BECCS based on bioethanol from wood residues: Potential towards a carbon-negative transport and side-effects

Bioenergy with carbon capture and storage (BECCS) is gaining broad interest as an effective strategy to go beyond carbon neutrality. So far, most of the work on BECCS focused on power systems, while its application to the transport sector has received much less attention. To contribute to filling this gap, this work investigates the potential of BECCS as a carbon-negative strategy in the transport sector by applying process modelling and life cycle assessment (LCA) to bioethanol production from lignocellulosic waste. The process was analyzed following a cradle-to-wheel approach, i.e., from biomass growth to the combustion of biofuel in the cars, assuming that the CO2 emitted in the fermentation and cogeneration units is captured, compressed and transported to be stored permanently in geological sites. Several scenarios differing in the bioethanol-gasoline blends (10-85% bioethanol) were considered for a functional unit of 1 km of distance travelled, comparing with fossil-based gasoline. Our results show that blends above 85% (ethanol/gasoline) could have the potential to deliver a net negative emissions balance of -2.74 kg CO2 eq per 100 km travelled and up to -5.05 kg CO2 eq per 100 km using a low carbon electricity source. The final amount of net CO2 removal is highly dependent on the carbon intensity of the electricity and the heating utilities. Biofuels blends could, however, lead to burden-shifting in eutrophication, ozone depletion and formation, toxicity, land use, and water consumption. This work highlights the potential of BECCS in the transport sector, and the need to analyze impacts beyond climate change in future studies to avoid shifting burdens to other categories.