Data available for evaluating the risks and benefits of MTBE and ethanol as alternative fuel oxygenates

Public attitudes toward biofuels. Effects of knowledge, political partisanship, and media use

Despite large-scale investments and government mandates to expand biofuels development and infrastructure in the United States, little is known about how the public conceives of this alternative fuel technology. This study examines public opinion of biofuels by focusing on citizen knowledge and the motivated processing of media information. Specifically, we explore the direct effects of biofuels knowledge and the moderating effect of partisanship on the relationship between media use and benefit vs. risk perceptions in the following four domains: environmental impacts, economic consequences, ethical/social implications, and political ramifications. Our results suggest that more knowledgeable respondents see fewer benefits of biofuels relative to risks, and that Democrats and Republicans are affected differently by media use when forming opinions about biofuels. Among Democrats, greater attention to political media content leads to a more favorable outlook toward the technology across several domains of interest, while among Republicans, an increase in attention to political content has the opposite effect. Possible reasons for these results, as well as implications of the findings at the intersection of politics and the life sciences, are discussed.

Biodegradation of alkylates under less agitated aquifer conditions

The biodegradability of three alkylates (2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane) under less agitated aquifer conditions was investigated in this study. All three alkylates biodegraded completely under these conditions regardless of the presence or absence of ethanol or benzene, toluene, ethylbenzene, and xylenes (BTEX) in the feed. In the presence of ethanol, alkylates degradation was not inhibited by ethanol. However, alkylates degraded more slowly in the presence of BTEX suggesting competitive inhibition to microbial utilization of alkylates. In the sterile controls, alkylates concentrations remained unchanged throughout the experiments.

Modeling the influence of ethanol on the adsorption and desorption of selected BTEX compounds on bentonite and kaolin

The influence of ethanol on the adsorption capacity and desorption kinetics of benzene and toluene on bentonite and kaolin through modeling and experimental study was investigated. The results showed that the adsorption capacity of both soils for the target compounds decreased as ethanol content increased. As ethanol content increased from 0 to 50%, the adsorption capacity for benzene and toluene on bentonite decreased from 3.6 to 0.54 microg(n+1)/(L(n) x g) (by 85%) and 1.91 to 0.01 microg(n+1)/(L(n) x g) (by 99.5%), respectively. For benzene and toluene adsorption on kaolin, the adsorption capacity decreased by 86.5% (from 0.26 to 0.04 microg(n+1)/(L(n) x g) and 98.2% (from 0.13 to 0.002 microg(n+1)/(L(n) x g)), respectively, as ethanol content increased from 0 to 50%. In addition, the desorption rate of benzene and toluene from bentonite decreased by about one order of magnitude as the ethanol increased from 0 to 25% and 0 to 50%, respectively. It can be inferred that ethanol could affect the effectiveness of natural attenuation processes that rely on adsorption to soils as a containment technique for benzene and toluene by retarding the adsorption to soils and remobilizing compounds that had already been adsorbed to soils.

Next-generation biofuels: Survey of emerging technologies and sustainability issues

Next-generation biofuels, such as cellulosic bioethanol, biomethane from waste, synthetic biofuels obtained via gasification of biomass, biohydrogen, and others, are currently at the center of the attention of technologists and policy makers in search of the more sustainable biofuel of tomorrow. To set realistic targets for future biofuel options, it is important to assess their sustainability according to technical, economical, and environmental measures. With this aim, the review presents a comprehensive overview of the chemistry basis and of the technology related aspects of next generation biofuel production, as well as it addresses related economic issues and environmental implications. Opportunities and limits are discussed in terms of technical applicability of existing and emerging technology options to bio-waste feedstock, and further development forecasts are made based on the existing social-economic and market situation, feedstock potentials, and other global aspects. As the latter ones are concerned, the emphasis is placed on the opportunities and challenges of developing countries in adoption of this new industry.

Biodegradability of alkylates as a sole carbon source in the presence of ethanol or BTEX

The biodegradability of alkylate compounds in serum bottles was investigated in the presence and absence of ethanol or benzene, toluene, ethylbenzene, and p-xylene (BTEX). The biomass was acclimated to three different alkylates, 2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane in porous pot reactors. The alkylates were completely mineralized in all three sets of experiments. They degraded more slowly in the presence of BTEX than in their absence because BTEX inhibited the microbial utilization of alkylates. However, in the presence of ethanol, their slower biodegradation was not related to inhibition by the ethanol. Throughout the experiments alkylates, ethanol, and BTEX concentrations did not change in the sterile controls.

Systematic Approach to Evaluating Trade-Offs among Fuel Options: The Lessons of MTBE

The fuel additive methyl tertiary butyl ether (MTBE) has been used in an effort to improve air quality in the United States, but other undesirable effects, particularly the contamination of water resources, were eventually judged to outweigh any air quality benefits it may have offered. The experience with MTBE offers many lessons, including the need to evaluate potential positive and negative environmental impacts associated with fuel choices using a comprehensive approach that combines a product life-cycle perspective with the risk assessment paradigm. Such an approach, referred to as "comprehensive environmental assessment" (CEA), is illustrated here by highlighting some of the issues that might be considered in evaluating reformulated gasoline (RFG) produced with MTBE, ethanol, or no oxygenate.