A sophisticated waste-to-energy system had the potential to slash energy costs for a Bordertown oat manufacturer, but it required specific infrastructure – a live-bottom silo.
Blue Lake Milling, an oat and grain manufacturer located in Bordertown, South Australia, processes around 24,000 tonnes of oat husk as part of its production process each year.
The oat husk, created as a by-product of the process, was sold to stock feeders to be used as bulk filler for feed pellets.
Blue Lake Milling is a 24-hour, five-day-a-week operation, and was feeling the sting of increasing energy prices. In 2017, the monthly power bill for the company’s operation in Bordertown was $50,000. By 2018, that number had reached $80,000 a month.
As a result, in 2018, the company’s chief executive officer Ben Abbot found a better, more valuable way to use the husk.
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The solution was to use a process called anaerobic digestion, which involved placing the discarded oat husks in a tank of water with special bacteria to create methane gas, which could then be channelled into an engine to generate power.
“With the system that we are looking at, we would generate more than enough power ourselves; two thirds of it would go to the mill, and the remaining third could be put back into the grid, which is an added bonus,” Abbot says.
“It’s proven technology, and a West Australian company has also successfully adopted a similar system to process food waste.”
Bioenergy company Biogass specialises in providing anaerobic digestion systems for commercial and industrial waste and was selected to upgrade the company’s Bordertown facility.
As part of the scope of works, Biogass required a new silo to be constructed. Oat husk is made up of fine particles and requires specialised equipment to avoid bridging or moisture hardening from interrupting the flow.
Biogass reached out to Allied Grain Systems, a provider of grain silos, conveyors and steel structures to build the silo, and to TUNRA Bulk Solids to provide a material analysis and design guidance.
Kristian Soini, Allied Grain System’s Project Manager, says that a live bottom silo was required for the project.
“In a regular silo, gravity is used to move the product out and onto a conveyor below. However, because of the flow properties of the oat husk, that simply wasn’t viable,” he explains.
“Instead, we used a live bottom silo, which has a twin auger at the bottom that can take the material out effectively.”
The silo was designed with a specific opening on the silo flange, with a conical hopper angled to allow for material to flow most optimally.
Allied Grain Systems, based in Young, New South Wales, then set about installing the silo at the Bordertown site, around 900 kilometres away. The company operates its own truck fleet and was able to use its resources to coordinate the build.
At the site itself, space was at a premium. Usually, the roof would be built into place and rings would be added using hydraulic jacks, building it from the top down, before it is then lifted into place. At the site, there was only one concrete slab available for construction, which required additional crane work to ensure the silo was stable and secure at all times during the construction.
Soini says the project was the first time the company had built a live bottom silo. He says the installation went well, with no surprises or hiccups.
“We had talked about building a live bottom silo for a while, but had never actually done it before. We were not familiar with the product, and thanks to TUNRA’s report, we were able to understand the product and how it behaves,” he says.
“While we specialise in grain silos, if we are able to get enough data on something to build knowledge, we can create purpose-built solutions.”
One of Biogass’ main reasons for selecting Allied Grain Systems was the company’s transparent and open communication style.
The two companies had previously not worked with each other before and to build trust, Allied Grain Systems endeavoured to be as communicative as possible during the project design, through to quoting and the installation.
Soini says Allied Grain Systems strives to be as transparent as possible, letting their business partners know what they do and don’t know.
The company finds this approach useful when providing turnkey silo solutions. Allied Grain Systems first learns what its clients are looking for from a project before designing a product flow diagram, performing site inspections, and collaborating to decide what the best course of action is going forward.
Soini says building these relationships is critical, as it’s not something that can just be bought with money.
“People want to deal with people they like and can trust. That’s something that requires care and nurturing,” he says.
Part of this is supporting customers after installation. Allied Grain Systems offers a one-year warranty across all of its products and can provide support if there are any technical issues.
“We always provide support, especially for remote areas,” Soini says. “One of the best ways of doing that is delivering a project so well that we don’t have to go back.”