Life cycle sustainability assessment of higher alcohol: energy, environmental, and social indicators

One of the most current discussions in the transportation sector is air pollution caused by diesel engines. In fact, even with the advances in engine technologies, the combustion of diesel in internal combustion engines leads to the significant release of toxic gases into the atmosphere, such as particulate matter and nitrogen oxide, posing threats to human health and the environment. Although researchers proposed replacing petroleum-based diesel with bio-based diesel, technical, environmental, and economic challenges make their sustainability questionable. In line with that, more sustainable techniques have been introduced to reduce the toxic gas emissions from diesel combustion. Modifying diesel properties using fuel additives or reformulation is a straightforward and economical alternative among these techniques. Various additives, such as oxygenated, cetane number improvers, metal-based compounds, antioxidants, lubricity improvers, and cold flow improvers, are commercially used to improve diesel properties. Among these, higher alcohols as oxygenated additives due to their higher oxygen content and latent heat than diesel can shift the combustion process toward lower temperatures, lowering particulate matter and nitrogen oxide emissions. Despite the promising results offered by higher alcohols as fuel additives for diesel, the sustainability of their production from an environmental, economic, and social point of view should not be neglected. In better words, the decision-making process should not focus on the effects of higher alcohols on exhaust pollutants only, but also it should consider the principles of sustainable development in the background process of higher alcohols, that is, a cradle-to-grave approach. Life cycle sustainability assessment is a valuable tool to address this problem through systematical evaluation of environmental, economic, and social background processes or production of higher alcohols. This chapter aims to better understand the environmental, economic, and social aspects of higher alcohol production based on a life cycle sustainability assessment approach.