in the organization.



• Estimate the scope for saving.

Actual power consumed



• Identify the most likely and the easiest area for attention.

For electric power users, this is based on either 3-phase current/ voltage readings or power analyzer measurements (e.g., direct kW which incorporates power factor). For fuel users, tank readings of monthly consumption estimates and flow meters with a total that can be sources of the measurement.



• 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.

Identification of energy projects Opportunities for energy savings can range from the simplest, such as lighting retrofits, to the most complex such as the installation of a cogeneration plant. The important thing for consideration is to focus on major energy users and areas. Always apply the 80/20 rule, focus on the opportunities that provide 80% of the saving but require 20% of the input. After the preliminary identification of opportunities, spent more time on those which have shorter payback periods, is beneficial.

Cost Benefit Analysis The identified energy conservation opportunities should be analyzed in the terms of the cost of implementing the project versus the benefits that can be gained. If, assume, to install a heat plate exchanger for recovering of the waste heat, than there is a need to calculate the total cost of installation and compare that with the savings than one can derive from the recovering waste

A comprehensive audit provides a detailed energy project implementation plan for a facility, since it evaluates all major energy using systems. This type of audit offers the most accurate estimate of energy savings and cost. It considers the interactive effects of all projects, accounts for the energy use of all major equipment, and includes detailed energy cost savings calculations and project cost. In a comprehensive audit, one of the key elements is the energy balance. This is based on an inventory of energy using systems, assumptions of current operating conditions and calculations for energy use. This estimated use is then compared to utility bill charges. Detailed energy audit is carried out in three phases: Phase I – Pre Audit Phase Phase II – Audit Phase Phase III – Post Audit Phase

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

MATERIAL AND ENERGY BALANCE

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Table 1: On 1000 kVA Transformer

It is well known that if there is no accumulation inside the system, what goes into a process must come out. This is true for batch operation as well as for continuous operation over any chosen time interval. Hence, ‘Material and Energy’ balances have become a necessary tool of energy audit.

S. No.

Location

Lux Level

Recommended Lux Level [8]

1.

MCC Room

800-850

500-1000

2.

DG Room

300-400

200-500

Material balances are fundamental to control of processing, particularly in the control of yields of the products. Energy balances are used in the examination of the various stages of a process, over the whole process and even extending over the total production system from the raw material to the finished product.

3.

Ware House 1

250-300

100-200

4.

Production Block 1

200-250

200-500

5.

QC Lab

1000-1200

750-1500

6.

Production Block 2

200-300

200-500

Material and energy balances can be simple, at times they can be very complicated, but the basic approach is general. If the unit operation whatever its nature is seen as a whole it may be represented diagrammatically as a box, as shown in Figure 3.

7.

Ware House 2

150-200

100-200

8.

Ware House 3

200-250

100-200

9.

Utility

400-500

200-500

10.

Workshop

400-500

200-500



Table 2: On 1600 kVA Transformer S. No.

Fig. 3:  Mass and Energy Balance

Location

Lux Level

Recommended Lux Level

1.

Store Office

350-450

300-750

2.

Machine Area (CR 361)

950-1000

500-1000

3.

Machine Area (WE 365)

250-300

200-500

4.

Panel Room

400-450

300-750

5.

QC Lab

1200-1300

750-1500

6.

Production Office

400-500

300-750

7.

Finished goods area

200-250

100-200

8.

MCC Room

900-1000

500-1000

Lux level was found to be within limit at all the places.

The mass and energy going into the box must balance with the mass and energy coming out. The law of conservation of mass leads to a material balance.

Saving in lighting system by voltage optimization Measured load in kW

= 80 kW

Mass In = Mass Out + Mass Stored

Existing voltage level for 3 phase supply

= 420 V

Proposed voltage level for 3 phase supply

= 380 V

% reduction in voltage

= 10%

Saving in lighting load

= 10%

Saving in kW load at reduced voltage level

= 8 kW

Raw Material = Product + Waste + Stored Material ΣmR =Σ mP + ΣmW +Σ mS ...(i) The energy coming into a unit operation can be balanced with the energy coming out and the energy stored. Energy In = Energy Out + Energy Stored ΣER = Σ EP + ΣEW + Σ EL + Σ ES ...(ii)

Yearly power saving in kWh

= 8kW × 12 × 30 × 12 = 34,560 kWh/annum

CASE STUDY

The annual monetary savings @ 5/unit (Approx.)

This case study is a part of Energy Audit of Sakata Inx (India) Ltd., Bhiwari, which is a subsidiary of Sakata Inx Corporation, Japan and is now a global ink manufacturer and has a strategic alliance with Toyo Inks on a worldwide basis. Here, we are studying the level of illumination on different locations of the industry.



A. Observations All luminaries at various locations of the plant were observed and given in the Tables 1 & 2.

= 1,72, 800/-

Recommendations To achieve this saving we must install 75 × 2 Nos. [A servo voltage stabilizers having input voltage of 350 – 450 V range and output voltage of 380 V, will appropriate].

Investment

= 2, 50, 000



Simple Payback

= 1.5 years

MIT International Journal of Mechanical Engineering, Vol. 4, No. 2, August 2014, pp. 94-99 ISSN 2230- 7680 © MIT Publications

CONCLUSION An energy assessment (often referred to as an audit) is the key to identifying energy-saving opportunities. The traditional assessment is strictly a technical exercise, led by a mechanical or industrial engineer. It culminates in a summary document that lists recommended energy improvements, giving a brief description of each opportunity, along with its projected cost, savings, and financial payback. The assessment concludes with a presentation of the assessor’s findings. The client then decides when, and if, the organization will act on any of the recommendations. Industrial facilities face a variety of barriers to becoming energy efficient, including a general lack of awareness of energy waste and ways to reduce that waste. The challenge for an energy assessor is to make those benefits more obvious to the clients’ facility managers and their key staff. An even larger challenge is to ensure that facilities follow through on implementation. As the standard of living and human development index of a country are directly related to the per capita energy consumption, the enhancing energy supply has become a key component of the national development strategy. But because of limited resources of energy, the energy management has become important to utilize the energy most efficiently. So the effective energy management is no longer an option — it is a strategic business necessity. Energy Audit is the key to a systematic approach for decision-making in the area of energy management. It attempts to balance the total energy inputs with its use, and serves to identify all the energy streams in a facility. It quantifies energy usages according to its discrete functions. Hence energy audit is an effective tool in defining and pursuing comprehensive energy management programme.

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