(741a) Jatropha-Based Biorefinery Integrating Chemical and Thermochemical Platforms for the Co-Production of Biofuel, Bioenergy and Chemicals

Authors: 
Martinez-Hernandez, E., University of Bath
Sadhukhan, J., The University of Surrey
Campbell, G. M., The University of Manchester



Renewability and the carbonaceous basis of biomass provide potential for both energy and chemical production in biorefineries in a fashion similar to crude oil refineries. Biorefineries are envisaged as having a key role in the transition to a more sustainable industry, especially as a means to mitigate greenhouse gas (GHG) emissions. A biorefinery is a concept for the flexible, efficient, cost-effective and sustainable conversion of biomass through a combination of process technologies into multiple products1. This implies that biorefineries must be integrated through designs that exploit the interactions between material and energy streams.

         The wide range of possibilities for biomass feedstock, processes and products poses a challenge to biorefinery design. Integrating biorefineries within evolving economic and environmental policy contexts requires careful analysis of the configurations to be deployed from early in the design stage. This research therefore focuses on the application of methodologies for biorefinery design (process integration tools, economic and environmental sustainability analyses together).

         Using Jatropha seeds as main biorefinery feedstock, integrated systems are explored for the production of biodiesel and value added co-products such as methanol and propylene glycol using thermochemical processes. The integration strategy included the utilisation of seed husk (a lignocellulosic residue) in an integrated biomass gasification system for the co-production of heat and power, hydrogen and methanol. Heat and power is supplied to the various conversion processes while the methanol is provided for the conversion of Jatropha oil into biodiesel and hydrogen is provided for the conversion of glycerol into propylene glycol. The possibility to export excess electricity and methanol are explored.

         The integration of the process technologies and platforms allows the Jatropha-based biorefinery to be self-sufficient in both energy and major auxiliary raw material (methanol) leading to process designs with low GHG emissions and low fossil primary energy use. This is due to the substantial avoided emissions from replacement of fossil-based energy and raw materials, both internally due to process integration and externally due to the export of excess bioenergy or methanol. The economic feasibility is evaluated along with the environmental sustainability in terms of GHG emissions using a combined economic value and environmental impact (EVEI) analysis tool2.

         The EVEI analysis tool is a multi-level methodology that incorporates process and feedstock production models alongside models at the economic and environmental impact levels, the effects of process integration and co-evolutionary agronomic and process technologies, economic market and sustainability criteria. As a result, the simple yet robust methodology is a helpful tool for analysing overall biorefinery performance in a systematic manner. At the same time, it enables insights to be transferred into foresight applications such as system hot spots identification, scenario building, generation of innovative process integration routes, trade-off evaluation between economics and environmental impact as well as future policy compliance and recommendations.

         This work demonstrates how the chemical engineering concepts can be used in favour of biorefinery development. It also highlights the benefits from the full exploitation of a feedstock by integrating various processes that convert the whole ton of biomass into value added products in a biorefinery (as the whole barrel of crude oil is converted into value added products in a conventional refinery). In doing so, wastes are reduced and better utilised thus reducing emissions and fossil energy depletion. The use of thermochemical processes allows ready transition to renewable feedstocks by adaptation of mature and proven technologies in the natural gas, carbon and crude oil refining industries such as gasification and hydrotreatment. Furthermore, a thermochemical platform offers flexibility in the generation of both heat and power and other important biorefinery raw materials such as methanol and hydrogen while also giving scope for the export of any excess electricity and value added products, which provides further environmental credits due to replacement of fossil-based products.

1. Kamm, B. and Kamm, M., 2005. Appl Microbiol Biotechnol 64, 137−145.

2. Martinez-Hernandez, E., Campbell, G.M., Sadhukhan, J., 2013. Chem Eng Res Des, In Press.