(149c) Techno-Economic and Life Cycle Analysis of Dimethyl Ether Production Via the Bi-Reforming Pathway for Transportation Fuel

Dimethyl-ether (DME) is a diesel fuel-substitute commercially produced via Natural Gas (NG) reforming. This approach is economical but generates significant greenhouse gas (GHG) emissions. This study investigates the Techno-economic (TEA) and Life Cycle Assessment (LCA) of DME production via bi-reforming of waste CO₂ streams and methanol synthesis and dehydration.

A conceptual DME production plant with a 500 metric tonne per day capacity is simulated in Aspen Plus^TM. In the model, CO₂ is sourced from either an Ammonia production facility (CFA) or from Landfill gas (CFL). The TEA evaluates the DME minimum fuel-selling price (MFSP) over a 30-year project lifetime with a 12% internal rate of return. The LCA estimates the well-to-pump GHG emissions using GREET.net over a 100-year horizon. TEA and LCA results are compared to conventional diesel production. Sensitivity analysis of the MFSP to key TEA parameters including DME production, capital cost, and CO₂ price is investigated.

The estimated minimum fuel-selling price (MFSP) is $1.03 and $1.05/gal for the CFA and CFL cases, respectively. The equivalent diesel price ranges from $1.93 to $1.96/gal, which would be competitive with the market price of conventional diesel fuel. The well-to-pump lifecycle analysis shows that emissions range from -38.2 to 34.8 kg CO₂ eq/MMBtu. Using landfill gas sourced CO₂, the process achieves negative emissions by avoiding the release of more potent GHGs whereas using CO₂ from an ammonia plant results in higher emissions than conventional diesel (17.7 kg CO₂ eq/MMBtu). These results indicate that bi-reforming could be an economical and sustainable pathway for DME production as a diesel substitute.