In Thika, about 46 km from Nairobi, Charles Mbarire runs Jungle Harvest Ltd, a farm producing herbs for local and export markets. The farm produces basil, mint, rosemary, tarragon and other herbs. Currently it sells the herbs to a local exporter that supplies multiple clients, primarily in the United Kingdom and elsewhere in Europe. In Kenya’s tropical climate the herbs can be grown and harvested weekly all year round. The farm has an integrated drip irrigation system drawing water from a nearby river.
Several years ago, Mbarire heard, via Netherlands-headquartered initiative AgriProFocus, about a series of pilot projects for solar-powered cooling. Numerous requests to work with SCE’s technology came from fishermen, dairy farmers, and meat producers, as well as one from Jungle Harvest.
After an interview and a series of questionnaires, SCE sent an engineer to Jungle Harvest to discuss using the site as a pilot. After some pandemic-induced delay, an entirely solar-powered cold room was installed at the farm in September 2021.
“This has been a very good resource for my business,” Mbarire told pv magazine. “The fresh herbs we sell are highly perishable and need to be stored at a certain temperature to maintain expected quality and shelf-life.”
Once harvested, the herbs are kept in the cold room and then in refrigerated trucks and containers until they reach the consumer. Previously, the lack of refrigeration between harvest and collection led to heavy losses.
“In some cases, we would lose 40% to 50% of the produce – a very big loss,” said Mbarire. “After the cold room was installed, I hardly see any loss. It has transformed my business and created trust between the exporter and our farm.”
Cold room
German company Solar Cooling Engineering developed a cooling technology based on a sustainable refrigerant (R600a) and insulation materials. It relies on thermal storage as ice to limit or even remove the need for an additional battery to keep rooms cold at all hours, with only electricity provided by integrated solar panels. As part of its PV Cool Kenya project, it designed and deployed a cold room based on this technology to help farmers reduce post-harvest losses and create new income streams.
“Unlike other cold rooms that rely on traditional grid-tied direct cooling methods with high energy requirements, SelfChill promotes the use of a modular thermal storage to balance cooling peaks,” explained SCE’s Sonja Mettenleiter. “Cooling units are directly powered by PV panels and optional batteries. The cooling energy is stored in an ice-reservoir (water chiller) that provides cold water to a fan coil inside the cold room. This way, energy fluctuations due to changes in solar radiation or usage of the cold room can be balanced by energy stored in the form of ice.”
Mettenleiter says that SCE chose to apply its technology to the agriculture segment because “it is the most impactful sector for the development of emerging economies.” The project’s business model aims to empower farmers and entrepreneurs and also to train local technicians in installing and maintaining the systems.
In designing the cold room, the project also focused on components and materials designed and assembled in Africa, making repair and recycling much simpler. This also includes substituting typical polyurethane sandwich panels for insulation walls with a more sustainable, natural material.
Off-grid alternative
While Jungle Harvest does have access to the grid, using grid electricity to power a cold room would have proved far too expensive. Another option, to keep a refrigerated truck at the site during harvesting, proved more affordable but was still prohibitively costly with the joint costs of truck rental and the diesel to power its refrigeration unit.
As a pilot project, the cost of Jungle Harvest’s cold room was highly subsidized and includes partnerships with SCE, that want to use it as a demonstration of its product and how well it works, and with Strathmore University in Nairobi, which uses the system as a training ground for its engineering students.
So far, almost two years into the cold room’s operation, Mbarire says he is impressed and has not faced major challenges. Even on cloudy days, he finds the system runs efficiently and produces plenty of ice. The batteries came with a five-year guarantee and will likely be the first part that needs to be replaced but for now they are still working well. SCE estimates that its system has improved productivity at Jungle Harvest by about 230%.
The owners are also happy with lower production costs and improved relations with buyers since the system was installed. “With the cold room, we can easily harvest without a lot of stress,” Mbarire said. “We’re never in a hurry, so long as we know when to deliver, we can manage labor and keep produce in the cold room until it is graded for export.”
Mbarire said he hopes to see further subsidies in place to help small agricultural businesses cover the upfront cost of the systems. “This is the way to go, but for smallholder farmers in Kenya it’s an uphill task getting the resources to install one,” he said. “Such opportunities, if they appear, could go a long way to keeping smallholder farmers in business, and improve issues around food security and nutrition as well.”
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