As an established bioenergy industry, the global wood pellet sector is ideally positioned to adopt biomass torrefaction technologies. In this review, potential benefits and challenges of integrating torrefaction within the pellet industry are reviewed and the required technological interventions to enable this integration are analyzed. It is apparent that integration would accelerate the commercialization of biomass torrefaction and benefit the wood pellet industry, torrefaction developers, as well as coal-based utilities. Torrefied pellets are expected to have distinct applications in power generation and help coal-based utilities to reduce their emission levels and comply with increasingly stringent regulations. Co-firing coal with black pellets requires little-to-no retrofit of the existing power plant and, therefore, can offer a low-cost solution. Two potential pathways, in either an upstream or downstream configuration, for retrofitting torrefaction within a white pellet facility are assessed. A successful upstream integration can potentially produce highly dense and durable torrefied pellets. However, the current limitations with this approach are (a) greater reactor volume required for torrefying wood chips and consequently high capital expenses (CAPEX); (b) difficulty in densification; (c) frequent maintenance requirements due to the abrasive nature of torrefied biomass; and (d) safety concerns from fine generation. Torrefaction as a downstream operation, wherein white pellets are subsequently torrefied to produce black pellets, has the benefit of being a simple bolt-on integration. Downstream integration eliminates the need for additional grinding and pelletizing capacity, while minimizing plant-wide contamination due to dust generated from the processing of torrefied biomass. Furthermore, CAPEX can be reduced, as a typical torrefier has significantly higher throughput when processing pellets compared to wood chips. The limitation of downstream integration includes the potential compromise in pellet quality, especially a loss in strength and density. While the benefits of integrating torrefaction are numerous, the techno-economics for each pathway should be further examined.

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The expanded use of environmentally friendly and sustainable foodservice packaging continues to be a prime focus of stakeholders across the foodservice value chain. Paper-based coffee cups is one product segment where effective recycling of waste cups remains elusive. As a result, material substitutes for polyethylene liners are emerging to solve the problem of waste cups. In this paper, current and emerging commercial material technologies used in the production of paper-based coffee cups that are readily recyclable with other paper grades are reviewed. Many of these material solutions are also compostable. Special attention is paid to the rapidly evolving, alternative large-scale production of bioplastics. Multiple efforts to effectively develop a more environmentally friendly paper cup are also examined. It is clear that broad adoption of proposed solutions will require an integrated commitment and approach to circular economics. Specifically, this includes: changes in consumer behavior; brand owner initiatives to meet sustainability goals; governmental policies that limit or forbid use of fossil-based cups; and easily accessible infrastructures at the consumer level for the collection, separation, and processing of biodegradable cups.

This review article highlights progress in understanding the optical properties of paper. Paper’s appearance can be defined in terms of its opacity, brightness, color, fluorescent properties, gloss, and various quantities related to its uniformity. The phenomena that give rise to paper’s optical properties, especially its ability to scatter and absorb visible light, are highly dependent on paper’s structure and its chemical composition. In an effort to engineer low-cost products having relative high opacity and brightness, it is necessary to optimize the material selection and processing conditions. The dimensions of solid materials and void structures within the paper are key factors for optimizing the optical properties. In addition, additives including bleaching agents, mineral particles, dyes, and fluorescent whitening agents can impact paper’s optical properties Paper’s appearance depends, in subtle ways, on the processes of its manufacture.

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