Afrupro modernized its ammonia chiller system without any capital costs, saving 20% on its annual electricity bill.
Afrupro is a South African fruit-packing company.
In South Africa, companies like fruit packer Afrupro Packers are prime candidates for the cooling-as-a-service (CaaS) business model, a pay-as-you-go scheme that allows end users to install efficient cooling equipment without any up-front capital costs.
This is, in fact, how Afrupro was able to recently upgrade its unreliable, aging ammonia chiller system, improving efficiencies and lowering energy consumption by 20%.
Afrupro Packers does the marketing and packaging of all grades of locally grown avocados and litchi fruits, both in South Africa and internationally. But it found that the maintenance and electricity costs for its ammonia installation were out of control while cold rooms were not maintaining temperature, resulting in product loss.
In addition, during the 2019 season, the glycol tanks were leaking, incurring a cost of more than ZAR2,000 (US$110) per day. After investigating, Afrupro found that old plastic tanks, possibly cracked, needed to be replaced. With the litchi season approaching, a refrigeration upgrade became a matter of urgency.Afrupro wanted the aging ammonia system removed and replaced with a high-GWP (1,825) R407F multiplex system, which is a common solution in the part of South Africa where the company is located (Tzaneen, Limpopo). But following a thorough evaluation, Energy Partners Refrigeration, a South African solutions provider, proposed an outsourced CaaS cooling solution that Energy Partners would finance, own and optimize. The result would be an upgraded ammonia plant to provide better, more reliable cost-efficient cooling with energy savings.
The upgrade involved the installation of a new liquid receiver (including valves and instrumentation), new stainless-steel glycol tanks, refrigerant piping changed to suit the new design, and a full recommissioning. Existing mechanical controls were replaced with a new computerized control system with remote monitoring capabilities.
The upgrade has proven to be a success. “We don’t have any problems with the refrigeration and the cold rooms have never worked as well as they do now – not even when it was new,” said Simon Tattersall, Managing Director for Afrupro.
In addition to saving energy compared to the old system, the upgrade is also beneficial compared to the proposed R407F system. Computer modeling of that system (using an internationally recognized tool, PakCalc) showed 9% additional electricity use compared to the upgraded ammonia plant. That equates to annual savings of 58,000kWh, or 61metric tons of CO2e emissions avoided yearly.
Using a 20% gas leak rate, which is conservative in South Africa, the CO2e emission avoidance due to gas leaks comes to 365 metric tons annually. This gives a total project CO2e emissions avoidance of 426 metric tons annually or 4,260 metric tons over the 10-year contract period.The CaaS contract
The CaaS agreement between Afrupro and Energy Partners determined that the latter provides an investment of ZAR3.7 million (US$200,000) for the upgrade, and takes ownership of the operations of the system for the decade-long contracted period. This includes a comprehensive maintenance program with remote monitoring and management.
Energy Partners has set up a wholly owned subsidiary, EP Investments, as a vehicle for its energy investments. Projects are financed through a combination of 70% bank funding and 30% own funding (equity).
Under the agreement, Afrupro is responsible, on a monthly basis, only for a fixed “availability fee” and a variable “usage fee” based on the refrigeration required. Energy Partners covers the cost of elec- tricity used for refrigeration.Control what you measure
Digital controls and analysis, important in any modern HVAC&R installation, are particularly key in CaaS arrangements, since the provider needs to carefully track and optimize cooling usage.
“This site once again taught us that you can only control what you measure, and don’t assume anything,” said Henk McDonald, Sales Engineer for Energy Partners.
Afrupro’s existing mechanical control system was replaced with an HControl Solutions programmable control system. This included several PLCs (programmable logic controllers) allowing for human-machine interfaces (HMIs) for system and cold-room management. Also added: a Supervisory Control and Data Acquisition (SCADA) platform to record temperatures and allow remote assistance. In order to better comply with export standards and reduce temperature variation in products, additional temperature sensors were installed in the cold rooms.
““We don’t have any problems with the refrigeration and the cold rooms have never worked as well as they do now – not even when it was new,” Simon Tattersall, Afrupro.
Energy Partners’ cooling meter was installed to measure the energy and cooling consumption remotely. With the start of the avocado season so close after completion, there were some problems initially, but with the effective measurement and monitoring in place, these were easily identified and corrected.
The improved system and controls allowed room temperatures to stabilize on the required setpoints. Due to the redundancy built into the system design, no significant downtime was necessary.
Operations are continuing to run optimally and efficiently. Stock losses have been reduced due to monitored temperature control, ensuring further food security in South Africa.And Afrupro is not done. Plans for the next stage of the system upgrade are being finalized, with a further ZAR4 million (US$226,300) investment.