The intensification of human and industrial activities since the Industrial Revolution has led to a significant increase in global greenhouse gas emissions, posing a threat to life on our planet. As the transportation sector contributes to 23% of global CO2 emissions, it is imperative to reduce its carbon footprint. Developing a worldwide sustainable biofuel production chain is crucial for this purpose. The Biomass4transport project, a collaboration between TU Delft and the Biomass Technology Group, aims to achieve this by focusing on the production of second-generation biofuels in the Dutch context.

In this context, a techno-economic analysis of a Power and Biomass to Liquid (PBtL) plant that incorporates water electrolysis, pyrolysis oil gasification, and synthesis gas upgrading for gasoline production is presented.
The PBtL plant processes 5000 kg/h of pine wood-derived pyrolysis oil, which undergoes gasification in an oxygen-blown entrained flow gasifier. Subsequent purification steps include cyclones, filters, for the removal of particulate matter and solid ZnO sorbents for the removal of H2S. A solid oxide electrolysis cell produces hydrogen and oxygen streams; the former adjusts the H2:COx ratio before syngas upgrading, while the latter serves as an oxidizing agent in the gasifier. The synthesis gas is converted to dimethyl ether (DME) in a one-step direct conversion membrane reactor, enabling in-situ water removal and enhanced conversion performance. In a subsequent reactor, DME is upgraded to a hydrocarbon mixture, which is further processed to obtain gasoline and LPG.

The process has been modelled by integrating Aspen Plus, Matlab - where an isothermal plug flow membrane reactor model has been coded - and Excel. Material recycling and heat integration strategies have been employed to enhance the plant’s performance in terms of product yield and energy efficiency.

Finally, an economic analysis entailing the calculation of the Net Present Value (NPV) of the plant has been conducted, to assess the conditions under which the plant becomes profitable.

The process has an energy efficiency of 51.8% but could potentially rise to 61.8% with an optimized strategy for hydrogen extraction from the sweep gas of the DME membrane reactor. Due to the absence of CO2 extraction along the process, the carbon efficiency of the process is 95.7%. Both values are higher than the ones of PBtL processes based on hydrogen-enhanced methanol-to-gasoline processes found in literature.

Additionally, the economic analysis showed that the plant is not profitable in the current market conditions. However, with a decline in the price of electricity and/or a reduction in the taxation rate for gasoline, the plant could become profitable, as shown by the sensitivity analysis on the NPV.