Energy Savings – a Strategy in Utilities
This paper looks at energy savings potentials in utilities in industrial processes. We present a monitoring and targeting strategy proposal that will assist in realising sustainable energy savings in key energy user utilities in processes. We view the strategy from the basics of energy policy, examples of potential savings, through to the three key elements of an automatic Monitoring and Targeting solution (aM+T). We investigate the concept of Energy Accountable Centres (EAC's), and discuss this by way of examples of typical utility systems. We consider the monitoring solutions as a cycle combined with the savings strategies, and discuss the methodology of targeting, benchmarking, reporting and action to realise sustainable savings. The paper gives an overall conclusion based on industry experience both locally and internationally.
1. INTRODUCTION
Through the experience gained by Endress+Hauser in the field of energy savings over recent years, we have determined quite clearly that although there is a strong requirement in the country for energy savings by means of energy efficiency, the truth of the matter is that very few industrial users have clear views as to how they can make sustainable savings. We investigate the losses and saving potentials and offer some guidelines based on our global competence on how to approach an overall strategy to energy savings in utilities in the processes.
2. WHY MEASURE AND TARGET UTILITIES? Globally and nationally it is a reliable statistic that more than 10% of industrial electricity is used for the production of compressed air, and more than 40% of fossil fuel is used for the production of steam. This makes these areas of plant an obvious target for energy savings. According to the OIT/Department of energy, 75% of the life cycle costs of the average compressor are used on energy, with only 10% on maintenance and 15% on capital costs 1. Similarly, in boiler houses, the capital cost of the plant can easily amount to less than 1% of the overall life cost of a boiler plant, with the major cost going to fuel, water, electricity and other consumables 2. The potential for energy savings in compressed air plants alone range between 5 and 40% 3. Similar figures are available on steam applications 4. With these figures in mind, any first step in making energy savings has to be determining the current situation in the process prior to making any changes to the plant. With this data as a benchmark, the success or failure of any future savings strategy can be compared against this benchmark. |
Figure 1. Potential savings strategies |
3. POLICY AND STRATEGY
Actions that generally need to be taken in order to address energy use in an Energy Management Program (fig 2) may include one or more of the following:
An organization's energy policy should have agreed-upon objectives and demonstrate senior management's commitment. The policy's energy strategy should outline specific plans to achieve improved performance. |
Figure 2. Policy and strategy |
Training is essential to ensure that operations personnel understand key energy issues and what actions they need to perform in order to reduce costs. Activities to raise awareness can also be used to emphasize the need to reduce energy use and make the link between energy and the environment.
Energy audits are traditionally the foundation of an organization's energy conservation plan. Audits are usually carried out by experienced engineers and identify and quantify where energy is used and find measures for improvement. These measures may be low or no-cost changes or require capital investments. The auditor should ideally be a certified Measurement and Verification Professional.
Once opportunities are identified, they need to be developed into projects that can be justified and implemented. Developing the project includes accurate estimates of costs and benefits and assessments of practicality, safety and environmental issues.
It is critical that the plan is well structured and driven by an accountable individual, as ad-hoc approaches seldom if ever show long term or measurable results.
It is important to note that independently, savings can be made in these areas, but with a comprehensive programme and strategy to address all utilities, including water, fuel, steam and compressed air, these areas have the potential for large and sustainable energy savings in the process.
4. ENERGY ACCOUNTABLE CENTERS (EAC'S)
Prior to implementing any energy monitoring strategy and system, the user should identify their EAC's (energy accountable centers). These are simply the areas the user wants to monitor, generally areas where there is large energy usage and a big potential for savings. This can generally be clearly determined from a site audit.
The EAC's are not limited to one site, but can be rolled out to multiple sites, and the monitoring system should have the functionality to remotely monitor and report on multiple sites should the user have this requirement.
It is entirely up to the user how in depth they develop EAC's, possibly down to individual plant components may be necessary. By way of example, a single site might identify the compressor plant and air distribution system as an EAC, but want to further break it down to specific compressors to assess the performance of individual compressors.
5. THE THREE KEY ELEMENTS IN AN AUTOMATED MONITORING AND TARGETING (aM+T) SYSTEM.
Figure 3. Key elements of an aM+T system.
As can be seen from Figure 3 above, the three key elements of an automated monitoring and targeting system are Metering, Data Collection and Data analysis. These are discussed below.
5.1 METERING
This is the first and most important element, as you need to measure accurately all parameters in the process that you are targeting in order to identify inefficiencies, losses and problem areas. To refer to an old but relevant cliché, "If you cannot measure it, you cannot manage it”. Measurement technology selection is an important step, and the correct technology needs to be identified on a case-by case basis taking into account all the process conditions. Costly mistakes are often made at this point, and a detailed design approach should be taken here.
5.2 DATA COLLECTION
This entails collecting the data provided by your measurement devices and putting it into a format compatible with the user's existing system. If there is no system in place, a suitable proposal is required that fits the users requirement, skill level and infrastructure. At this point, energy conversion and calculations can be done, and in a small operation this could be the end point of the automation, with data being extracted from the system manually for manual manipulation and reporting. This is not ideal as this process is time consuming and lends itself to relying on human error.
5.3 DATA ANALYSIS
This is the final step in a monitoring and targeting system. This step takes the data automatically and generates reports in formats suitable to the specific user/manager concerned. A "one report fits all” approach in not suitable, but specific reports for specific management purposes should be generated (i.e. energy related financial reports for the financial manager, production reports for the production department, technical reports such as equipment efficiencies for the maintenance team etc.)
At this stage the users should now have an automated, real time view and reporting system of the process from an energy point of view, and can now develop strategies to address the energy issues with reliable information. The system also gives a means of determining costs saved and lost related to energy, and give clear payback and return on investment data related to the energy savings projects developed. Real-time alarming of problem areas help reduce losses by rapid reaction to any failures in the plant.
6. AN EXAMPLE USING COMPRESSOR MONITORING
As a start, the user should measure energy usage per compressor, and relate this to the output of the compressor by measuring the air massflow output of the unit. This will give the specific consumption of the individual compressors, as well as the efficiencies. The compressors can then be duty cycled accordingly. This already will result in energy savings by using the most efficient equipment first and the least efficient last. Without a measure of this efficiency installed, this is not possible.
As a rule of thumb, 1 bar pressure drop on an air system equates to around 6 to 7% energy loss on that system. Using this, a simple quick win is to place low cost pressure measurement across filters to check for blockages. Alarms can now be set for the operators when the filter reaches a certain differential pressure indicating a blockage. Apart from indicating the point at which it becomes viable from an energy perspective to change the filters, they will also indicated compressor failures such as water or oil carry-over before this can reach the process and cause damage or losses.
The next step will be to monitor the total output of the compressor house, either by balancing the individual outputs of the flowmeters on each compressor, or by installing a master meter on the compressor house main outlet. The total specific consumption (energy used per kg of air produced) can now be determined for that specific compressor house. From this master data, a mass balance can be done against the specific users on the plant by installing flow monitoring on each individual user area (department). Each individual department can now have their usage profiled and benchmarked. It is important to note at this time that the measurement must be done prior to putting energy savings strategies into place, as this first measure will be the initial "as found” state of the plant, and will be the benchmark profile against which savings strategies further along can then be measured. This profile can also indicate problems on the specific area of plant such as leaks and wastage where there are discrepancies compared to the benchmark. With this "real-time measurement”, these plant issues can be addressed immediately and not at some future date (such as when a periodic leak test is done). The energy that would have been lost without this measurement is now saved. The potential loss that would have resulted without the warning can also be calculated and the loss savings put into reliable monetary terms.
An important step is to now continuously measure as a cycle (we discuss this in the next chapter). The savings strategies can now be "hardwired” into the departmental KPI's, and the department then becomes accountable for its energy usage. In this way, the savings strategies put into place become sustainable, as there is a continuous awareness and accountability at point of use.
A similar strategy can be put into place with other utilities such as steam, gas and water distribution, so we will not go into detail on these specific areas. It is enough to be aware that using the example of the compressor house, other utilities can be measured in much the same manner
7. ENERGY MANAGEMENT AS A CYCLE
Figure 4. Energy management as a cycle |
In the previous chapter, we looked at the concept of Energy Management as a Cycle. Figure 4 above shows this cycle. We have discussed the measurement and data collection process, and getting data into information in chapter 5, as well as the reporting of this (we discuss reporting in more detail later on). The critical issue in this strategy is to ensure that this becomes a cycle. The system we have discussed above (seen in blue in Figure 4) only gives you the information. What you do with that information now determines the savings that are made. |
8. THE MONITORING AND TARGETING PROCESS - WORKING WITH PROFILES AND BASELINES
Figure 5. A typical profile showing baseline and production dependant profiles
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Looking at Figure 5, this is a typical energy profile developed using the aM+T system as described in previous chapters. Once this benchmark is in place, the savings strategies can be put into place and measured for success or failure. It is a good point to start by looking at the production independent areas first (usage when no production is in progress). This is generally as a result of leakage and wastage. These are the easier areas to address, and rapid results can be realised when addressing these. Once all the production independent areas have been exhausted, the strategy can move to the production dependent areas. This generally involves optimization and efficiency improvements in the process and equipment. Again this is continuously measured to determine the success or failure of the strategy with the aM+T system. |
9. TARGET SETTING, DEVIATION ANALYSIS AND PERFORMANCE TO TARGET PLOTTING
Looking at figure 6 right, this displays a typical profile analysis that can be developed using an aM+T system. Once this profile is known, the energy usage at any point on the production curve can now be determined or predicted. This in now the initial energy benchmark to work from (this should be the target for the energy usage on the plant). This graph is developed by measuring the process over a period to develop the plants energy profile (usually over a period of 2 - 4 weeks).
The next step is to now plot the actual usage against the profile on a deviation analysis as shown in figure 7 right. By plotting this deviation (within agreed tolerances as shown by the red limits), any drift from the normal profile is quickly and easily seen. In the example below, the savings shown are as a result of the installation of an economiser on a boiler.
The result can very easily be visualised and measured on this deviation analysis. Once the saving has become stable, the new level or profile now becomes the new benchmark or target to work from. If there was a problem on the plant, the deviation would similarly be visualised, but in the opposite direction. This very quickly indicates the extent and result of plant problems and failures.
The final step is to put the savings/failures into quantifiable terms. This is simply done by plotting the actual performance against the target on a "CUSUM” analysis. This is basically a cumulative sum of the savings/losses made on the plant in kWh or even Rand terms. With this method, a clear, accurate and verifiable payback/cost can be seen on a savings strategy or plant fault. (see figure 8 right).
The result of this whole process is a reliable, accurate and verifiable set of data. The data gives a clear view of the status of the process, the results of savings strategies and the outcome of failures on plant. This can now be used by the management team to develop further savings strategies with and assist them in making educated assessments and decisions rather than speculative ones, as the data clearly indicates the overall picture of the process from an energy perspective in real-time.
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Figure 6. Regression analysis graph
Figure 7. Deviation analysis
Figure 8. CUSUM analysis |
10. CONCLUSION
Energy savings are easily attained, but making them sustainable is the challenge that we face. Using a well structured and supported approach, large energy savings can be achieved. It is critical that the strategy includes a monitoring system that will continuously measure and report on the status of the energy on the process against predetermined benchmarks. A dedicated system will ensure that sustainable savings are achieved by putting the strategy into the KPI's and accountabilities of departments using the monitoring and targeting system. The strategy must be viewed as an on-going cycle, and not mere ad-hoc events that generally do not show long term savings. The approach is simple, but a structured approach has to be followed.
11. REFERENCES
[1] Author unknown: "OIT/Department of Energy: "Assessment of the Market for Compressed Air Efficiency Services; 2001” (online). Available from www.oit.doe.gov.com (accessed 15.01.2010)
[2] Author Unknown: "Tips and advice on specifying efficient steam boilers”, Publisher - Byworth Boilers (online). Available from www.byworth.co.uk/uploads/downloads/Energy_and_Environment-Tipsand%20Advice.pdf (accessed 21.09.2010)
[3] Author unknown: GPG385 Energy Efficient Compressed Air Systems, Publisher - The Carbon Trust UK, London, March 2005
[4] Donald R. Wulfinghoff : Energy Efficiency Manual. Energy Efficiency Press, Wheaton Maryland, 1999
[5] Professor Grobler, L.J, "A Strategic Approach towards Energy Efficiency" Mining and Industrial Energy Optimization Roadshow 2009
12. BIBLIOGRAPHY
Certified Energy Manager Course 2009, Resource Manual. Publisher - Energy Training Foundation.
Energy savings strategies 2009 - a presentation.
Author - C.Gimson. Publisher - Endress+Hauser
12. AUTHOR
Principal Author: Evan Dent holds a National Higher Diploma in Electrical Engineering from Witwatersrand Technikon (now University of Johannesburg) and a PMD in Business Management from the Gordon Institute of Business Science (University of Pretoria). He is a senior member of the SAIMC (South African Institute of Measurement and Control). Currently he is the Business Development Manager at Endress+Hauser South Africa. He has held various positions within Endress+Hauser since 1993 in the technical and marketing disciplines.