Tag Archives: energy audit

Earth, Wind, Fire, Water & Tyres


Grey Green recently completed a comprehensive energy audit at one of the largest tyre manufacturers in Africa. Our team investigated all energy and material flows. Excellent savings opportunities were found on:

  • Air compressors, plus compressed air distribution and use
  • Boiler, steam distribution and use
  • Effluent
  • Lighting
  • Materials handling
  • Solid waste
  • Water heating

The sixteen best savings opportunities gave payback periods between immediate (no Capex required, just improved control or maintenance) to ~3.9 years, with the average at less than 2 years. These were also quantified in terms of reduced carbon dioxide emissions and decreased carbon tax liability.

Annual financial savings were several millions of Rands.

The tyre company management shall also be able to use our Scenario Planning Tool to:

  • Graphically compare the savings produced by each savings opportunity
  • Decide when each opportunity should be implemented

Scenario Planning Tool

Grey Green also conducted pre-feasibility studies on various sources of renewable energy:

  • Earth – Biogas, from anaerobic digestion of locally sourced organic matter and biomass as a boiler fuel
  • Wind – Wind turbines opportunities in the region
  • Fire – Solar PV (i.e. photovoltaic) and solar water heating
  • Water – Hydro-electric options available.

As expected, the renewable energy opportunities have longer payback periods than energy efficiency opportunities, but once factory efficiency has been maximised, the only way of reducing energy costs further is by producing one’s own energy from renewable sources.

Come Wine with Grey Green

Grey Green have audited six wineries in the Western Cape during the harvest period over the past few months with another two winery energy audits in progress and a further three in the pipeline.

On average, the energy saving opportunities identified at each site could potentially save the wineries approximately R 370 000 per annum with a promising average pay-back period of 3 years. We also calculated an average of 400 tonnes of equivalent carbon dioxide emissions saved through our recommendations.

Highlights of the proposed interventions included: 

  • Effluent Treatment Optimizations
  • Feasibility Studies for Solar PV
  • Waste-Heat Recovery System design
  • Energy Efficient Extraction System design
  • Efficient Lighting Retro-fit proposals
  • Chiller System Optimizations including. insulation

Interestingly, chillers (cooling/refrigeration) accounted for approximately 40% of the total energy consumption, with the exception of those wineries with a distillery. The distillery accounted for 18% electrically and when converting the boiler fuel into equivalent kWh (using the calorific value of the fuel), the fuel accounted for 94% of the total energy consumption!

Lauren almost overshadowed by grape skins
Lauren almost overshadowed by grape skins


Gabriel- Industrial Energy Efficiency Interventions

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.

EE Spiral

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.

Pie-chart of Savings Breakdown

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.

Distell Energy Audits

We have completed three intensive energy audits at three large distilleries in the Western Cape. This included a month of energy data collection through sub-metering at the departmental as well as the equipment levels to get a highly accurate energy demand breakdown.

The assessment included an analysis of the steam system, including an analysis of the boiler stack flue gases and condensate return. A number of detailed business cases were developed to present energy saving opportunities. It also included an analysis of the existing metering systems and recommendations were made to increase the effectiveness of the existing measurement systems. Finally, a number of behaviour change initiatives were recommended.

Energy Efficiency Savings Realized

Energy & Cost Saving Examples

• Identified R300 000 annual electricity and R500 000 annual coal savings at no/low cost for a large brandy distillery
• Achieved R 800 000 annual savings at a shock absorber manufacturing plant which can be achieved at NO cost.
• Energy management program at two large hotels where we identified 20% savings (amounting to R206 000 per year) using no cost interventions
• Diagnostic audit at a concrete factory where we identified a 5% saving at no cost and a further 21% using interventions with a one year payback. This excludes the additional benefits from reduced demand charges
• Achieved a 10% no cost savings at an office block and identified a further 5% low cost saving
• Identified a 30% saving at manufacturing facility using a medium cost intervention with 2 year payback period

Payment Models & Results Achieved

EE Case Study -Payment Models

• The above 3 Year Total Savings are guaranteed & verified by Eskom’s independent M&V team
• Upfront payment means the client paid for the equipment and collected the rebates
• Financed payment means Grey Green financed the equipment & charged a monthly fee
• Shared savings payment means Grey Green paid for the equipment & took a % of the savings

Feasibility Study & Intervention Examples

• Boiler efficiency studies including flue gas analysis and combustion efficiency where we also assessed feasibility for supplementing coal with biomass
• Simpler interventions such as heat pumps, low-flow shower heads and energy efficient lighting

Diagnostic Audit Results Examples

Caledon Hotel Energy Audit

Grey Green audited the Caledon Hotel & Spa on behalf of Heritage South Africa. An intensive energy audited was conducted over a few months. The hotel is a large complex consisting of the hotel, restaurants, casino, spa and conference facilities. A number of interventions were identified and included in a report to the client highlighting how energy is currently being consumed and outlining possible ways to reduce energy consumption.

Haven Night Shelters Energy Audit

We conducted a detailed energy audit of a homeless shelter for the Haven. This included metering of the incoming supply as well as a detailed assessment of the energy needs for water heating and cooking. Many recommendations were made to reduce the use of electricity through upgrading of old inefficient refrigeration and AV equipment, as well as using heat pumps for heating water and low flow shower heads.

Energy Efficiency Audit & Consumption Profiling

Commodore and Portswood Energy Study – Two intensive energy studies at the Commodore Hotel and Portswood Hotel in the Cape Town waterfront were carried out. This comprised of detailed energy audit and monitoring of the kitchen, hot water boilers and mains supply. This information served to make recommendations for reducing electricity consumption without capital intensive retrofits. Close interaction with the hotel staff was ongoing and a critical part of making sustainable energy savings. Energy efficiency principles were applied, in conjunction with detailed data, and estimated no or low cost savings are in the region of R20 000 a month. Furthermore, feasibility studies for larger capital intensive projects like heat pumps and solar water heating systems were also carried out.