Best Practices for Biomass Feedstock Handling and Management Wood Waste to Energy Facility for Tomslake/Kelly Lake

Transcription

1 Best Practices for Biomass Feedstock Handling and Management Wood Waste to Energy Facility for Tomslake/Kelly Lake Prepared for: Kelly Lake Metis Settlement Society & Waste to Energy Canada July 23, 2012 Reed Environmental 548 Cornwall Street Victoria BC, V8V 4L1

2 Table of Contents 1.0 Introduction Background Project Objectives Best Practices Best Practices for Contracted Services Best Practices for Plant Operations Summary of Best Practices Report Prepared By: Nygil Goggins, MRM Senior Project Manager July 22, 2012 Report Reviewed By: Jesse Ketler, MSc Senior Environmental Consultant July 23, 2012 Reed Environmental Inc. 2

3 1.0 Introduction Reed Environmental was commissioned by the Kelly Lake Metis Settlement Society (KLMSS) and Waste to Energy Canada (WTEC), the Project Proponents hereafter, to complete a literature review of best practices for the handling and management of biomass feedstock. The feedstock will be utilized by a Continuous Gasification System (CGS) plant proposed for the Tomslake/Kelly Lake region. The objective of this study is to inform critical supply chain decisions in terms of contracting, equipment, infrastructure and logistics. This review considers best practices for the handling and management of biomass feedstock at each step in the supply chain: Harvesting and Collection Comminution (Chipping/Shredding) and Loading Transportation and Unloading Storage and Conveyance Facility Layout and Design The following project objectives were considered when defining best practices: Minimize delivered cost of biomass energy and avoid price volatility Minimize the risk of unscheduled down time Align feedstock characteristics with plant specifications Ensure health and safety of employees Identify and mitigate environmental impacts Identify and mitigate social impacts The approach taken in this report is to define best practices at each step in the supply chain based on project objectives. The Project Proponents were consulted on project objectives and key concerns, and a literature review was completed to determine best practices for achieving those outcomes. This study draws on the results of previous work completed for this project: Kelly Lake Woody Debris Characterization Study Discovery trips and practice assessments conducted by WTEC Kelly Lake Continuous Gasification System Emissions Management Specifications The results from this study will be used to inform the Front End Engineering Design (FEED) study and the final Biomass Feedstock Logistics Plan. This report concludes with a summary of best practices based on the preliminary concept plan for the plant and operations. Reed Environmental Inc. 3

4 2.0 Background Feedstock Availability The Woody Debris Characterization Study identified four types of available biomass feedstock in the region (roadside waste, sawdust, bark, standing timber), each with varying physical characteristics at a relatively uniform average delivered cost. A recommendation of the report was to get firm quotes on biomass feedstock supply and to initially target standing pulp-grade timber through BC Timber Sales and private land. The Biomass Feedstock Logistics Plan will be tailored to the secured feedstock supply. The Project Proponents are planning to use a private contractor to deliver processed feedstock to the plants gates. The same contractor may also be responsible for managing onsite feedstock. This report assumes that the contractor will be responsible for delivering feedstock to the plant and plant operations will be responsible for onsite feedstock management. Table 1: Available biomass feedstock within 150km of the site (green tonnes) (tonnes) Softwood Hardwood Total Biomass Cost/GTonne Cost/ODT* Roadside Waste 152, , , Sawdust 162, , Bark 50,781-50, Private Land 20, , , BC Timber Sales 652, , , Total 1,038, ,773 1,611,814 Source: Kelly Lake Woody Debris Characterization Study CGS Plant Feedstock Specifications WTEC s CGS plant can operate with a heterogeneous feedstock in terms of bulk density, moisture content, and energy density. However, the performance of a CGS plant can be enhanced by optimizing plant specifications to a relatively homogeneous feedstock with narrow set of parameters. The following parameters were provided as optimal ranges for the characteristics of biomass feedstock supplied to the plant: Bulk Density: Less than or equal to 4 inches in diameter Moisture content: Average batch of less than 35% Energy Density: Greater than 10 GJ/tonne [determined by moisture content] Regional Weather Regional weather is a determinant of best practices for the handling and management of biomass feedstock. As identified in the Woody Debris Characterization Study, moisture content decreases energy density and increases transportation costs. Other considerations include supply risk due to flooding in the spring, fires in the summers and snow conditions in the winter. Reed Environmental Inc. 4

5 The region experiences long cold winters with relatively low daily average temperatures in the summer. Annual precipitation in the region is below average and maximum average snow depths reach 31cm for two months of the year. However, extreme single day snow events of 30cm have been recorded as well as extreme daily snow depths of up to 80cm. Table 2: Weather statistics for Dawson Creek area (Weather Network) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Temperature (C) Monthly Rainfall (mm) Monthly Snowfall (cm) Average Snow Depth (cm) Project Objectives The following are project objectives identified by the Project Proponents. Best practices will be used to inform decisions aimed at achieving these objectives. Feedstock Cost The cost per unit of useful energy delivered to the CGS plant is one of the most significant determinants of the projects financial viability. Optimization will be required throughout the entire biomass feedstock supply chain to minimize the cost per unit energy delivered to the plant. The primary objective is to reduce the cost of biomass feedstock while minimizing price volatility. Supply Risks and Downtime Disruptions in biomass feedstock supply or unscheduled downtime due to equipment failure represents lost revenue for a bio-energy plant. With the exception of downtime for plant maintenance, the objective is to maintain the plant at 100% capacity by mitigating risk factors for biomass supply and equipment failure. The remote location of the plant raises concerns of increased downtime due to equipment failure if the appropriate parts/trades/technicians are not available. Additional concerns of biomass supply risks can be attributed to extreme snow and rain events that can lead to road closures, forest fires, equipment failure, and labour and contractor shortages. Feedstock Characteristics As described above, WTEC s CGS system specifications can be optimized around a consistent set of biomass characteristics. Specifically, the objective will be to deliver biomass feedstock at a relatively consistent size of less than four inches in diameter with an average moisture content of less than 35% per batch. Moisture content is a critical characteristic that affects costs from the time the material is harvested until it is converted into useful energy. Given that increasing Reed Environmental Inc. 5

6 feedstock uniformity increases cost, the objective of feedstock quality will need to be optimized against the objective of reducing bio-energy feedstock costs. Health and Safety The health and safety of workers and contractors is a priority concern for the Project Proponents given the reliance on heavy machinery and industrial processes in a remote location. The objective will be to exceed health and safety standards to ensure that risks of injury and harm are minimized. Environmental Impacts The biomass to energy plant will have a net benefit to the environment by offsetting the need for fossil fuel based electricity and the development of new large hydro projects. The Kelly Lake Continuous Gasification System Emissions Management Specifications report indicates that the best available control technologies will be used to reduce plant emissions. The Project Proponents aim to further reduce environmental impacts that could occur at each step in the supply chain, including: minimizing the impacts of harvesting and collection on the forest floor, reducing fossil fuel use through efficiency gains and fuel switching, avoiding the release of hazardous materials; and minimizing air pollution. 4.0 Best Practices Best practices for the handling and management biomass feedstock are dependent on project objectives. As such, the approach utilized in this study was to first identify the project objectives, and second to consider the best approaches to meeting those objectives at each stage of the supply chain. In defining best practices for the supply of biomass feedstock it is important to differentiate services that will be provided by independent contractors from regular plant operations. For services provided by independent contractors, best practices will focus on ensuring that contracts are performance based creating incentives that are aligned with project objectives. 4.1 Best Practices for Contracted Services Harvesting, Collection, Site Processing, Loading, Transportation and Unloading Supply contracts for the delivery of biomass should base payment on the energy delivered or the oven dry tonne (ODT) delivered to account for moisture content. This form of contract will Reed Environmental Inc. 6

7 ensure that contractors have an incentive to deliver dry wood which has a much higher energy density. The Kelly Lake Woody Debris Characterization Study indicated that competition for feedstock supply may be low in the region. With limited competition, best practice is to work with contractors to ensure that efforts are being made to streamline processes and increase efficiency. Equipment efficiency is a key concern for harvesting and collection. Best practice is to ensure that equipment capacity is not oversized and processes are efficient. This is particularly true for roadside waste as the machinery utilized is generally designed for harvesting large stems. Steps should be taken to ensure that the contractor is managing supply risk. This could be achieved by including a penalty for supply disruption or by working with contractors to develop supply risk mitigation plans. Best practice for managing supply risk from roadside waste and standing timber is long term planning and diversified supply. For example, supply from a single woodlot could be disrupted by fire, flooding, road outages or contract issues. Feedstock supply and risk mitigation plans should be developed and renewed regularly for the short and long term. Contract terms should require private contractors to demonstrate that supply risk is being considered and managed. The cost premium of diversifying supply should be weighed against the alternative of stockpiling biomass feedstock on site to manage supply risk. Contract terms should also specify that the contractor is responsible for exceeding environmental standards and standards for health and safety. 4.2 Best Practices for Plant Operations Facility Design and Building Layout The proposed site has a total footprint of 4000m 2 and the proposed building footprint is 3000m 3 (see Figures 1-3 below). Table 3 illustrates the approximate area required for a 4000 tonne pile of woodchips which could supply the plant for 10 days. The plant will need approximately 10 B- Trains of chips delivered per day to operate at full 400 tonne/day capacity. Table 3: Chip pile dimensions and weight (assumes bulk density of 0.4m 3 /tonne) Pile Height (m) Pile Width (m) Floor Area (m 2 )* m 3 per Pile Tonnes/Pile *assumes a square area with 2m of passage on each side WTEC plants currently apply best practices for plant layout and design (see Figures 1-3). Biomass feedstock is unloaded at the building gates and piled under a covered area to facilitate drying. Material is then loaded into a hopper that feeds conveyors for loading the gasification chambers. Best practice would be to design a system that utilized waste heat to pre-dry the biomass prior to gasification to increase calorific value. Best practice for biomass plants is to control plant emission with a cyclone to reduce dust. Best practices should be reviewed for updates in light of the two lumber mill explosions experienced this spring in BC. Reed Environmental Inc. 7

8 Figure 1: Facility layout Figure 2: Equipment layout Figure 3: Example of gasification trains and conveyors Reed Environmental Inc. 8

9 Onsite Comminution (Chipping/Grinding) Best practices for comminution of biomass is dependent on the requirements for size consistency and the amount of rock contaminants expected in the biomass feedstock. Onsite comminution will be limited to stems delivered from private land and BC Timber Sales which should be low in contaminants. Best practice is to process roadside waste (slash) in the field to reduce to transportation costs. A case study on the performance of various chipper and grinder technologies concluded that equipment output is relatively similar, with logistics of loading and unloading generally being the limiting factor for output 1. In general, the price of comminution technology increases with the consistency of the processed feedstock. An important consideration for this project will be regional familiarity with the technology selected. Electric drive chippers/grinders can be used on site to increase efficiency and reduce fossil fuel use. Reports indicate that similar capacity stationary chippers/grinders can usually be installed for about half of the cost per chipped tonne in contrast to portable equipment 2. Storage of Chips and Stems Storing wood chips in tall loose piles in uncovered areas can reduce moisture content to acceptable levels without unacceptable chip degradation 3. The loss of calorific value via decomposition has been estimated at 1% per month 4. Best practice is to avoid storing comminuted material for more than two weeks to minimize calorific loss, spore growth and the risk of spontaneous combustion. Whole stems can be stored for up to a year without significant calorific loss. As such, whole stems versus wood chips should be stock piled to manage long term supply risks. Stems should be stacked in a well drained area to encourage drying. Chip sizes should be uniform and as large as possible to maximize air flow. Providing coverage with tarps on the very top of the pile will help reduce the moisture content while maintaining air circulation. Sawdust should not be mixed with chips as this will reduce circulation. Uncovered piles stored outside should be as tall as possible, without exceeding the 15m limit, to increase the core to surface ratio. Consideration should be given to options for using waste heat to dry wood chips prior to entering the facility. Risks associated with wood chip storage include spontaneous combustion and exposure to wood dust and fungal spores. Spontaneous combustion can be avoided by reducing pile sizes in the summer and rotating piles regularly to reduce microbial activity. Fungal spores are a significant health hazard associated with wet chips. Chip storage should be monitored and scheduled to optimize moisture content and reduce the risk of spontaneous combustions and health impacts associated with fungal spores. Trial studies have concluded that placing tarps on chip pile tops STORAGE%20FILE14947.PDF 4 Reed Environmental Inc. 9

10 can reduce moisture content by 10%, which increase the net calorific value by roughly 10% providing a significant payback. Feedstock Conveyance Best practice is to utilize conveyors where feasible instead of loaders to increase efficiency, reduce fossil fuel use, and reduce the risk of injury from heavy equipment operation. Belt conveyors are better suited at moving mixed sizes of feedstock than screw conveyors. The design of the conveyor system will be completed with the FEED study. Emergency Procedures and Risk Management Effective risk management is the identification, assessment, and prioritization of risks, followed efforts to minimize, monitor, and control the likelihood of occurrence. Best practice is to develop a systematic approach to managing risk and seek certification such as ISO Common practice is to develop risk management checklists to be used by operations staff Summary of Best Practices The following is a preliminary summary of best practices for the handling and management of biomass feedstock based on the initial project concept and design. Contracts 1. Contracts are performance based and designed to increase incentives for efficiency and innovation. 2. Contracts for biomass delivery are based on energy content (GJ/Tonne) or dry basis (ODT). 3. Contracts include a requirement for supply management plans from contractors to ensure that supply risks are being managed. 4. Contracts include additional incentives for efficiencies and incentives in areas with low competition. Facility Layout 5. Cement slabs used for sorting and storing wood chips to reduce moisture content and contaminants. 6. Use of waste heat to pre-dry chips. 7. Well drained area, such as crushed rock, for the outdoor storage of stems. Onsite Comminution 8. Utilize electric dive equipment to increase efficiency, reliability and reduce greenhouse gases fcece4e9fcadbfd c548cc Reed Environmental Inc. 10

11 Storage 9. Develop inventory management and tracking system to optimize feedstock characteristics and manage supply risks. 10. Minimizing pile heights to less than 15M in height and monitor pile temperatures. 11. Location selection to maximize natural drying. 12. Avoiding stockpiling of comminuted residues for more than two weeks to minimize spore growth and calorific loss. 13. Utilize stems for storage to reduce long term supply risk. 14. Tarp the tops of outdoor piles to reduce moisture content. Feedstock Conveyance 15. Assess the payback on conveyors over the project lifecycle and account for nonfinancial factors such as health and safety of employees. 16. Utilize electric drive belt conveyors. Emergency Procedures and Risk Management 17. Adopt a risk management process and seek certification such as ISO Ensure that risk management procedures are followed by operations staff and contractors. 19. Reduce the risk of delays associated with equipment failure by sourcing equipment with readily available parts that can be repaired with local expertise. Reed Environmental Inc. 11