Woodyards can be classified into three main categories: automated, manual, and semi-automated. Deciding on which approach best suits a facility’s needs requires careful evaluation of several criteria:
- Volume – the amount of fuel storage and throughput
- Size – the footprint for the woodyard
- Budget – capital outlay vs. operating costs
- Climate – predictable weather conditions affecting operations
- Regulations – federal and local rules regarding emissions, dust, ash, noise
As the two extremes in the trinity, the fully automated and manual approaches can be contrasted as follows:
|Criteria||Automated System||Manual System|
|Budget||High startup capital costs. Low operational costs.||Low initial capital outlay. High operational costs.|
|Size||Larger footprint.||Smaller footprint.|
|Volume||Works for any size facility.||Practical only for smaller facilities with limited throughput.|
|Climate||Suitable for any climate.||Most commonly used in warmer climates.|
|Regulations||Fully enclosed approaches for dust and noise control possible.||Difficult and costly to enclose.|
Automated Fuel Feed Systems
The criteria used to evaluate whether a fully automated or manual approach to woodyard design is best for a facility obviously depends on the project. For example, a major university in the Midwest recently opted for full automation based on fuel-feed requirements and weather conditions. The university’s system needed to be capable of receiving up to 60 tons of biomass per hour and then deliver nine tons per hour to two boilers. The woodyard had to be fully enclosed due to harsh winter conditions and regional dust control requirements. Given these criteria, automation made sense.
Manual Fuel Feed Systems
Manual systems are typically best for plants that don’t face any significant restrictions and that are looking to keep startup capital costs low. Recently, a major engineering firm in Kansas developed a feasibility study for an upcoming greenfield project. Due to the large open area available for the woodyard, the new system did not require enclosures or dust control. Without these limitations, it was possible to design a manual system well within the client’s modest startup budget.
Semi-Automated Fuel Feed Systems
For many, a balance between the extremes of automated and manual fuel feed systems is often the best approach to woodyard design. A semi-automated system typically introduces automation into either the stackout or reclaim end of the fuel-feed chain to keep startup capital costs in check while reducing operational expenditures.
A good example of this approach is the Fort Drum biomass conversion project, which used an automated stackout system to connect its fuel delivery location with a separate woodyard so that the system could fit within the site’s limited footprint and still keep up with the 60-MW plant’s aggressive fuel-feed needs. (For more details about this project, please see our case study.)
Custom Woodyards Work Best
Whether you’re talking about an automated, manual, or semi-automated design, it takes thorough on-site inspection, careful analysis, and hard-won experience to develop a woodyard to suit a particular facility. The fact is, woodyards are complex engineering challenges that need to be custom designed to meet varied criteria. Sure, you can go with a standardized system, but when production and performance are an issue, a pre-designed system isn’t going to work and may end up costing you more in the long run.
If you’re considering implementing a new woodyard or simply want help optimizing your existing one, please call us at 1-888-663-2028 to talk shop. We’ll be happy to offer advice and work with you to develop a plan that meets your site’s particular needs.