Considerations for Storing Ensiled Rye

Properly planned and designed storage is key to maintaining the quality of your ensiled rye and other biomass feedstocks. Whether storing 10 or 10,000 tons of feedstock, taking these factors into consideration can increase the chances of successfully storing the raw material at the conclusion of the storage period. Here are some areas to consider when developing a feedstock storage and consumption strategy

Design

Accessibility: You'll likely need to access the feedstock throughout the year, so choose a location easily accessible to your loading equipment. This might be near a highway or close to where you'll be using the feedstock. Field-edge storage can work for baled silage if it's easily accessible, take into consideration the type of road and any weight restrictions that might need to be managed for. Always when selecting field entrances allow for easy ingress and egress for the transportation equipment.  When using bunker or pile storage it is best to locate it near the point of processing due to the challenges of moving bulk material.  Most scenarios for consuming the feedstock will require consistent access to a source.  It is important to take this into account when designing a storage site. An end user should consider having onsite storage to have consistent access to feedstock.  A supplier should take into account that a delivery schedule may not occur in an ideal timeframe.  A storage site that is designed to accommodate for accessibility will allow for delivery all season and could be economically incentivized by the end user.

Ground Conditions: Ensure the ground beneath your storage area is well-drained to prevent groundwater from seeping in and causing dry matter loss. The ground will become uneven and possibly start to form ruts as loading and loadout occur.  This will be especially pronounced in saturated sections of the storage area. Permanent storage would likely benefit from a hard surface such as concrete or asphalt, however this may be cost prohibitive. Raised storage pads with tile drainage underneath can be an alternative solution which would minimize excess moisture while moderating costs. Rock is a cheaper alternative to use for a pad. The rock will stick to the bottom of the feedstock so it will make it into equipment and possibly the final product.

Runoff: Large storage areas require special attention to runoff. Properly sloping storage pads to allow for runoff to escape will maintain the pad and feedstock integrity. Also managing feedstock moisture will prevent runoff from the ensilage process.

Pad Size and Oxygen Exposure: Design your storage pad so you can remove enough material at a time to minimize oxygen exposure to the remaining feedstock. This is especially important during warm months when spoilage can happen quickly (within hours). In colder months, you have more leeway (potentially months).

Fire Prevention: If storing feedstock at the field edge, keep the area clear of grass and other flammable materials. For large storage sites international fire code 2808 provides guidance for storage site design. Particularly this entails the distance between stacks or piles to minimize the spread of fire. There are also recommendations for improved accessibility of firefighting equipment in the event of a fire. A supply chain participant should recognize the critical nature of risk reduction for fires. Working with local authorities to develop a response plan will reduce the risk to first responders when around a fire and minimize the amount of feedstock that could burn.

Operations

Plastic Disposal: Plan for proper disposal of the plastic wrap as you remove from the stack or pile. Plastic can blow around the site and become entangled in equipment causing unnecessary damage or enter in the feedstock stream causing process flow issues at the biorefinery. A refuse container at the storage sites and near areas where bales are handled will help encourage workers to dispose of bale wrap or covering as feedstock is removed. 

Protecting the Plastic: Be careful not to puncture the plastic covering your feedstock. Any holes will allow oxygen in and degrade the material.  If a tear and puncture occur it should be repaired as soon as possible once it is identified. Plan to have occasional site inspections to identify areas of concern that can either be repaired or consumed.   

Varmint and Animal Protection: Densely stacked feedstock could become an ideal habitat for varmints like racoons. Severe damage to plastic could occur if varmints are allowed access to the site. The best practice is to minimize the potential habitat by placing gaps in between stacks or access to the areas. 

Non-Spec Material: Plan to have feedstock that will spoil, not meet plant specifications, or broken bales that will need to be disposed of.  This will likely consist of three potential pathways for this material: 1.) Respread on designated areas 2.) Repackage material to transport offsite, or 3.) Dispose of material in landfill.

Community Relations: Often a storage site for feedstock to any scale could be new to many in the community. This will bring about questions and concerns. Transparency will help address a lot of concerns. Addressing many of the points of guidance laid out in this article will help you continue to be a good steward to the surrounding neighbors.     

Equipment: A storage site will require access to equipment that can handle bales. This would likely be a payloader, telehandler, tractor, or skid steer. A large-scale site might require a dedicated machine to conduct maintenance and upkeep around the site. Smaller storage sites could allow for equipment to be hauled in when maintenance or loading is being conducted. 

Consumption Strategy: Identify the highest risk feedstock within the supply chain. Plan to consume this material first to preserve most of dry matter and integrity of the material in its transportable form. A strategy may also encompass plans to further reduce the risk of fire spread by increasing the spacing between the storage pads. Decide how much feedstock to hold over year to year. The consensus in the industry is to have about one third of the total yearly consumed amount on hand. When selecting feedstock to carryover, identify the best storage pads to store the material. Use the lowest risk feedstock in the longest planned storage.

Costs

Equipment: Most handling costs will be associated with transportation of the feedstock. There are handling costs associated with storage due to placing the bale in the final storage location for the year or simply site maintenance. This cost would be figured at $1 per ton. It should be figured that the handling cost increases by $1 per ton each time the feedstock is touched. 

Covering: Either multiple layers of plastic or tarps will be used to create an anaerobic environment for the ensilation process. It will cost $2-3 per ton to cover the feedstock. Placing the feedstock in a stack or in a pile equipment will be required. It will cost around $7 – 10 per ton for the equipment and manpower to pack and apply the covers over the feedstock.

Administrative: Depending on the size and scale of the operation the operating margins will vary. Typically, one should consider a 10% - 20% margin should be applied to these costs to account for various operating and administrative costs. A dedicated storage site may be assessed as an improved area which may also raise the property taxes. 

Real Experiences from Commercial Storage

Past experience from commercial storage has shown that two of the top challenges are site prep for drainage and fire. Poor drainage causes issues with increased dry matter loss and potential safety issues with soft ground under the store feedstock. Fire will cause not only loss of the feedstock but also a community relations challenge.