LAUSR

The first four papers of this August issue form a special section, which presents recent work in the area of sustainable bioenergy systems design, planning and operations. An open call for papers on this special topic was announced in October 2018. After multiple rounds of review, four articles were accepted to this special section, following the standard, rigorous review procedures of IISE Transactions. The studies presented in this special section focus on the use of biomass for generation of renewable fuel, renewable electricity, and consumable products, such as paper and sugar. These studies are motivated by the potential to use biomass to meet our needs for energy and other bio-based products. The growing interest in this research is a reflection of increased awareness about the impacts that our decisions and lifestyles have on the environment. Bioenergy and biobased products are environmentally friendly, thus, sustainable. Additionally, the development of a bio-based economy enables farmers to find new markets for their products, creates new jobs in rural areas, and enhances value for farmers and national economies. The selected group of papers published in this special section addresses a wide range of problems that are motivated by existing challenges and recent developments faced by this industry. In the last two decades, most of the literature has focused on optimizing the design and management of biomass supply chains, due to the logistical challenges faced in biomass collection, storage and transportation. Biomass – in the form of agricultural products and agricultural waste, forest products and forest waste, animal waste, and municipal waste – is widely spread geographically. Biomass loses dry matter with time, it is bulky, its production yield is uncertain and difficult to predict. As a result, its collection, storage, and transportation are expensive. The work by Nur et al. extends this research by considering the impact that product characteristics, such as moisture content and ash content, have on the supply chain costs. For example, a bale with high moisture content is heavier, thus more expensive to transport. Certain conversion processes, such as biochemical conversion, use biomass with low ash content. This requirement restricts supplier selection process and increases transportation costs. Nevertheless, well-designed plans help biofuel producers to reduce the impact of moisture and ash on supply chain costs. For example, scheduling the delivery of biomass before the rain season reduces moisture content. The work by Nur et al. assumes a hub-and-spoke supply chain structure, which considers that biomass is pre-processed at a depot located near farms. The processed biomass has higher density; thus, it is easier to transport. Such a supply chain structure facilitates the use of high-volume transportation modes. These strategies lead to lower supply chain costs. Biomass supply and price uncertainty is another challenge faced by bioenergy producers. Biomass supply is affected by weather conditions, insect population, and plant diseases. Additionally, changes of land use from one year to the next impact biomass supply and price. Shortages of biomass supply have a negative impact on utilization of resources and production amounts, and thus on revenues and profits. Developing long-term contractual agreements among biomass providers and biofuel producers mitigates price and supply volatility. Establishment of long-term contracts also incentivizes farmers to produce energy crops such as switchgrass. The work by Memişo glu and € Uster presents a strategic framework that is needed to assist biofuel producers in designing their bioenergy supply chain networks while simultaneously determining the policies that give incentives to farmers to stimulate biomass supply. The model’s objective is to maximize the expected profit, which is the main objective for biofuel producers who consider investing in the bioenergy industry. The opportunity to use biomass to meet our needs for energy and to reduce greenhouse gas emissions (from burning of fossil fuels), were main motivations for the U.S. Environmental Protection Agency and the U.S. Department of Energy to develop policies, such as the renewable fuel standards and Production Tax Credit (PTC), which stimulate production of bioenergy and its consumption for commercial and personal use. The work by Khademi and Ekşio glu focuses on PTC, a federal incentive that provides financial support to power plants that cofire biomass. This is a flat rate per megawatt-hour of renewable electricity generated and is provided for the first 10 years of a plant’s operations. Khademi and Ekşio glu show that the current structure of the PTC (flat rate) prioritizes large-scale plants, as they can displace more coal with biomass and take advantage of the economies of scale. The ethics of this disproportionate allocation of taxpayers’ money motivated their work, which identifies two designs of the PTC that focus on fair allocation of resources. The proposed flexible tax credit provides a plant-specific tax credit rate based on plant capacity, with small-size plants receiving a higher tax credit than large-size plants. Such an approach leads to increased renewable electricity generated since it motivates smaller plants to participate. The work by Zhu et al. expands the scope of these biomass supply chain models by investigating opportunities to exploit unutilized resources or by-products, and thereby increase recourse utilization in the supply chain and