No abstract

Background: The goal of the study is to examine the general public's understanding and perceptions of bioenergy and biofuels in North Carolina (NC) and Tennessee (TN). The study focuses on the public concerns, support and risk evaluations of alternative bioenergy feedstocks and biofuels, and includes an assessment of the economic, environmental, social, and policy impacts of bioenergy production and use. Methods: A sample of consumers in NC and TN were surveyed in the fall of 2013 and spring of 2014 for their perceptions about bioenergy and specifically, biofuels for transportation. Five hundred eighty-six consumers completed the questionnaire electronically (376 in NC and 210 in TN). Results: Respondents reported that the price and vehicle compatibility with biomass-based transportation fuels were the most important factors in their choice of biofuels over gasoline at a pump. Results show that the acceptance of bioenergy depends on the extent of knowledge and available information to consumers about the energy source. A principal component analysis (PCA) indicated seven distinct dimensions of consumer's perception about bioenergy. The key dimensions are the following: how bioenergy benefits the society, risks of bioenergy use, government support for bioenergy, increase in food cost, conditional use of trees, support for low-cost biofuel alternative to current energy, and market attributes of bioenergy purchase. Conclusions: The findings from this study reflect the need for communicating the benefits and risks from the use of bioenergy to the general public through trustworthy channels of communication and targeted policy, market, and institutional support.

This literature review aims to provide a systematic analysis of studies on the financial aspects of producing torrefied biomass and torrefied pellets. There are substantial differences in the specific technologies, operating conditions, scale of the demonstration, and properties of biomass feedstock. There is a lack of reports that consider the entire supply chain, which is required for an understanding of the high-cost steps. To obtain a robust view of the torrefaction processes' financial prospects the authors have used both peer-reviewed and non-peer-reviewed papers that allowed the researchers to include thirty-one papers in this analysis. All these studies establish that the prices of the biomass and the final torrefied product are critical. The product yield and caloric content, which are related to pricing, were also key financial drivers. The lower freight costs due to high-energy density of the torrefied pellets was recognized and calculated, but some other benefits were not quantified. There is a need for a detailed and flexible torrefaction financial model that includes variations in financial assumptions and biomass properties. Given the uncertainty around many specific steps, there is value in including stochastic tools in these financial analyses.

Linear programming was used to optimize the economic, environmental, and social impacts of forest biomass used for bioenergy production. Sixteen scenarios (combinations of feedstocks, products, markets, and end use) were studied. Two feedstocks (roundwood and wood residues), two densifi ed bioenergy products (white pellet, torrefi ed pellet), two markets (domestic, international), and two end uses (power generation, district heating) were evaluated. The social, environmental, and economic sustainability attributes were quantifi ed and monetized using peer-reviewed literature to analyze the trade-offs. Using the economic criteria alone, the model showed that the best solution was use of 70% roundwood and 30% forest residue feedstock to produce torrefi ed pellets (TP) sold for district heating in the EU. The model predicts $5.4 million annual profi t which is driven by the use of lower cost forest residue feedstocks, and relatively higher prices for the heating market in the EU. Inclusion of all three sustainability attributes led to a different optimized solution. TP produced from roundwood and sold to the EU market for heating was the optimum, due to the social benefi ts derived from increased local income to landowners and reduced shipping costs. It also had added benefi ts of reductions in emissions across the transportation system on an energy basis. TP consistently had higher social benefi ts than WP due to the need for more biomass per unit of fi nal product, and providing more local jobs and income from feedstock production. The increasing costs of carbon emissions increased the environmental benefi ts of TP compared to WP or coal.