Characterization of woodstove briquettes from torrefied biomass and coal

peer-reviewedUsing waste biomass materials offers the potential to reduce the greenhouse gas emissions from fossil fuels. Torrefaction is very useful for improving the fuel properties of biomass in order to better match those of coal. The aim of this work is to compare the properties of torrefied low quality biomass briquettes against coal equivalents. The composition of the briquettes was characterized by 13C CP/MAS, proximate analysis, and X-ray diffraction and the results were compared with equilibrium calculations. In addition to these techniques, we report for the first time on the use of XμCT for characterizing such materials. The XμCT analysis showed that the briquette structure contains carbon, binder and inorganic matter, with quartz retained from the original feedstock in torrefied biomass and coal briquettes. The CO2 reactivity of pulverized briquettes was investigated by thermogravimetric analysis. Results showed that the inorganic matter influences the reactivity less than the organic composition and porosity. Importantly from a technological standpoint, the increase in binder concentration and replacement of starch with resin binder did not influence the reactivity and calorific value of a pulverized briquette

Methods to Elicit Forecasts from Groups: Delphi and Prediction Markets Compared

Traditional groups meetings are an inefficient and ineffective method for making forecasts and decisions. We compare two structured alternatives to traditional meetings: the Delphi technique and prediction markets. Delphi is relatively simple and cheap to implement and has been adopted for diverse applications in business and government since its origins in the 1950s. It can be used for nearly any forecasting, estimation, or decision making problem not barred by complexity or ignorance. While prediction markets were used more than a century ago, their popularity waned until more recent times. Prediction markets can be run continuously, and they motivate participation and participants to reveal their true beliefs. On the other hand, they need many participants and clear outcomes in order to determine pay-offs. Moreover, translating knowledge into a price is not intuitive to everyone and constructing contracts that will provide a useful forecast may not be possible for some problems. It is difficult to maintain confidentiality with markets and they are vulnerable to manipulation. Delphi is designed to reveal panelists’ knowledge and opinions via their forecasts and the reasoning they provide. This format allows testing of knowledge and learning by panelists as they refine their forecasts but may also lead to conformity due to group pressure. The reasoning provided as an output of the Delphi process is likely to be reassuring to forecast users who are uncomfortable with the “black box” nature of prediction markets. We consider that, half a century after its original development, Delphi is under-utilized

Viscosity Model for Oxide Melts Relevant to Fuel Slags. Part 2:The System SiO2_{2}-Al2_{2}O3_{3}-CaO-MgO-Na2_{2}O-K2_{2}O"

The viscosity model recently developed for fully liquid pure oxides and binary systems is extended to describe the viscosity of multicomponent systems, based on the thermodynamic modified associate species model. In the model the viscosity is linked to the distribution of associate species as well as the connectivity of associate species. To describe the viscosity for multicomponent systems, the ternary associate species are introduced. The focus of the present paper is to describe the viscosity of the system SiO2–Al2O3–CaO–MgO–Na2O–K2O and its ternary or higher order subsystems. The model shows a good performance in describing the viscosity using only one set of model parameters, which all have a clear physico-chemical meaning. The viscosity behavior when substituting one network modifier for another at constant SiO2 contents is well described. The Al2O3-induced viscosity maximum is also well described, in which the position and magnitude of the viscosity maximum as a function of composition and temperature (charge compensation effect) are properly predicted. Another viscosity maximum when replacing Al2O3 with SiO2 for constant contents of the network modifiers is well presented. Moreover, the current model is self-consistent, in which the extension of viscosities from lower order systems to higher order systems works well, and vice versa