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Flender/Flender Gear Units/Helical gearbox H2

5-2 Table 5-1: Financial Comparison of Feasible Aeration Energy Conservation Measures Units Using Existing Surface Aerators Replace Existing Surface Aerators Optimized Process & Current Aeration Control Automated Aeration Control FB Cascade NH 4+/DO1 FBDA Hybrid Aerator/Mixer FB DO FB Cascade NH 4+/DO FF FB NH 4+ on DO Control FB Cascade NH 4+/DO Estimated Project Costs Capital Costs 3,9 3,5,8 3,6,3 3,7,8 NCA Engineering Costs2 1,7 8,9 9,0 9,2 Total Project Costs 0 5,7 4,4,8 4,5,4 4,6,0 0 Annual Electricity Use Reduction Consumption MWh/yr 3 5 7 8 8 9 Demand 3 kW 1 2 3 3 3 3 Carbon Reduction 4 /yr 3 5 7 7 8 9 Annual Savings Consumption /yr 3,5 4,6 6,6 7,5 8,3 9,7 Demand /yr 0 Total Annual Savings /yr 3,5 4, 6 6,6 7,5 8,3 9,7 Estimated Simple Payback years 0.0 1.1 6.4 6.1 5.8 NA Notes 1. Costs of VFDs not included 2. Engineering costs assumed at 2% of capital costs. Engineering costs do not include advanced process modelling costs. 3. Demand reduction cost savings were not evaluated 4. Carbon reduction based on 0.9 kg CO 2 /kWh generated. Carbon reduction costs savings were not included The following is noted from Table 5-1: Optimised control of the plant does not require any capital investment and will potentially yield immediate annual aeration energy consumption cost savings of about R3,0 The payback period for upgrading to automated cont rol is about 1 year. It should be noted that the cost of installing VFDs on the aerators could not be assessed during the study and was therefore not included in the analysis Although replacing surface aerators has longer pa yback periods, it yields the highest savings which will be realised after the payback period ranging from 5.8 to 6.4years. 5.7.5 Other Benefits and Impacts of Implementing Aeration Energy Conservation Measures The additional benefits of implementing aeration ECMs that have been evaluated through detaile