Ostrich leather tannery's cost and energy savings quantified after two-and-a-half years of operation with solar

Cape Karoo International (CKI), is the result of a merger between Klein Karoo International and Mosstrich, and is the world’s leading producer of ostrich leather, feathers & meat products with our tannery division boasting an 80% global market share in its supply of ostrich leather. Despite this prestige, our responsibility towards sustainability remains. In fact, ever more so. With our dependence on fossil fuels ever increasing, we decided to seek opportunities for improving on the energy security of our business.

The decision to install a 600m² solar thermal plant to supplement the heating system at our Oudtshoorn tannery was an easy one, and for the past two and a half years, solar thermal has provided for 55-60% of our low-temperature heating requirements.

The system was commissioned at the end of 2018. During 2019, our first full year of operation, our solar thermal system produced 450 274 kWh of solar heat energy, of which 430 656 kWh was fed into our process. This allowed for a saving of 43.6m³ of light fuel oil (processed crude oil), resulting in a saving of R413 269.42 excluding VAT in that year. The savings in year one, proven to us through measured data by CRSES, exceeded our expectations, bringing our expected 7-year ROI closer to that of 6 years. The lockdown’s imposed in 2020 as a result of COVID19 naturally meant that we weren’t able to utilize some of this free energy (nor any of our traditional fuel for that matter). Thankfully, however, E3 Energy’s solution included two vertically discharging dry-coolers that engage when the system reaches its maximum set-point, preventing overheating by blowing excess heat off into the atmosphere.

The solar thermal system was supplied with ease of monitoring, maintenance and management in mind. Data from all the relevant points around the system are recorded continuously and have been presented to us periodically for review since the system’s first commissioning. E3 Energy has also given us visibility of the system by providing a live dashboard, accessible from the browser on our computer or even our mobile phones, which gives our technical staff a real-time view of the temperatures being delivered to our process. This dashboard has been tremendously valuable in us being able to control our internal processes, making sure that we get the most from our investment in the solar heating plant.

The 600m² solar array is split into two 300m² collector fields, which are controlled independently by two separate solar charging stations. To the best of our knowledge, these solar charging stations have always kept the solar buffer storage at a temperature sufficient to supply the 65°C temperature required by our process. The solar heat storage has also been split into two separate parts. There are two 20 000L tanks that operate in parallel but which are plumbed in such a way that either one of them could be used in isolation in the event of a problem with one or the other.

Despite originally questioning this “halving” in E3 Energy’s system design, the ability to compare the performance of one half of the system to the other has proven very valuable. To date, two-and-a-half years after commissioning, one performance variance was noted between the two solar arrays & two tanks, which turned out to be the misreading of a sensor that had become dislodged. Once this sensor had been reinserted fully into its pocket, there proved to be no performance difference after all.

The other benefit to E3’s design is that should one half of the system have an issue for some reason, the other half could remain fully operational until the other half has been resolved.

All in all, the system has shown itself to be a good investment for our business.