Category Archives: Renewable Energy

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.

Bonnievale 75MW Solar Farm

Grey Green was appointed to assist the project developers with the topographical modelling of the planned 75MW Solar PV plant layout onto the existing digital elevation model. This included high-level plant designs and 3D sketches of final appearance on the actual landscape near Bonnievale, which shall be used in the EIA process.

Rooftop PV System for Triocon

Grey Green has recently been awarded a 10kW Rooftop Solar PV project by Triocon Consulting Engineers on the extension to their office building in Century City. The major components used for this installation were Solar World PV panels, an SMA inverter and a Schletter roof mounting structure. The installation has now been completed with commissioning to follow once the balance of the construction works is complete.

Sibongile Children’s Home PV System

Sibongile installation in progress    Sibongile installation in progress

Grey Green was appointed by Project 90 X 2030 to install a 6kW grid-tied Solar PV system at Sibongile Children’s Centre in Khayelitsha. The system is designed to currently not feed back into the grid.  It is expected to cover at least 30-40% of the centre’s daily energy consumption. Top quality panels and inverters were selected to ensure the longevity of the system.

Feasibility Study for 1MW & 600kW Rooftop Solar PV

Grey Green’s assessment dealt with each of the client’s 10 buildings at different sites around the country as follows:

Perform detailed electricity consumption assessments,  determined each building’s electrical reticulation boundaries, performed structural assessment of the roof structure of each of the buildings with respect to its ability to accommodate the anticipated wind loads imposed by the fitment of a PV system; performed a site assessment of each building roof with regard to the likely impact of shading, space available and ease of access on the production and maintenance of the system.

Arising from those assessments, we proposed with detailed specifications and budget estimates, the largest yielding PV installation possible, stating R/kWh given a 25 year lifetime for the plant. We also prepared a yield assessment for the proposed PV Plant in terms of solar irradiation and electricity production. Our financial analysis presented the simple cost effectiveness based on the capital cost, operating cost and value of the offset electricity savings over the system life span assuming instantaneous embedded consumption and using the tariff applicable to the building as well as payback period.


Feasibility Study for 11.6MW Solar PV Plants

This study was conducted as part of a due diligence exercise for a client who was interested in investing in 3 separate projects spread across SA, and developed for the Small Scale IPP bid round. Grey Green completed a high-level concept design and costing exercise as part of this feasibility study in order to enable our client to determine whether the project was feasible, both in terms of the total EPCM costs as well as the long term returns from the PV plant’s generation over its 25 year lifespan. This project was completed with the assistance of our Spanish partner DISEPROSA.

Feasibility Study for Piggery

The objective of this study was to assess the feasibility of a number of renewable energy interventions that could reduce the piggery’s dependence on the electricity supply. The piggery buildings and abattoir were inspected with the goal of identifying opportunities to reduce electricity consumption by making use of existing waste being generated by the process. This includes the water being used to clean
the piggery, as well as the waste being generated in the abattoir. Furthermore, opportunities to make use of other renewable energy technologies as well as reduce wasted electricity through efficiency measures were also investigated and presented to our client.