Non-Energy Benefits Brought by the Use of Variable Frequency Drives in Pump and Fan Applications
Serna Tamez, A.
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Energy efficiency is one of the most cost-effective ways to enhance security of energy supply, to boost businesses’ competitiveness and to reduce the environmental burden of the energy system. Despite of its relevance, an energy efficiency gap has been identified in the industry. Highlighting non-energy benefits (NEB’s) appears to be an effective approach to curtail this gap and attract the attention of firms. NEB’s can overcome barriers to implement energy efficiency measures by relating them to the core business and competitive advantage of a company. Special attention must be given to the industry sector due to its large energy requirements. Fixed-speed electric motors represent the main electricity users at industries. About two-thirds of the motors drive pump and fan applications which do not need constant motor speeds. For this reason, a great potential of energy benefits (EB’s) can be derived from implementing Variable Frequency Drives (VFD’s). VFD’s are electronic controllers that vary the speed of the motors to meet specific load demands. This thesis investigates the NEB’s and the profitability potential that VFD’s can bring in pump and fan applications at the industry sector by following a three-phase method. First, the benefits are identified and validated through surveys conducted to professionals in the field of VFD’s. A descriptive list including the specific NEB’s, their citation number in the included literature and their contribution to competitive advantage concept resulted from this phase. This list showed that “Improved process control”, “Improved quality”, “Decreased noise”, “Reduced tear and wear on equipment machinery” and “Reduced emissions” and the categories “Operation and Maintenance” and “Production” are the most frequently cited NEB’s in both scientific and manufacturers literature. Next, the extent to which the NEB’s can be quantified is evaluated. Two NEB’s, “Reduced GHG emissions” and “Extended lifetime of equipment” resulted to be quantifiable and applicable to all pump and fan installations as an ex-ante evaluation. A theoretical study case is thereafter presented to show how the quantification of these benefits can increase the profitability of an energy efficiency investment. This evaluation is made by comparing the payback period (PBP), net present value (NPV) and internal rate of return (IRR) indicators to the values obtained from only accounting the EB’s. Results showed that the economic benefits of the ex-ante NEB’s assessed are greater in countries with the combination of lowest electricity prices and highest CO2 emission factors, in processes with slightly reduced speed requirements and in larger motors power ratings with insulation classes A or B. Finally, the calculation method used to assess the benefits is structured and described. A spreadsheet-based model compiling this calculation method is developed as an outcome of this research. It quantifies the EB’s and NEB’s applicable to all pump and fan installations. This model provides a transparent method for quantifying benefits and works as an ex-ante tool to assess VFD’s energy efficiency projects at firms. Although the quantification and profitability potential of NEB’s as an ex-ante is limited as it depends on a number of variables, or events unable to predict, the qualitative findings of this research provide favourable arguments for the implementation of VFD’s in the industry sector. Moreover, by highlighting the advantages of VFD’s, this thesis aims to increase the awareness of governments and standardization bodies to develop missing standards and regulation policies regarding electric motor drive systems.