Alternatives to Traditional Silo Designs

The benefits of a horizontal system are well worth considering for your next storage project, especially for multi-product operations.
By Joel Dulin | September 04, 2019

We understand the advantages of vertical silos: they allow people to store goods vertically with a limited footprint. They provide first-in, first-out turnover of material. They have thus been a go-to storage solution for some 3,800 years. But they’re not without drawbacks and limitations, the recognition of which has led to the development of alternative storage methods for those with different needs. During the past century, these solutions have become increasingly popular because they eliminate many of the issues associated with vertical silos.

Disadvantages, Limitations of Silos
Among these issues, perhaps the most obvious is cost. Vertical silos require a large investment, the depreciation of which will last decades. Adding to that expense is insurance, an air permit (if needed), a building permit, and tall conveyors or elevators to bring material to the top of the silo.

Besides cost, vertical silos do not allow manufacturers to divide storage. One silo stores one product. While this may be sufficient for a manufacturer that plans on producing only one product, it limits those experimenting with coproducts or who plan on expanding their line of coproducts, as silos cannot be expanded. Manufacturers must therefore estimate future production needs when sizing a silo. If they overestimate their needs, they will oversize the silo and waste money. If they underestimate, they will have to construct more silos. Thus, if a manufacturer wants to scale back a product, add additional products, or ramp up production over time, silos are not ideal.

Adding to the disadvantages of vertical silos is safety. Although rare, deadly accidents involving silos still occur. These accidents typically involve a worker who is trying to break up a bridge or rat hole. Flow issues can be avoided by installing cannons or other devices to break up the material, though for certain goods, the material’s tendency to knit makes a silo an ineffective storage solution.

Other potential issues with silos include repair—when the reclaim system fails, it is all but impossible to repair it while the silo is full—the inability to mix materials upon output, and a lack of redundancy.

Horizontal Storage Systems
Two alternative systems that address these issues are containers and horizontal silos, also called bunkers or low-level silos. Because these terms mean different things across industries and regions, this article will refer to both containers and horizontal silos as horizontal silos and will refer, specifically, to those equipped with moving floors.

Horizontal silos are popular alternative to vertical silos because they offer cost savings and greater flexibility. They’re best for small to medium storage requirements, though large capacities are certainly possible with such systems. The downside is that they require more ground space.

Many of the disadvantages and limitations of vertical silos are addressed in horizontal systems. Financially, producers have more options to limit their expenses. Many horizontal systems are modular— containers can be stacked and stored side by side, and buildings can be equipped with moving floors one section at a time and expanded. For producers, this means they can invest in the storage they need for their current requirements, and only add additional storage when they need it in the future. Producers also save money on material handling systems, as there isn’t the need for tall conveyors or elevators.

With systems that involve moving floors in buildings, producers have the option of converting an existing building into storage space. In doing this, manufacturers not only forego the cost of a new building structure but costs associated with maintaining a wheel loader (and the damage incurred during its operation) used for loadout, as the moving floors automate this process.

With container systems, producers have the benefit of an increased depreciation rate, as containers are machines, not fixed assets. If the containers are moveable or built on a trailer, depreciation rates may further increase.

Other advantages match one-to-one with the limitations of vertical silos: storage can be divided, horizontal systems allow for redundancy, they don’t bridge, and they allow for mixing material upon output. Personnel can perform maintenance on key systems while the horizontal silo is full, and they can repair hydraulics, for example, even while the unit is active so no downtime occurs (assuming the hydraulics are set up to run independently).

If you need to store a large volume of goods and limit your footprint, a vertical silo may still be your best choice. But the benefits of a horizontal system are well worth considering for your next storage project.

Author: Joel Dulin
Marketing Manager, BE&E