Comparing pelletization and torrefaction depots: Optimization of depot capacity and biomass moisture to determine the minimum production cost

Abstract

In the present study, the biomass upgrading depot capacity and biomass feedstock moisture were optimized to obtain the minimum production cost at the depot gate for the production of woody biofuels. Three technology scenarios are considered in this study: 1) conventional pellets (CP), 2) modestly torrefied pellets (TP1) and severely torrefied pellets (TP2). TP1 has the lowest cost of $7.03 /GJ LHV at a moisture of 33 wt.% and a depot size of 84 MW LHV. The effects of climatic conditions and biomass field conditions were also studied for three scenarios. In humid regions of Michigan, TP2 is more economical than other scenarios because of the increased production of combustible gas. The three scenarios have similar sensitivities to biomass field conditions.

GIS method to design and assess the transportation performance of a decentralized biorefinery supply system and comparison with a centralized system: case study in southern Quebec, Canada

“…The sizing of the depots is based on a resource approach that determines the available supply of corn stover in the territory. The assumptions of depots’ size in this study are smaller than those in the literature because of the pedoclimatic conditions, the dispersion of the feedstock in the territory, and the low participation rate of farmers. To select the sizing of the biomass depots, Eqn (3) is used (adapted from Ministry of Natural Resources of Quebec) to estimate the potential tonnage of corn stover technically and ecologically available in southern Quebec: where CS a is the potential corn stover technically and ecologically available annually in the research area (DMg); A is the potential harvested corn lands area, set to ~200 k ha (120 km radius); LR is the ratio of corn lands in Quebec that can tolerate material removal, set to 50% authors’ assumption based on literature; Y is the grain yield, average 2015–2017, set to 10.2 Mg ha −1 (163 bu ac −1 ) (15% moisture content); WR is the residue‐to‐grain weight ratio, set to 66% authors’ assumption based on the land yield and the culture condition; RR is the stover removal ratio, set to 25% based on the soil quality and yield; and AR is the annual biomass availability rates (farmers’ participation rate), set to 10–40% authors’ assumption based on literature…”

“…In this industry, there is no clear rule of economies of scale. A larger biorefinery implies a larger supply radius, which increases the transport cost of a low‐density biomass …”

Optimization methods applied to renewable and sustainable energy: A review

“…They analyzed the effects under three conditions 1) Balanced market, under oligopolistic-oligopsonistic equilibrium pricing 2) Bio-refineries maintain a supply region, based on average yield density 3) Bio-refineries maintain a supply region, based on "Derisked" yield density. Chai and Saffron (2016) considered 3 scenarios with regard to storage capacity and the amount of biomass moisture content in order to produce woody biomass-based biofuel. Their model minimizes the costs and determines the amount of moisture and biomass optimal warehouse size.…”

Subregional Comparison for Forest- to-Product Biomass Supply Chains on the Pacific West Coast, USA

“…Lamers et al (2015) suggested the benefits from incorporating biomass processing facilities (biomass depots) into the overall feedstock supply chain outweigh the costs and should be aggressively pursued. Chai and Saffron (2016) reviewed optimal capacity for pellet and torrefied wood depot facilities highlighting the dependence of moisture (drying energy) with optimal depot ranges between 60-100 MW [450,000-815,000 bdmt yr -1 (500,000-900,000 bdt yr -1 ) of feedstock] while others have suggested 63,000-135,000 bdmt yr -1 (70,000-150,000 bdt yr -1 ) may be optimal for fixed placement pellet depots (Sultana et al, 2010).…”

“…Studies have typically not looked at a wide range of regional variations in supply chain costs of mobile systems, though portions of the biomass supply chain have been studied including trucking capacities and supply implications Jacobson et al, 2016). The study of transportable facility design to produce higher value wood products (biochar, torrefied wood, briquettes, pellets) is less studied (Chai and Saffron, 2016;Berry and Sessions, 2018a, b). Berry and Sessions (2018a) take this concept a step further by optimizing strictly transportable facilities [13,,000 bdmt yr -1 (15,000-50,000 bdt yr -1 )] for a biochar facility finding optimal time between moves being 1 to 2.5 years.…”