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Managing Energy Usage in Apple Cold Storage with A C Hulme and Sons

Updated: 6 days ago

Smiling man (Tom Hulme) in a light blue shirt standing among apple trees with green leaves and apples in the foreground, creating a cheerful mood.

A C Hulme and Sons, a Kent farm, led a collaborative project supported by Growing Kent & Medway to tackle apple cold storage energy costs. One of our medium-sized grant programmes funded R&D using AI and sensors to test Demand Side Flexibility (DSF), providing vital data to help the horticulture sector move towards net-zero.

At A Glance: Project Quick Facts

The Challenge: The High Cost of Apple Cold Storage

Storing apples is a high-energy, high-cost operation. To provide UK-grown fruit year-round, growers rely on controlled atmosphere stores, which are essential to maintain fruit quality, but consume vast amounts of electricity. This is especially true during the autumn harvest period, when removing residual heat from the field doubles the energy demand.

For Kent growers like A C Hulme and Sons (ACHS), rising energy costs are a major threat to profitability and a barrier to meeting net-zero targets. The problem was a lack of data: with many different store designs in use, no one knew exactly where the energy was being wasted – on fans, CO₂ scrubbers, nitrogen generators, or refrigeration pack compressors.

The Innovative Idea: Using AI for Demand Side Flexibility (DSF)

ACHS recognised the solution lay in these data. They proposed a project to apply cutting-edge technology – real-time sensors and artificial intelligence (AI) – to the traditional world of apple storage. This was a true partnership innovation, bringing together growers (ACHS, Avalon Fresh), tech specialists (GridDuck, Stemy Energy), and refrigeration experts (JD Cooling).

The core goal was to test the commercial value of Demand Side Flexibility (DSF). This means intelligently turning off refrigeration during peak-cost times (e.g., 4-7 pm) and running it when electricity is cheaper. But the key question was: could this reduce costs without harming fruit quality?

The Approach: Testing Temperature Fluctuation at the Produce Quality Centre

The 8-month project deployed energy sensors across commercial stores on three farms, allowing the team to assess detailed consumption patterns for every component. At the same time, controlled trials began at the Produce Quality Centre (PQC), part of the Natural Resources Institute, University of Greenwich, and co-located with Niab at East Malling.

At the PQC, smart devices from Stemy Energy were installed to remotely manipulate cooling cycles. The team tested turning stores off for 1-4 hours and modulating temperatures (e.g., from 0.5°C to 2.0°C), while meticulously monitoring the impact on fruit temperature and quality.

The Results: New Best Practice for Energy-Efficient Cooling

The trials successfully proved that DSF is a viable strategy. When stores were turned off for 1-4 hours, fruit temperature increased only marginally (from 0.5-0.7°C to 1.0-1.1°C). Fruit quality in the modulated stores was found to be comparable to control fruit stored at a constant temperature.

The project also uncovered a critical new best practice recommendation. When restarting cooling, fans must be delayed 5-10 minutes. If not, they circulate warm air from the header tank, causing a temperature spike that this innovative R&D showed could be avoided.

Looking Forward: Rolling Out Monitoring Across the Farm

While conclusive proof that modulation doesn't harm fruit quality requires multi-season trials, this project has provided the valuable pilot data needed to pursue a larger, UKRI-funded project. The findings have already been shared with growers at major industry events, including the BAPL Technical Day.

For ACHS, the results were immediate. The data revealed energy disparities between their stores, giving them the confidence to invest further in monitoring to eliminate inefficiencies. As Tom Hulme stated: "The outputs have given us the confidence to increase energy monitoring across the business to improve efficiency in our operation."

Innovation Spotlight: Demand Side Flexibility

By securing a near 1:1 ratio of private to public investment (£49,786 to £49,654), the project demonstrated strong private-sector commitment. This significant co-investment ensured the project had a robust budget and that all commercial partners were fully invested in the outcome.

Crucially, the project was designed for commercial scalability from day one. The technologies and protocols developed at ACHS were not unique to one farm; they were designed to be applied to apple stores across Kent and the wider UK. This high potential for replication demonstrated that the findings could be used to develop similar energy-saving systems for other cold storage crops, ensuring a long-term, regional impact.

ACHS understood the challenge of apple storage, but they knew they needed specialist partners to develop a viable solution. The consortium brought together the necessary expertise: GridDuck provided the sensor technology, Stemy Energy delivered the AI and controls, and JD Cooling brought the critical refrigeration engineering knowledge. This diverse partnership showed the project had the technical depth and operational understanding to succeed.

How To Do Innovation Well

What makes a good innovation project? We evaluated over 70 projects funded by Growing Kent & Medway to compare the characteristics of great innovation. An interactive dashboard is available to highlight these key features.

Our Support: Facilitating a High-Tech Consortium

This ambitious R&D project was supported by one of our medium-sized grant programmes, which provided £49,654 in funding. The support was essential for bringing together the diverse consortium of growers, scientists, and tech start-ups.

Tom Hulme concluded: "The project brought together some new partners not previously known to A C Hulme and Sons, who shared new approaches to monitoring and manipulating energy use... it is unlikely we would have been able to get the partners to work together with the same degree of co-operation without Growing Kent & Medway funding."

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