Ranjan Parajuli has conducted his Ph.D. thesis in the BioValue project: Socio-economics, Sustainability and Ethics (SeSE). Below is a summary of his findings and an invitation to the defense.  

Author: Ranjan Parajuli, Dept. of Agroecology, Aarhus University

The environmental impacts of biomass production, the security and stability of supplies, and the need to diversify biomass use are all important issues for the further development of biobased value chains for addressing the current debates on fuel versus food and fiber productions. In this context, the development of biorefinery technologies can add value to the biomass conversion by co-producing both fuel and non-fuel products. Therefore, evaluating general performance of biorefinery value chains and considering critical environmental and socio-economic paradigms is relevant to support decision-making, when various value chains have to be screened for devising necessary policy measures, investments, etc.

This Ph.D. study thus aimed at answering whether the utilization of biomasses for biorefinery purposes has significant impacts on the environmental sustainability. It first prioritized biomass types and biorefinery platforms for a detail sustainability assessment by highlighting the important research perspectives in the sector. Latter, a multi-criteria decision analysis method, was used to pre-screen the lignocellulosic biomasses for biorefineries. An evaluation was made on indicators, e.g. supply potential, properties and potential environmental gain/losses related to biomass production. The initial screening of biomasses stressed for accounting a detailed input-output modeling of an agricultural system, as agriculture-based emissions and yields are dependent on specific agro-climatic parameters and agricultural management practices.

The study then assessed environmental footprints of seven different crops using the Life Cycle Assessment (LCA) method. The biomasses were: grass-clover, ryegrass, alfalfa, willow, maize and straw from winter wheat and spring barley. Regarding the environmental performance of biomass production, the different biomasses showed mixed results. E.g., grass-clover, and ryegrass had higher carbon footprint compared to willow, while the freshwater ecotoxicity was lower. Alfalfa had a little environmental impact across all impact categories. The least negative impact on biodiversity was found in grass-clover followed by grasses in general, compared to e.g. maize.

Lastly, the study focussed on LCAs of two biorefinery value chains: (i) conversion of alfalfa in a green biorefinery technology, producing biobased lactic acid, as the main product and (ii) conversion of winter wheat straw to bioethanol. Both attributional (economic allocation) and consequential approaches were used. The results showed that bioethanol and biobased lactic acid had net savings regarding GHG emissions and fossil fuel use compared to petrol and conventional lactic acid.

The environmental assessments highlighted that it is important to consider a broad range of environmental impact categories rather only a single indicator to avoid sub-optimization in the decision support e.g. for policy making. The study furthermore highlighted the importance of accounting for soil carbon changes and management of nutrients in the agricultural system. For biorefineries energy input and impacts related to the enzyme production contributed the most to the selected environmental impact categories. However, there were advantages from recirculation of intermediate raw materials and industrial symbiosis, e.g. integrating biorefinery technologies to reduce the environmental impacts. The results based on consequential and attributional approaches arrived at similar conclusions for biobased products; hence the decision to be made based on their effects would be the same.

The primary motivation for the Ph.D. study and my future career here is to reveal the interactions between technology and management practices for the better utilization of natural resources. Screening of different biobased products regarding their environmental and economic footprints are necessary to introduce biobased products in the fossil-fuel based products.


I would like to contribute further on such perspectives – and invite you to participate at my defense:

Time: Wednesday 11 January 2017 at 12.30

Place: Auditorium, AU-Foulum, Blichers Allé 20, 8830 Tjele

Defense Title: Environmental impact of biorefinery feedstocks and biobased products