HOW TO USE THIS GUIDE

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2 Contents 1. BACKGROUND 2 2. HOW TO USE THIS GUIDE 3 3. INTRODUCTION 5 4. PLANNING THE ENERGY AUDIT DATA COLLECTION MEASURING ENERGY USE IDENTIFYING OPPORTUNITIES COST BENEFIT ANALYSIS REPORTING POST-AUDIT ACTIVITIES MONITORING & MEASUREMENT EQUIPMENT WATER AND WASTEWATER 27 Appendix A INDUSTRIAL LIGHTING 28 Appendix B COMPRESSED AIR 36 Appendix C BOILERS AND FIRED HEATERS 46 Appendix D REFRIGERATION & COOLING 57 Appendix E ELECTRIC MOTORS & DRIVES 66 Disclaimer LIMITATION: This guide has been prepared on behalf of and for the exclusive use of Sinclair Knight Merz (Europe) Ltd s Client, and is subject to and issued in connection with the provisions of the agreement between Sinclair Knight Merz (Europe) Ltd and its Client. Sinclair Knight Merz (Europe) Ltd accepts no liability or responsibility whatsoever for or in respect of any use of or reliance upon this guide by any third party. Output No: PAGE i Document JC30631-N-CG-GL-0004

3 1 BACKGROUND 1. BACKGROUND This guidebook has been developed by SKM Enviros and BRE on behalf of the Ministry of Industry, Commerce, and Consumer Protection, in conjunction with UNDP, the Ministry of Energy & Public Utilities, and the Energy Efficiency Management Office of the Republic of Mauritius. Funding for the implementation of this project has been provided by GEF and AOSIS/SIDSDOCK, through UNDP. This guidebook is provided as part of a wider programme to facilitate industry in Mauritius to implement Energy Management and conservation in Mauritius. The programme provides the following elements: Guide book on energy auditing in industrial applications Guide book on energy management in industrial applications Software calculator tool to estimate and record identified energy saving opportunities Theoretical training in energy management Theoretical training in energy auditing in industrial applications Practical training in conducting energy audits in industrial applications This guide book is intended as a self-help guide for use by personnel working in industrial facilities in Mauritius in the assessment of energy saving opportunities. This guide book is intended to be used in conjunct ion with the software based calculator tool to estimate and record energy saving opportunities. Output No: PAGE 2 Document JC30631-N-CG-GL-0004

4 2 HOW TO USE THIS GUIDE 2. HOW TO USE THIS GUIDE This guidebook provides a basic introduction to the practical aspects of energy audits and surveys in industry. It is not an exhaustive manual but identifies the key steps required to plan the audit process, gather relevant performance data, identify opportunities and report the findings. Energy auditing is a core component of any energy management system; unless energy use can be measured it is difficult to control and, without baseline performance metrics, a site s performance improvement cannot be measured over time. Whilst auditing a site that has a limited number of energy meters is a difficult proposition, there are ways of gathering sufficient information to allow a practical engineer to make an educated assessment of the breakdown of energy usage across a complex manufacturing plant and identify suitable energy saving opportunities. This guide is organised in the following way: Section 3 is an introduction to the objectives, information requirements and preparative steps required to begin the audit. Section 4 outlines the step-by-step process that makes up an energy audit and how to plan the approach depending on whether the audit is aimed at a site-wide or a single process department. Section 5 covers the essential data requirements and how to organise the data for effective performance analysis. Section 6 covers energy measurement, analysis and the importance of baseline reporting. Section 7 includes some suggestions for identifying opportunities to reduce energy use and managing the development of opportunities from initial concept to implementation. This section also links into the Technical Appendices, which outline opportunities across common technologies including simple checklists to guide the auditor through the processes. Section 8 is a summary of cost-benefit analysis, helping to develop the justification for investment in energy efficiency. Section 9 covers the contents of an audit report Section 10 highlights the follow-up activities that, when carried out on a regular basis, form the core of any energy management system that is consistent with the ISO standard for energy management. Section 11 introduces some of the useful hand-held monitoring tools that can be used to verify process conditions and check parameters such as power consumption and combustion efficiency. Section 12 is a reminder that water is also an important utility and opportunities to reduce water use can also deliver energy savings through reduced pumping and treatment needs and eliminating energy loss from hot effluents. Output No: PAGE 3 Document JC30631-N-CG-GL-0004

5 2 HOW TO USE THIS GUIDE The five Appendices cover specific issues around key universal energy technologies: Lighting Compressed air Steam systems and fired heaters Refrigeration and air conditioning Electric motor driven systems. Included in the appendices are checklists that may be referenced during the course of an energy audit that cover key energy using aspects of equipment. To complement this guide is a software tool comprising two parts: a database for recording energy saving opportunities and a series of simple calculators for estimating possible savings potential. Both parts require the user to enter data. The assessment tool home screen provides guidance on how to use the database and calculators. It informs where data input is required and where calculation outputs can be found. References to the software tool are made in this document by the calculator icon (left). The icon indicates that the information presented is supported by a calculator in the tool. References to the information in this guide and use of the software tool will assist the reader in identifying and evaluating potential energy saving opportunities. Output No: PAGE 4 Document JC30631-N-CG-GL-0004

6 3 INTRODUCTION 3. INTRODUCTION Carrying out an energy review is the first step for energy management. The energy audit is the starting point from which an energy review can be carried out and thus a rational energy management programme may be developed. It helps to quantify the energy usage at a site and highlights areas for potential savings and gives the data from which performance indicators can be derived. An energy audit is essentially a study to determine the amount and cost of energy consumed and to identify opportunities for potential savings. This is achieved by carrying out a technical investigation of the control and flow of energy in the plant or a process, or even a specific piece of equipment Objectives An energy audit helps to identify where and how energy savings can be achieved. Energy audits can be undertaken for the whole site, for a particular process or item of equipment. Whatever the subject of the audit, the objectives of the survey remain the same. The objectives of the energy audit are to: 1) Quantify energy consumption for audit scope (site, area or item of equipment) 2) Identify practical energy saving projects. 3) Quantify savings in energy and monetary terms Determine current position The first objective for a site energy audit is to quantify the amount of energy consumed on site. This will determine the current baseline position and will allow for the current situation to be assessed. When starting an Energy Management initiative it is important to determine the current position. This is necessary as it will facilitate the setting of goals and priorities for future development. There are various elements of the current situation that need to be defined. These can be divided into two main categories: Quantity elements: How much energy is being used? Quality elements: Where and how is energy being used? Quantity elements The quantification of current energy consumption and cost is a good starting point. In addition to indicating the magnitude of energy consumption it also helps to inform where to concentrate efforts to achieve the best results. Output No: PAGE 5 Document JC30631-N-CG-GL-0004

7 3 INTRODUCTION Monthly consumption figures over a 12 month period provide a useful method of producing a picture of energy usage. It is also important to record the type and energy intensity (calorific values) of any non-standard fuels although it can sometimes be difficult to obtain this information. Fuel costs are obviously important and any month by month variations should be noted. Cost information should include the unit cost of fuel and supply tariff (if applicable). The source of fuels and any variations in calorific value or quality should also be recorded. The following issues need to be investigated in order to establish the current position: Energy sources: Identify all the fuel types and energy sources used on site. These can include Electricity, Liquid Petroleum Gas (LPG), Heavy fuel oil, etc. A list of common fuels is included in the Audit Tool, including typical energy content and carbon equivalents. Amount of energy: Quantify the amount of energy used of each fuel type. All fuel types will need to be quantified in the same units (i.e. kwh, MJ, etc.) so that their energy consumption can be compared. Consolidating all the information will give the total energy consumption of the site. However, it is useful to be in a position to determine the energy usage for each area of the plant. In cases where the plant is zoned or different areas and/or particular equipment can be measured, the energy consumption for each area should be determined. This will help to target particular areas or processes or big energy users. For example, quantifying the electricity consumption for compressed air or for a specific production line will give an idea of where energy is actually being used. Cost of energy: The annual energy consumption cost of the site is needed so that the size of the problem is clearer. Energy cost can be compared against other baseline costs of the site. Moreover, the cost for each fuel will be different. Therefore, it is important to establish energy unit costs for each fuel. Again, it helps if all fuels have the same units so that they can be compared with each other. The Audit Tool incorporates typical calorific values of the fuels and normalises energy costs per unit of energy. Energy breakdown: Having established the energy used from each fuel type, and their respective costs, it will be possible to create a fuel breakdown. This can be done both in energy and monetary terms. CO 2 breakdown is also helpful when looking at the environmental impact of the plant. Furthermore, an energy breakdown by area or even equipment is a powerful tool which helps to identify big energy users and allow the audit to focus on areas where the greatest saving opportunities can be found Quality elements Having established the cost and quantity of each energy source being consumed, the next step is to identify where and how energy is actually being consumed. This in effect is the assessment of the flow of energy through the site. The objectives at this stage are to identify for each fuel the most important users in cost and consumption terms and to break down the usage as much as possible. Once this has been carried out, it will be possible to identify areas and specific items of plant to target for efficiency Output No: PAGE 6 Document JC30631-N-CG-GL-0004

8 3 INTRODUCTION improvement measures. Once areas that require improvement or areas where energy is wasted have been spotted, the next step is to find out how and why. In order to assess the way energy is being used a plant walkabout will be necessary. Plant walkabouts are discussed in more detail in the following chapters. However, at this point it needs to be mentioned that during the walkabout it is important that anything that could be done differently is questioned. This will help to identify process inefficiencies and areas of energy wastages. The objective here is to reduce energy consumption and improve energy efficiency. These are two different issues and should not be confused. There are two main questions that always need to be answered in terms of energy reduction and energy efficiency: Energy reduction - Is energy actually needed? This relates to the areas where energy is being wasted. Old practices are not always the best practices. An investigation into such areas can help to identify significant energy saving opportunities with no or very low cost. Energy efficiency - Can it be done more efficiently? This relates to how energy is controlled and/or is converted from one form to another. For instance the efficiency of air compressors can be improved simply by drawing in air with lower temperature, so that the conversion efficiency of power to compressed air is improved. Energy Reduction Energy Efficiency Areas of inappropriate use or waste Are we heating and cooling at the same time? Are lights sleft on in an empty room? Are ovens left on while there is no production? Poor control or conversion efficiency Are we using the appropriate efficient equipment? Are we controlling machines properly? Is there a better way 3.2. Required information As discussed above the types of fuel used need to be known. Electricity, Liquid Petroleum Gas (LPG), Heavy fuel etc. should be identified and quantified. It might be more appropriate to treat compressed air and steam as separate utilities starting from the output of compressor / boiler. This will allow for a more focused analysis on particular equipment and processes. What needs to be identified is: The quantity of each fuel: The energy consumption data can be retrieved from the utility suppliers or metering on the site. The unit cost for each fuel: The utility suppliers will also be able to provide the unit costs. Furthermore, cost breakdown for each fuel type should also be known. For example, the day and night, or peak tariff cost rates for electricity is important for comparison with operation and energy use patterns. Output No: PAGE 7 Document JC30631-N-CG-GL-0004

9 3 INTRODUCTION Where and how each fuel type is used: Where sub-metering is in place data can be available for specific areas, or equipment. For example useful information can be found in the boiler house or the compressor house log book. Gathering information about energy consumption is an important process and it is important that all data is recorded properly. The following table is an example of how to record the required information. Year 2012 Site / area Energy source Units Quantity purchased in original units Quantity converted in kwh Cost Unit Cost $/kwh CO 2 (tonne) Electricity kwh 2,750,000 2,750,000 $330, ,460 Natural Gas m 3 840,000 9,240,000 $323, ,760 Oil litres 42, ,200 $25, Other fuel Total ,435, , ,616 The data from the above table can be used to create a breakdown of all the energy sources on site. A pie chart is very useful to visualise the various breakdowns. An example is shown below: Energy Breakdown Cost Breakdown CO 2 Breakdown Oil 4% Electricity 22% Oil 4% Electricity 48% Oil 3% Electricity 44% Natural Gas 74% Natural Gas 48% Natural Gas 53% Output No: PAGE 8 Document JC30631-N-CG-GL-0004

10 3 INTRODUCTION From the above figures it can be seen that whilst electricity supplies only 22% of the energy requirement, it accounts for 48% of the cost. Therefore, small energy savings in electricity can bring more significant cost savings. After the baseline is determined it is useful to look at the most significant energy users on site. Creating a list with all the major users will help in identifying areas where greatest focus should be given for identifying savings opportunities. The list below contains examples of typical users on industrial sites. When sub-metering is available it helps to measure the actual consumption by each user and they may be sorted accordingly. Where sub metering is not available and a user is known to be significant portable sub metering equipment may be used to take temporary measurements to inform an understanding of the actual energy use. This type of information is needed to establish the current baseline and to identify and estimate energy saving opportunities. However, additional information will be needed to assess the practical and economic feasibility of any energy saving projects identified. The required information for assessing the feasibility of the projects can include: The cost of energy saving projects: Having accurate cost estimates for any required improvements / modifications needed to deliver savings will help to estimate the payback period of the project. This will allow the proposer to provide a business case and helps to make an informed decision on whether to invest or not. Operation pattern of the plant: This is needed when considering changes that will have an effect on or depend on operation patterns. For example, a process heat recovery project will depend on the time when heat is needed. Electricity users Ovens Furnaces Presses Air compressors Chillers Hydraulic pumps Dust extraction system Lighting Air conditioning Motors on conveyor belts Fork lift trucks Hot water boilers Induction furnaces Space heating Liquid Fuel users Steam boilers Thermal fluid heaters Hot water boilers Ovens Furnaces Space heating Presses Vehicles It is also important to establish the priority areas. The auditor needs to know whether to focus more on no/low cost projects or on bigger energy saving projects: No/low cost measures can bring fast results and boost confidence but savings may be limited whereas, Bigger projects on major energy users can give significant savings but may need more time and capital investment. Output No: PAGE 9 Document JC30631-N-CG-GL-0004

11 4 PLANNING THE ENERGY AUDIT 4. PLANNING THE ENERGY AUDIT 4.1. Setting the scope The audit may cover an entire site, the services operations or a single production unit. To ensure that the appropriate information is collected during the audit the scope of the study should be clearly defined. However, the energy auditor should also be aware of and note other energy issues that might be observed during the course of an audit (for example, noting a compressed air leak on an adjacent piece of equipment or questioning significant water usage). For a basic consumption or carbon footprint audit it will be sufficient to collect records of energy invoices for at least the past 12 months or past calendar year. This type of audit will be appropriate for high level reporting of energy consumption, cost and carbon emissions, typically used for annual reporting to shareholders or government or as a pre-audit for a more comprehensive audit of the site or process. In this case, no on-site visit is required; the audit can be completed in an office environment with access to top level energy reports and utility invoices. The next level of audit is likely to be an assessment of the breakdown of energy use across the various processes on site. This requires a more careful approach as it will involve access to boilers, compressor houses and sub-stations to view any sub-metering and switchgear. It will also require access to utility distribution drawings and a visual inspection of large motors and heaters (or access to a motor inventory) to draw up a list of the main energy consumers. For this type of audit an escorted tour of the factory is required, so an appropriate safety briefing is required from site, including relevant Personal Protection Equipment (PPE) where necessary. A detailed site audit with the primary objective of identifying opportunities is likely to take one or more days depending on the size of the factory. In this case the auditor may need to access the site independently, to view all major process plant and site services equipment. For an energy management assessment the auditor will need to meet senior managers, production supervisors and plant operators to enable him to make an assessment of the organisation s capability to implement energy management change. So, check before arrival that such people will be available either collectively on a one-to-one basis to help you form an opinion of the company s energy management maturity. Finally, always prepare in advance of a visit check the company s website for any technical background, understand the production processes and inform your host contact of your visit plan so he can ensure you have the appropriate access to people, reporting systems and technical information. Detailed audits need to be undertaken by the appropriate persons or team. They need to be experienced and familiar with the site s operations. The skills required cover technical, safety, accountancy and management aspects. The main skills needed are summarised below: Output No: PAGE 10 Document JC30631-N-CG-GL-0004

12 4 PLANNING THE ENERGY AUDIT Data handling skills: Data is necessary to analyse performance and assess efficiency. In view of the large quantities of data analysis involved, familiarity with and access to computers is useful. Communication skills: Auditors should have good people and communication skills, sufficient strength of character to question the obvious and initiative to find solutions to problems. Technical understanding: An in depth knowledge of specific equipment in use at the site is desirable but not essential, as design information can be obtained at a later date; a feel for product flows and site services is more important. Open minded: An open mind is essential. Usually people continue doing things even when they know that there is a better way. The fact that things have always been done like that doesn't mean it is the right way. A tour around the plant should follow the process from the raw materials to final product. Each stage of the process needs to be understood. Particular attention needs to be given to: 1) Energy flows into and out of processes. 2) Raw material and product flows. 3) Wastage and effluent flows. The pattern of operation is also important. It needs to be defined whether the process is in operation for 8 hours per day or 24 hours per day. Also the type of the process (batch or continuous) needs to be identified. For instance, in the case of a batch process the start and finish times as well as the factors that dictate them need to be identified. All the important process parameters need to be highlighted and investigated. The answers to these issues and others will only be gained from talking to the key people at the site who are: 1) Process operators. 2) Process supervisors. 3) Production managers. Offices STORES It is very important that these people are involved in the audit. It is helpful to identify how they see their job and what affect this can have on energy consumption. The auditor needs to be open-minded and to ask questions and even challenge them. Operators will continue to stick to poor, old practices if unchallenged, as it is easier than changing. Boiler house Production 2 Production 1 A forward thinking factory will have an energy team, or even energy teams for each production area. Team members are useful; sources of information and process knowledge and will also be custodians of any opportunities, so be sure to make time to meet the energy team, either as a group or individually. Production 3 Output No: PAGE 11 Document JC30631-N-CG-GL-0004

13 4 PLANNING THE ENERGY AUDIT It is recommended that the plant is divided into appropriate zones. This will help when planning the walkabout and it also helps to focus on appropriate areas. As best practice the site layout with the associated zones should be in hand when doing the plant walkabout. An example of a zoned plant is shown on the previous page. Then, a list with the services and technology used on site can be created on which the auditor can use to track the audit process for every zone. An example of such a matrix is shown below: Technology topic Zones Offices Stores Boiler house Production 1 Production 2 Production 3 Lighting Ventilation Space heating Air conditioning Hot water Steam Hot oil Compressed air Chillers Dust extraction Building fabric Motors and drives Fans and pumps Conveyor belts Process heat Distribution Output No: PAGE 12 Document JC30631-N-CG-GL-0004

14 4 PLANNING THE ENERGY AUDIT 4.2. Health and safety considerations The health and safety of the auditor, host company employees and other contractors must always be at the forefront of planning an energy audit. The auditor may wish to use intrusive portable monitoring equipment such as gas analysers or electrical clamp on meters to gather data in which case the relevant permits to work need to be obtained; these are usually accompanied by descriptions of how the work will be carried out and the site will assess these to ensure the proposed activities are safe. Always check with your site host and health & safety manager to ensure that the equipment is fit for purpose and its use is acceptable on site. Always ensure that you have appropriate Personal Protection Equipment (PPE), either your own personal equipment or request this from site. Most companies will have a recognised safety induction for visitors and contractors; always ask to see either an induction video, slide deck or safety procedures sheet. Always be aware of site safety issues, do not be afraid to point out an unsafe act or near miss and stop work and be prepared leave site if you are uncomfortable with the working environment Timescales The time required to deliver an energy audit will depend heavily on the scope requested by the client. A short audit of annual energy use for carbon or sustainability reporting may only require a day onsite and two days to write up, while a detailed survey of a large production facility aimed at identifying opportunities could take weeks or even months. Some rules of thumb to assist in planning are audit are as follows: Allow 3-4 weeks for the site to assemble the requested energy and process information Allow 1 week before the kick-off meeting to carry out preliminary analysis of plant data (KPIs, high level regressions etc.) Time on site will depend on the scale of the project. Allow 4-5 man days for every 2 million (R50 million) of energy spend (your knowledge of the site and process will help to guide you to set site days). Allow 2 analysis and reporting days for every site day. This can be reduced if there is a relatively small number of process operations but at least as many man-days as you spend on site. Allow 2 weeks for the site to review and comment on the draft report before a close-out meeting. Follow up the close-out meeting within one week with the final report. Output No: PAGE 13 Document JC30631-N-CG-GL-0004

15 5 DATA COLLECTION 5. DATA COLLECTION 5.1. Assess the current situation Audit information should be prepared in such a form as to allow comparison with historical data or available industry figures. Comparison between sites may also reveal opportunities for saving. It has already been mentioned that determining the current position is the starting point of the energy audit. The use of the most recent 12 months historical data will help to calculate the annual energy consumption. This will represent the baseline. Establishing a baseline is important as future savings and energy performance will be measured against it. It is useful to gather weekly or monthly base data on consumption and expenditure over the last year(s). The information that needs to be gathered will include not only energy consumption but also data for the factors affecting energy usage. Even though the source of this various information will be different (energy invoices, log books, accounts, etc.), it is recommended that all the information is kept in a central place where access will be easy for someone wishing to review them. A simple table with the data required is shown below: January February Etc... Total Month Electricity (kwh) Natural Gas (kwh) Degree Days* ( C) Production (kg) Degree days for heating or cooling may be an important driver for fuel consumption or chiller demand The above table can also include for example different product groups, utility costs, energy consumption by area, and information on throughput including overall production and production by area or process. Data collected in such a form allows performance indicators to be established in terms of specific energy ratios relating energy usage to production, usually expressed as the energy requirement per unit of production or Specific Energy Consumption (SEC). The units used will vary dependent on the fuels used and the type of product. However, a consistent unit is recommended. The pattern of energy consumption is analysed and correlated with raw materials input, product output or hours run for production related energy usage; and factors such as average ambient temperature for space heating. Output No: PAGE 14 Document JC30631-N-CG-GL-0004

16 5 DATA COLLECTION Data collected in such a format is also easy to analyse using regression analysis to establish any relationships between energy consumption and production activity or climate factors (e.g. degree days). Such analysis can form the basis for setting energy targets for those processes where we can see a strong relationship between energy and production activity.to develop a good idea of where the energy is being consumed a good understanding of the production processes involved is essential. When an auditor or the Energy Team from another site undertakes the on-site audit, then a plant walkabout is necessary to develop a feel for the site and familiarise with the processes. Typically, gaining an understanding of the production processes involves discussions with production management, a tour of the plant and the drawing up of a process flow sheet (block diagram). For each element of the flow sheet energy and raw material inputs, products, effluents and waste flows should be identified. Based on information available and visual checks, the relative size of energy flows and wastage should be estimated and the major energy users (both services and processes) should be listed. Sub-metering, where available, is useful in calculating the consumption of end users. A small saving on a large consumer will often be more significant as well as more achievable than a large saving on a small user. This does not mean that small users should be ignored but initial efforts should concentrate on those areas most likely to produce substantial savings Review historical energy consumption information Historical data, perhaps extending back over two or three years, can be used to understand a site s progress in developing an energy efficiency culture. Although SEC values may often be influenced by production volumes and new production processes it is useful to see how performance has changed. If detailed data are readily available they can be used to establish historical baselines and regression models. Then, the impact of any changes to the site operation can be assessed and quantified through CUSUM analysis. Comparing performance indicators such as those mentioned above with internal and /or manufacturer standards will then enable a prioritisation of the results into categories according to the outcome: Good results Action is not urgent. When the results show that the energy performance is good then it can be said that no action is urgently needed. However, the energy audit will need to be carried again in the future to ensure that good performance is maintained. Average Action required. Average results will mean that there are deficiencies and issues that need to be resolved. Poor Urgent action is need. When the results indicate poor energy performance, urgent action will be needed. However, it should be noted that even when the results for the site in general are good, specific areas or processes might not be in the same position. For example, the overall energy performance of a site could be good, but the compressed air system is inefficient with many compressed air leaks, poor control of the compressors, etc. Therefore, the analysis should look not only on the overall plant performance but focus on the various processes and systems within the plant. Output No: PAGE 15 Document JC30631-N-CG-GL-0004

17 6 MEASURING ENERGY USE 6. MEASURING ENERGY USE 6.1. What to look for The initial design of a system may not have been optimised. Often, an easy option or one with a low capital requirement will have been chosen, not the cheapest running cost option. The status quo should not be accepted without question. Whether the energy flows are reasonable or not needs to be established. An understanding of the processes involved and knowledge of appropriate available technologies will be needed to identify better options. When undertaking an energy survey on specific equipment (i.e. air compressors, boilers, steam systems, etc.) the relevant appendices at the end of this guide can be used. These provide useful information on where focus should be drawn. However, there are things that can be easily identified during the audit and the auditor should constantly be looking out for areas of energy waste. A list of things that can be easily picked up during a walkabout is given below: Look Listen Feel Conveyor belts running unnecessarily Machine noise when no production Compressed air leaks Lights left on when not needed Dust extraction system on when not needed Room temperature too low / high Oven doors left open wasting heat Compressed air and hot water leaks Air draughts through open doors Doors left open when heating is on Motors left running when not needed Hot un-insulated pipe work 6.2. Areas to focus When looking at energy usage, the energy onion provides a useful analogy to an energy system. The process or end user is at the centre of the onion, which determines the production-driven energy requirements of the site. Once this has been confirmed, the next layer of the onion is the energy distribution system - network of wires, pipes and ducts delivering power, steam compressed air and other utilities to the process. Once the distribution system has been reviewed, the methods of controlling the supply of energy through the networks to the process can be addressed. This could include pressure or flow controls in steam systems, voltage control in power systems or temperature control of chilled water supplies. Output No: PAGE 16 Document JC30631-N-CG-GL-0004

18 6 MEASURING ENERGY USE Having assessed the control of the energy supplies, the next layer of the onion represents the energy conversion plants. This is where primary energy supplied to site in the form of fuel and power is converted into useful utilities steam, compressed air, cooling etc. that are used by the production process. Finally, once you are happy that the energy conversion processes are appropriate it is time to address the outermost layer of the onion and review the energy supply contracts. End User: how energy is used within a specific process / piece of equipment Distribution system: how energy is distributed (compressed air, steam, water, hot oil distribution systems) Controls: how energy is controlled (energy management systems) Generation (conversion): how energy is converted (air compressors, boilers, boilers, chillers) Energy Supply: How primary energy is supplied to the process Energy end use Starting at the centre of the onion, it is important to understand how much energy the production process should require from a theoretical and practical standpoint. This should define the base energy demands for the process and act as a guide for the sizing of distribution networks. Where the end usage is inappropriate such as the use of compressed air for cleaning it may be possible to remove the load altogether. Where this is not possible, it may be possible to reduce energy consumption by reducing leakage or improving insulation. Reduced end usage demand will also reduce distribution losses as less energy will need to be distributed to meet the reduced demand. It may also be possible to rationalise the distribution system in the light of reduced end use. Investigations into reduced leakage, improved insulation, reduced supply pressure etc. may also increase distribution efficiency. Before looking at the conversion efficiency, good reduction opportunities should already have been identified. In reality it is often more difficult as end usage is the most difficult aspect to change. In looking at a process or large consumer the aim is to answer a number of questions. An example of a pump is discussed below: Question Why is energy required, and what is the process/plant item doing? Is the use necessary, and do we need to pump the fluid? Can the heat demand of the process be reduced? Do we need to pump all the fluid all the time? Can we better control the pump to meet our needs and reduce energy consumption? Rationale Familiarisation with the process. Load reduction opportunities. Investigate heat recovery opportunities Improve control and match generation to demand. Output No: PAGE 17 Document JC30631-N-CG-GL-0004

19 6 MEASURING ENERGY USE Question Is the pump motor larger than it needs to be? Is the pump correctly sized for the task? Alternative ways to meet the need? Do we need to pump the fluid at all? Could we use a gravity tank, is there some other method of accomplishing the task? Rationale Oversized equipment run inefficiently and waste energy. Old practices are not always the best ways to do a job. The situation may have changed considerably since the original design and the pump may not be required at all or a much downsized version may be sufficient. In any situation the focus should be first drawn on the most significant energy users. With the energy breakdown undertaken combined with the list of users mentioned in the third chapter, the major users for each energy source should be easy to classify. This will help in identifying significant saving opportunities and maximizing energy as well as cost savings Energy distribution Some rationalisation of distribution systems may be possible. There are several issues that need to be investigated when assessing distribution systems. First of all an assessment needs to be made to determine whether it is economic to decentralise certain loads. Identify any redundant pipe work and make sure it can be removed. Long pipe runs should also be an area to focus and make sure that pipe work is appropriately sized. For the purposes of this module a steam distribution system is used as an example. Below are a number of the issues to be addressed. Comparison of useful / parasitic loads: The actual product energy demand needs to be determined. Then the proportion of the total demand that is made up of parasitic loads such as pipeline pressure drops or pumping demands should be estimated. Pipe work: The correct sizing of pipe work is important. Retrofitting over time can exceed the capacity of base systems and increase pressure drop losses. Conversely, an older site where production plants have been decommissioned leaving an over-sized steam main may suffer from higher than expected standing losses. Insulation is also important, as proper lagging can help to reduce distribution losses significantly. There are several international standards for insulation; one useful reference guide is BS5422 (2009). Pumps and fans: For centrifugal pumps and fans the electrical power requirement varies as a cube law proportional to pump speed. The application of variable speed control can produce substantial savings in suitable applications. Steam Pressure: The higher the steam pressure the greater the losses in heat and leakage terms from the system. Flash losses in condensate and pressure losses in pipe work will also be greater. Output No: PAGE 18 Document JC30631-N-CG-GL-0004

20 6 MEASURING ENERGY USE Condensate Return: All recoverable condensate should be returned to the boiler feed water tank. Check to see how whether condensate is recoverable and if it is metered. If condensate return is metered, make sure that the rate is as expected. Similar issues should be investigated for other distribution systems, such as compressed air circuit, hot water, hot oil, etc Energy controls Once the process energy demand has been established and distribution systems assessed, attention can turn to the control of systems to deliver the required energy. No / low cost savings can frequently be realised by just improving the way the process is controlled. Controlling is very significant for compressed air, steam and hot oil systems. For example, sequence controls for two or more compressors needs to be optimised to ensure that the compressed air system delivers only when there is demand for compressed air. More sophisticated control systems are now available that makes multi compressor installations more efficient. When a system has an off-load control, there is a pre-set pressure range such that the compressor off loads at the higher value and loads at the lower. However, the main drawback is that an unloaded compressor will still consume between 20-40% of its full load power for on/off control and 70% for Modulation Control. For cases where several compressors of varying sizes are installed the selection of the most suitable compressor available for the prevailing duty is critical in terms of energy efficiency. The relative efficiencies of the machines should also be taken into account before setting up the control system Energy conversion To achieve savings in this area demands knowledge of the relevant technologies and what is current best practice. Design data on the plant concerned should be obtainable from documents on site or from the equipment manufacturers. Measured performance can then be compared to best practice, design or previous performance data. System Boiler Air Compressors Things to check Fuel / air ratio Exhaust gas temperature Feed water temperature Boiler blow down rate and total dissolved solids (TDS) levels Air intake temperature Moisture content of air intake Variance in the demand for compressed air Output No: PAGE 19 Document JC30631-N-CG-GL-0004

21 6 MEASURING ENERGY USE However, there are simple actions that can be taken to improve the conversion efficiency of a system. The list below summarises the items that need to be checked in an energy audit survey regarding conversion efficiency of boilers and air compressors: Further information regarding these can be found in the appendices at the end of this guide Energy supplies Energy supply and conversion often go hand-in-hand, as the availability of primary fuel will often determine the selection of boiler or power generation technologies. If there is a sufficient base load requirement for heat as steam or hot water and an acceptable supply of clean fossil fuel is available, a combined heat and power plant may make economic sense; in an appropriate location with access to a sustainable, managed forestry industry, there may be biomass available as an alternative fuel. Combined Heat and Power (CHP) or on-site generation may also be appropriate if there are grid capacity or reliability issues, and the energy audit should consider alternative fuel sources if appropriate Benchmarking and baseline definition A performance baseline is essential if changes are going to be made to process or service operations, so understanding the starting point is a critical stage in energy auditing. Often this will be a simple performance indicator expressed as kwh of energy consumption per unit of output (SEC). This is a useful measure when comparing performance with sister plants or competitors (if that information is published). Knowing where the plant stands in relation to an industry benchmark is helpful in deciding where investment or operational change is required. The disadvantage of using SEC as a benchmark is that the production volume inevitably dominates the calculation and it is all too easy to explain poor performance by saying that production was lower than usual. A better tool is to find a relationship between energy and production activity, so that variance needs to be explained in terms of poor or good operation or equipment malfunction. Managers can use such a variance analysis to catch and rectify poor performance at an early stage. Output No: PAGE 20 Document JC30631-N-CG-GL-0004

22 7 IDENTIFYING OPPORTUNITIES 7. IDENTIFYING OPPORTUNITIES Once the data collection phase of the audit is completed, the identification and costing of potential improvement measures and projects begins. This gives an opportunity to collate any ideas and to generate a prioritised list of potential measures. It is important at all stages to discuss ideas with the appropriate people to see whether similar measures have either been tried before and failed or considered before and rejected because of process or other limitations. Results should be communicated with the relevant stakeholders in order to evaluate the various measures. The objectives at this stage are to: 1) check what measures will work 2) check what measures are appropriate 3) study interaction with the measure and other projects 4) establish the cost of the measure 5) calculate benefits arising from the measure 6) compare rival measures and prioritise 7) reach conclusions 8) create action plan For each of the measures identified there are issues that need to be taken into consideration. There should be a check to ensure the measures are acceptable for: Environmental and Health and Safety reasons: Make sure the measure does not have a knock on effect and it does not breach existing or proposed regulations. Best solutions: Gains should be examined over the long term, not just the short term. Acceptable Solution: Take into account any other reasons that may prohibit the implementation of the measure. Approximate Costing: Budget figures for suppliers to give approximate area for costs It is also important to inform staff about measures that are being discussed and what the end goals are. This is vital, especially where measures include projects involving the installation of new equipment or controls. These measures will not deliver the expected savings without people being trained to use the new equipment. Last but not least feedback should be requested from the staff / operators. Ideally, the appropriate staff should be included in the survey. They are familiar with the various processes on site and they should be able to highlight energy wastages, process inefficiencies and to identify opportunities. Output No: PAGE 20 Document JC30631-N-CG-GL-0004

23 7 IDENTIFYING OPPORTUNITIES As best practice all identified opportunities should be recorded in a database. This will allow for future review of the status of each opportunity making sure that nothing is missed. A database of opportunities helps to inform an estimate of the expected savings. An example of the database as found in the software tool that accompanies this guide is shown below: The database should be reviewed frequently and be kept up to date. Output No: PAGE 21 Document JC30631-N-CG-GL-0004

24 8 COST BENEFIT ANALYSIS 8. COST BENEFIT ANALYSIS Opportunities generally fall into three categories: No-cost behaviour change, such as switching off lights, reducing thermostat set points or fixing leaks. These should need no financial justification and be implemented as a high priority. The decision to implement such projects should be within the remit of the plant manager, maintenance manager or energy manager. A certain level of awareness and procedures may need to be put in place to facilitate these. Low Cost projects that need little additional investigation and are likely to have a rapid return on investment but do require some expenditure. Ideally these should be funded from the revenue budget as they are likely to recoup the expenditure within the same financial year. The decision to implement such projects should rest with site management and should be integrated with maintenance schedules if possible. Capital investment projects that either require significant funding despite a short payback, or have a payback period in excess of one year. These usually require a financial justification and an investment requisition to be submitted for board approval. When considering capital investment projects, some far-sighted companies will ring-fence a proportion of capital for energy, environment or health and safety compliance projects. However, most companies will rank all investment opportunities in the same league table and implement those with the best rate of return. Energy projects will usually fall into a low risk category of investment they rarely involve adopting leading edge or untried technologies and the longer term value of savings is likely to rise in step with increased energy prices. In order to present an effective case to management to gain any form of commitment and investment, a transparent financial and technical appraisal must be put forward. Management will look more favourably on proposals that represent the best investment, that optimise benefits, that sufficiently address risk management issues and which include satisfactory performance analysis. Output No: PAGE 21 Document JC30631-N-CG-GL-0004

25 8 COST BENEFIT ANALYSIS 8 COST BENEFIT ANALYSIS In putting a case together the steps below should be followed: Identify potential savings. Identify measures. Establish the costs and savings. Calculate the key financial indicators: o Simple payback; o Gross/net returns and their rates; o Discounting and net present value (NPV); o Index of profitability (IOP). Optimise the return. Establish the size of the overall budget. Optimise capital expenditure. Prioritise the projects. The main issues that result in a failed case are poor base data, poor justification and the lack of a do-nothing scenario. Ensure the figures add up and can withstand scrutiny. Other factors that may make the case more favourable are including information on maintenance savings and estimating increased productivity. Whilst information describing simple payback, is easily presented it can lead to misleading results. In some organisations this may not be in their best interest as they will not lead to the best investment choice. This is because simple payback does not take into account savings over the lifetime of the project or the time value of money. Therefore, better simple metrics are net return (which is a measure of the benefit) and average net rate of return, which annualise this benefit over the lifetime of the project. Some organisations use discounting and net present value (NPV) for project evaluation. However, even sophisticated metrics have their limitations. For example the disadvantage of NPV is that it does not take into account the initial capital (CapEx) outlay. The most transparent metric is probably the index of profitability (IOP) which does take into account the CapEx outlay and should be at least 1 for a project to be considered. Larger projects can be financed in a number of ways such as energy services contracts and shared savings. Output No: PAGE 22 Document JC30631-N-CG-GL-0004