Simulations of bio-oil refinement can improve production efficiency

In the pursuit of renewable energy sources, bio-oil offers a promising alternative to petroleum. Created from biomass products like tree bark and waste wood, bio-oil can be used in power plants to reduce greenhouse gas emissions and increase energy security.

Currently, fast pyrolysis — a process of burning biomass anaerobically — is the most cost-effective and efficient way to create biofuels. Bio-oil must additionally be upgraded through hydrodeoxygenation to create a high-quality fuel. In a new study, Lv et al. simulated the fast pyrolysis and hydrodeoxygenation processes to help energy-producing plants increase production efficiency.

The study looked at the maximum total energy that can be extracted from a system in the processes in order to optimize energy efficiency. Using Aspen Plus, a simulation software, the researchers tested different ways to increase exergetic performance during the production of bio-oil. The results found fast pyrolysis was more efficient than other fuel conversion processes, and identified five areas that can offer increased production efficiency.

Overall, the exergetic efficiency is 49 percent, but if byproducts from production, which have many useful applications, are considered, the efficiency rises to 57 percent. The greatest increase in efficiency comes from matching the heat of the pyrolysis reaction to that of the partially combusted char, one of the byproducts, and collecting the unburnt fraction as a solid product.

An additional benefit comes from reducing system pressure, producing hydrogen on-site, and recovering heat from exhaust gas. The authors are continuing to improve solutions to be more suitable for industrial production.

Source: “Quantifying the exergetic performance of bio-fuel production process including fast pyrolysis and bio-oil hydrodeoxygenation,” by Qizheng Lv, Hui Yue, Qixiang Xu, Changsen Zhang, and Ruiqin Zhang, Journal of Renewable and Sustainable Energy (2018). The article can be accessed at https://doi.org/10.1063/1.5031894 .