The case study presented here is based on an automotive parts manufacturing plant in Western Cape. The high level energy auditing process is shown below in various possible stages. The figure also highlights the potential for increasing savings that can be achieved at each stage. Subsequent stages can usually be partially funded by the savings achieved in the predecessor stage so the capital outlay is kept to minimum and within our client’s budget while creating a positive savings spiral. The offering can also be tailored to include only the selected stages that meet the client’s requirements.
After the ESCO (Grey Green) conducted an on-risk diagnostic energy audit at the client’s plant during 2012, multiple energy saving initiatives were identified and recommended in detailed business cases. The client preferred a shared-savings business model in which the interventions were financed by the ESCO and then paid for as a percentage of the verified savings over a fixed and agreed period. These payments occur only after the project installations have been completed and as savings are realized. The client therefore takes very little upfront risk, does not need to wait for and/or go through any major CAPEX approvals or budgeting cycles and has a positive cash flow from day one.
The first three interventions that were implemented were at absolutely no upfront cost to the client. The client is currently saving an estimate of 1.5 million kWh hours per year. The average annual demand savings thus far are 170 kW. The actual cost to the client thus far has been approximately R2600/kW saved, all paid for from their monthly savings. The high bay lighting retrofit utilized the ESKOM Standard Offer Programme rebates while the fluorescent lighting retrofit utilized the ESKOM Standard Product Programme rebates. The compressed air system optimization is currently in progress. The total savings are shown by intervention type in the diagram below. The interventions are provided with performance guarantees, pre- and post-installation monitoring as well as a maintenance plan which ensures that all savings are sustained.
Future interventions planned at this plant include the introduction of Variable Speed Drives (VSDs) on cooling towers, intelligent control of extraction fans, motion sensors for lights, efficient heating and cooling systems for process baths and waste heat recovery. Once these interventions have been completed, there is also the potential for embedded generation using a grid-tied rooftop solar PV system to further reduce consumption. The client shall also benefit from various manufacturing sector incentives such as the Manufacturing Competitiveness Enhancement Programme (MCEP) for assistance with funding these interventions in addition to already having accessed the ESKOM rebates to subsidize their projects. Grey Green has now also been requested to facilitate similar intervention projects at the other divisions within the entire group of companies.
Whilst all the interventions result in substantial savings and reduced demand charges for the client, they also improve the competitiveness of the client’s core business, reduce their carbon footprint and reduce any potential carbon tax burden.