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Southern Cold Storage – smart efficiency

Southern Cold Storage – smart efficiency

By Ilana Koegelenberg
Southern Cold Storage in Johannesburg boasts one of the biggest freon multiplex systems, and thanks to various clever energy efficiency improvements, the power usage in this rental freezer facility is impressively low.

Uwe and Caroline Schmidthaus are no strangers to the cold storage game, having first moved up to Johannesburg from KwaZulu-Natal in 2008. They bought a frozen distribution business when the previous owner emigrated to New Zealand, with Ola being the primary client and a former employer of Uwe Schmidthaus.

However, as the rental price increased annually, Uwe Schmidthaus decided to start looking around to buy instead. They had also outgrown their current premises and the flow of the operation just wasn’t right. “There were no airlocks and it was hard to effect proper cold chain management,” Caroline Schmidthaus explains.

Initially, they had looked around to find an already built cold store, but they couldn’t find what they were looking for and opted for greenfields instead. Having run the operation for five years at this stage, they knew exactly what they required.

So, in 2012, they bought a piece of land in the then new Southside Industrial Park in Wadeville, Johannesburg, and built their new secondary distribution facility, predominantly to service Ola still. About 90% of this facility is used for ice cream. They moved in during April 2013.

This is where they first teamed up with Lutz Refrigeration who assisted in the design of the refrigeration plant. So, when they decided to expand in 2015 and build another facility next door, they knew where to go. They are also in a 50/50 partnership with the property owner of the park, James Ross Stewart, for this development. “We wanted to diversify more into cold storage but we lacked the funds to manage on our own and, therefore, approached James as a partner and investor,” explains Uwe Schmidthaus.

Caroline Schmidthaus did the initial design for the cold store, which was then given to the architects to draw up. All the way through the process, the Schmidthauses were immersed in the process, with regular meetings for all parties involved taking place every two weeks.

The Southern Cold Storage project first broke ground with civils in April 2015, and ran perfectly on schedule with the commissioning of the refrigeration plant commencing in November that year, only eight months later.

“We would attribute that success to a hands-on owner-management approach to monitoring the schedule on a weekly basis with all contractors present, constantly improving and managing potential problems before they arose,” explains Kevin Walter, mechanical engineer at Lutz Refrigeration.

“Having the room up and running before the December rush was crucial to the success of the business,” says Walter.

For the refrigeration design, the number one priority of this project was to reduce operational costs while keeping capital costs within realistic constraints.

Client brief
The basic layout was determined by the land available with a view to storing as many pallets as possible in the available envelope to optimise rental revenue against operating expense costs. To achieve this, mobile racks were used wherever possible together with a small contingent of stationery racks to allow for some flexibility, with picking being allowed for if required. The outcome is that this facility can hold 3 650 pallets within its roughly 25 000m2 volume.

For the refrigeration design, the number one priority of this project was to reduce operational costs while keeping capital costs within realistic constraints. During the design stage, various industry-leading contractors were invited to tender their own specification and design with a brief to bring to the table what they believed would best match these criteria. Quotes were requested from both freon and ammonia contractors with no allegiance to either refrigerant — only a view to compare on the various levels what would best suit a facility like this.

System description
The basic description of this refrigeration system is a 250kW water-cooled freon multiplex system. The multiplex plant is located on a mezzanine platform 8m up off the ground, to reduce the pumping head required to get the refrigerant up to the evaporators. The multiplex consists of four 70hp GEA reciprocating compressors, which, due to the extremely low condensing temperatures of 30°C, can produce a coefficient of performance (COP) of above 2 for a -25°C cold room. Compared with COPs of 1.4 for an industry-standard condensing temperature of around 45°C, this represents a 40% better conversion of electricity into cooling and subsequently a 40% reduction in energy bills.

The multiplex can be run at a lower cooling capacity during winter months if required, thus presenting flexibility to optimise energy usage according to the varying cooling requirements.

The temperature is measured daily and mailed to Lutz and the client, so they always know what is going on. Walter receives an alarm if something goes wrong and, since Lutz still handles the maintenance, he is on site regularly. This dramatically reduces the amount of on-site inspections needed.

The electrician also checks the generator monthly.

Energy efficiency
Additionally, the following other energy-saving features were employed on this project:

  • The cooling tower fans are variable speed driven.
  • Expansion valves are of the stepper type to better control suction pressures and prevent liquid flood over under dangerous conditions.
  • The airlock leading to the freezer is dehumidified down to as low as 20% humidity via a Bry-Air chemical dehumidifier.
  • All compressors are equipped with ABB soft starters to reduce peak kVA draw under start-up.

Greenwave installed a grid-tied 123kWh solar system, which makes use of 380 Canadian-supplied solar panels feeding into a Schneider inverter system. The solar system does not make use of battery storage and as such, the power that is created must be used or else it is fed back into the grid with no financial reward. Therefore, careful collaboration between Greenwave and Lutz Refrigeration was required to optimise the efficiency of the plant, energy usage, and correct temperatures.

The payback period on the solar installation is about four to five years. Going the battery route would have doubled this period.

The final electrical innovation that has been incorporated into this facility is a power factor correction system supplied by Schneider, which increases the power factor on site from the standard 0.85 up to 0.97. This relatively unknown innovation is translating into a direct saving of more than 5% in electricity.

Because the brief to the contractors was for them to propose their own designs, there were no issues with conflicts between consultant specifications and contractor offerings. The contractors used had all been involved in cold storage projects like this for decades and when allowed to put their best foot forward, they certainly did. “On a whole, the atmosphere was very upbeat, collaborative, and positive during the project,” explains Uwe Schmidthaus.

Electrical usage
When compared with some of the more traditional and dated systems around town, there is no doubt that this plant is more efficient and will leave less of a footprint on the planet in years to come, explains Uwe Schmidthaus. He often compares this facility with his other business, Cool Runners, which distributes various frozen products in Johannesburg. Cool Runners has a storage capacity of 950 pallets, in comparison with Southern Cold Storage’s 3 650 pallets. Uwe Schmidthaus points out that in February 2017, Southern Cold Storage only used 80 000kWh in comparison with Cool Runners using roughly 75 000kWh in the same month. This gives Southern Cold Storage a competitive edge as electrical tariffs continue to increase.

“We are very happy with how this turned out,” explains Uwe Schmidthaus. “We are able to operate smartly and thereby offer our clients a good service at competitive rates.”

Future plans
This cold store is phase one of three phases that are planned, with phase two being a carbon copy of the first one. The building plans have already been approved for this. Phase three will be a dedicated chiller for clients who want both frozen and chilled goods stored. But for now, the economy isn’t exactly suited to expansion.

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Southern Cold Storage

Click below to read the July/August 2017 issue of Cold Link Africa

CLA JulAug 2017



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