Portable, inflatable storage barn opens up new opportunities in agriculture.
By Lynn Keillor
After making its mark as a manufacturer of portable, inflatable aircraft hangars, employees at Shropshire, England-based Lindstrand Technologies Ltd. learned a new language: the vocabulary of potatoes. “You’d think it was a very dull subject,” says Fred Neale, who works in finance and commerce at Lindstrand. “It’s actually quite scientific.”
Neale began speaking tuber when Lindstrand was approached by Norfolk, England-based Preva Produce Ltd. in late 2010 to create a portable, inflatable storage barn purpose-built for potatoes.
The list of Preva’s requirements sounds daunting: space for 750 tons of potatoes, modular and easily transportable; precise ventilation capacities and temperature control; a door large enough for large machinery and trucks; high-tech controls; adaptable to a variety of ground conditions, including sharp rocks and uneven surfaces; and able to maintain a rigid structure to withstand high winds.
The list didn’t scare Neale, who is accustomed to dealing with extreme parameters for the company’s aircraft storage buildings. Instead, it intrigued him and opened up the company to a completely new market for its inflatable shelters. In a joint venture with Preva, the companies teamed their respective expertise into Airstore Ltd. to design, test and investigate market potential for agricultural uses.
An agricultural hangar
According to Neale, Lindstrand approached the design by using a similar process to its other structures. The company chose a PVC-coated polyester material appropriate for weather conditions in England. Particular to the potatoes, the material needed to block light from entering the building. Following required building parameters, the polyester was welded into panels with baffles, which are connected and inflated to make the rigid structure. The air in the baffles is set at 1.2 to 1.5 psi. The building can go from flat to a fully inflated and functional in a few hours (for the smaller barn) to a work day (the larger barn).
“If you touch it, it tings,” Neale says of the inflated fabric. “It really is very strong. It has to be, because if you get any wind force it has to stay rigid.” The building has no internal structure, but is so rigid that items can be hung from the interior walls.
The result is a building that looks like an inflated pole barn. A large door at one end allows tractors to drive in and out. Fans at the base of either end maintain proper structure pressure in the walls. Additional ventilation at the roofline helps control temperature and circulate air to maintain correct humidity. There is no floor in the building, and the sides attach flush to the ground by using a stake system. Electricity is provided by generators.
Potatoes, Neale learned, need precise temperature (between 45 and 50 F) and humidity control when in storage. “It affects the sugars and glucose in potatoes,” he says, which makes a big difference for french fry and potato chip manufacturers because it affects how a potato cooks. The air-filled walls and ceiling have excellent insulation properties, Neale adds.
Not only does the new storage unit deliver in these categories, Lindstrand also developed an alert system in case something happens that could affect storage conditions, such as a power loss or even a hole in the structure. In case of such an occurrence, a text message alert is sent to a mobile phone so a repair can be started as soon as possible.
A real benefit to the end user is that the structures are not permanent, Neale says. With this model, the storage units are erected in September at or near a farmer’s field. When the potatoes continue on for processing in November, the structures are deflated and stored. This is a substantial cost- and hassle-saver for farmers, Neale says, especially since the structures do not require any special building permits process in England—something that can be difficult when building a permanent barn.
“They can move this from site to site every year, especially with crop rotation,” Neale says. It can be erected by farm staff, and is stored on pallets.
In economic terms, the structure also saves on transportation costs. “The cost of transporting potatoes from the field to a main storage facility is about 10 pounds [$16] per ton,” Neale says. “That’s a 7,000 pound [$11,000] savings.” A permanent building can cost $1.2 million; the inflatable unit costs approximately $160,000.
The prototype was tested in the fall of 2011, but Neale says they all were certain it would work to proper spec. Still, they put it in what would be considered a challenging position: uneven plowed ground covered in sharp flint where winds whipped up higher than 40 knots.
Not only did the structure live up to Lindstrand’s expectations, it also passed the test for Preva. “It all worked out pretty well,” Neale says. “We made some small design changes, but in terms of ventilation, it was absolutely perfect.”
A growing business?
According to Neale, Lindstrand took on the project because it saw a potential new market. Neither Neale nor his colleagues expected the dramatic number of inquiries from around the world. In mid-April, he was demonstrating the shelters to agriculture executives from South Africa, Russia and other parts of England. He’s received inquiries from Austria, China and other global markets. It’s all been word-of-mouth advertising.
“We’re very bullish about it,” he says.
The company has already made an alternative portable shelter, with hay bales as the walls and an inflatable roof for smaller applications or budget-minded customers. This version costs about half what the full-sized barn does. There’s also potential to expand beyond potatoes to other vegetables and fruits, Neale says.
“All we know so far is that it’s been amazing,” Neale says. “It’s just a question of working it through and seeing how it goes. There are so many opportunities in food, and the cost of transportation here is tremendous because of fuel. It makes economic sense.”
As for copy-cats, Neale suspects they will appear. However, he thinks Lindstrand has an advantage. “We have a lot of expertise in manufacturing and it’s not the easiest thing to make,” he said. “ You don’t want it to collapse and ruin the crop. You have to be sure that a manufacturer knows what it’s doing.”