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Making vertical farming viable

23 July 2017

Control Engineering UK looks at the role that machine control has played in helping make vertical farming a commercially viable option. 

Vertical farming is a technique which involves growing crops in trays, stacked vertically. The technique can offer many benefits. It uses less water, pesticides, fertiliser and has lower labour costs than traditional farming methods. Food can also be grown closer to the point of use, in urban settings, or areas not normally suitable for agriculture. 

Henry Aykroyd, CEO at vertical farming developer, Intelligent Growth Solution (IGS), explains the advantages of the technique: “Vertical farming allows us to provide the exact lighting and environmental conditions necessary for optimal plant growth. The collected growth data ensures the technique is repeatable in any location, at any time, providing fresh, consistent crops with less wastage than other techniques.”

The main sticking point that has halted the widespread adoption of vertical farming is that it requires a great deal of energy. Even though vertical farming uses power efficient LED lighting, a way to lower the energy costs to a level that would make it commercially viable has not been found. 

IGS has developed several ways of getting round these commercial obstacles by increasing the adoption of automation technology, smart lighting and flexing with the grid.  

IGS was founded around the idea of a unique growth tower as a machine concept, based around a vertical stacking system. The tower design features 64 4m x 1.6m growing trays. The stacking system-based tower design is highly scalable, as each tower would have its own control system. All serviceable parts are contained within the first 1m of the tower and access to the crops is granted when the tray leaves the tower which negates the need for staff to work at height. 

Initially, two prototype towers were built. The integration of the stacking system, LED control, hydroponics and power systems was complex, especially since the design had to allow for new features and towers to be added when necessary. 

Omron helped IGS to create a future-proof control system from the ground up, with enough flexibility to accommodate any changes in the prototype designs. The control for the lighting, cooling and hydroponics systems had to be completely integrated into the system. 

The stacking system, lighting, hydroponics and other components in each tower would be controlled directly by an Omron Sysmac machine controller which is able to output secure data directly to a SQL database to add or manipulate data. In the vertical farming system, the controller communicated straight to the cloud. The ability to connect the control system to the cloud allowed the towers to operate without the need for an enterprise IT system, further saving on the cost and complexity of the overall system.

Elimination of enterprise IT layer 
“Omron Sysmac controls and monitors every aspect of the system in real-time, as well as eliminating the need for the whole IT layer,” said Dave Scott, technical director at IGS. “This implementation cuts out many traditional causes of downtime and failure. We had a power cut recently and once power was restored, the factory returned to normal with no UPS systems, no data corruption and no human input required.”

Communications were implemented using both control I/O over EtherCAT, and SQL data over Ethernet/IP. This dual protocol approach allowed the optimal communications system to be used for the tasks that were most appropriate. The control I/O took care of the system sensors and lighting with the same EtherCAT network also handling the motion control element.

The Omron hardware was supported by Sysmac Studio configuration software. Sysmac gave IGS a single flexible platform that could be used to develop the control software, validate it, and then control and monitor the towers. Changes can be made remotely via VPN to the system and new features can be supplied when the company needs them in the future. 

The completed prototypes allowed IGS to work on overcoming the energy problems that had made earlier vertical farming attempts economically unviable. Initially itlooked at how to make the LED lighting more efficient while giving the features the scientists desired. The company implemented a new technique to wire the LEDs directly from the power supply. This cut the power consumption of the LEDs dramatically, without losing any control. Tests on the system show the LEDs have energy efficiencies up to 90% right down to 20% load. 

Even though the new design made the lighting more efficient, the overall energy consumption was still too high to be commercially viable. Since almost every aspect of the growing cycle is not time critical, IGS can flex with the grid in real time, resulting in lower electricity costs to operate. The control system can automatically coordinate growing cycles with the periods of time where the energy supplier is under or over capacity. This technique further decreases the electrical costs. 

“We are currently working on real-time crop sensing, which will enable the crops to communicate directly with the lights, ensuring we only create light the plants can use,” concluded Scott.


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