Aiduan Li Borrion

Use of LCA as a development tool within early research: challenges and issues across different sectors

PurposeThe aim of this paper is to highlight the challenges that face the use of life cycle assessment (LCA) for the development of emerging technologies. LCA has great potential for driving the development of products and processes with improved environmental credentials when used at the early research stage, not only to compare novel processing with existing commercial alternatives but to help identify environmental hotspots. Its use in this way does however provide methodological and practical difficulties, often exacerbated by the speed of analysis required to enable development decisions to be made. Awareness and understanding of the difficulties in such cases is vital for all involved with the development cycle.MethodsThis paper employs three case studies across the diverse sectors of nanotechnology, lignocellulosic ethanol (biofuel), and novel food processes demonstrating both the synergy of issues across different sectors and highlighting the challenges when applying LCA for early research. Whilst several researchers have previously highlighted some of the issues with use of LCA techniques at an early stage, most have focused on a specific product, process development, or sector. The use of the three case studies here is specifically designed to highlight conclusively that such issues are prevalent to use of LCA in early research irrespective of the technology being assessed.Results and discussionThe four focus areas for the paper are system boundaries, scaling issues, data availability, and uncertainty. Whilst some of the issues identified will be familiar to all LCA practitioners as problems shared with standard LCAs, their importance and difficulty is compounded by factors distinct to novel processes as emerging technology is often associated with unknown future applications, unknown industrial scales, and wider data gaps that contribute to the level of LCA uncertainty. These issues, in addition with others that are distinct to novel applications, such as the challenges of comparing laboratory scale data with well-established commercial processing, are exacerbated by the requirement for rapid analysis to enable development decisions to be made.ConclusionsBased on the challenges and issues highlighted via illustration through the three case studies, it is clear that whilst transparency of information is paramount for standard LCAs, the sensitivities, complexities, and uncertainties surrounding LCAs for early research are critical. Full reporting and understanding of these must be established prior to utilising such data as part of the development cycle.

Challenge clusters facing LCA in environmental decision-making—what we can learn from biofuels

PurposeBioenergy is increasingly used to help meet greenhouse gas (GHG) and renewable energy targets. However, bioenergy’s sustainability has been questioned, resulting in increasing use of life cycle assessment (LCA). Bioenergy systems are global and complex, and market forces can result in significant changes, relevant to LCA and policy. The goal of this paper is to illustrate the complexities associated with LCA, with particular focus on bioenergy and associated policy development, so that its use can more effectively inform policymakers.MethodsThe review is based on the results from a series of workshops focused on bioenergy life cycle assessment. Expert submissions were compiled and categorized within the first two workshops. Over 100 issues emerged. Accounting for redundancies and close similarities in the list, this reduced to around 60 challenges, many of which are deeply interrelated. Some of these issues were then explored further at a policy-facing workshop in London, UK. The authors applied a rigorous approach to categorize the challenges identified to be at the intersection of biofuels/bioenergy LCA and policy.Results and discussionThe credibility of LCA is core to its use in policy. Even LCAs that comply with ISO standards and policy and regulatory instruments leave a great deal of scope for interpretation and flexibility. Within the bioenergy sector, this has led to frustration and at times a lack of obvious direction. This paper identifies the main challenge clusters: overarching issues, application and practice and value and ethical judgments. Many of these are reflective of the transition from application of LCA to assess individual products or systems to the wider approach that is becoming more common. Uncertainty in impact assessment strongly influences planning and compliance due to challenges in assigning accountability, and communicating the inherent complexity and uncertainty within bioenergy is becoming of greater importance.ConclusionsThe emergence of LCA in bioenergy governance is particularly significant because other sectors are likely to transition to similar governance models. LCA is being stretched to accommodate complex and broad policy-relevant questions, seeking to incorporate externalities that have major implications for long-term sustainability. As policy increasingly relies on LCA, the strains placed on the methodology are becoming both clearer and impedimentary. The implications for energy policy, and in particular bioenergy, are large.

Effects of organic composition on mesophilic anaerobic digestion of food waste

Anaerobic digestion of food waste (FW) has been widely investigated, however, little is known about the influence of organic composition on the FW digestion process. This study aims to identify the optimum composition ratios of carbohydrate (CA), protein (CP) and lipid (EE) for maintaining high methane yield and process stability. The results show that the CA-CP-EE ratio was significantly correlated with performance and degradability parameters. Controlling the CA-CP-EE ratio higher than 1.89 (CA higher than 8.3%, CP lower than 5.0%, and EE lower than 5.6%) could be an effective way to maintain stable digestion and achieve higher methane production (385-627mL/gVS) and shorter digestion retention (196-409h). The CA-CP-EE ratio could be used as an important indicator for digestion performance. To effectively evaluate organic reduction, the concentration and removal efficiency of organic compositions in both solid phases and total FW should be considered.

Process characteristics for microwave assisted hydrothermal carbonization of cellulose

The process characteristics of microwave assisted hydrothermal carbonization of cellulose was investigated and a first order kinetics model based on carbon concentration was developed. Chemical properties analysis showed that comparing to conventional hydrothermal carbonization, hydrochar with comparable energy properties can be obtained with 5-10 times decrease in reaction time with assistance of microwave heating. Results from kinetics study was in great agreement with experimental analysis, that they both illustrated the predominant mechanism of the reaction depend on variations in the reaction rates of two co-existent pathways. Particularly, the pyrolysis-like intramolecular dehydration reaction was proved to be the predominant mechanism for hydrochar generation under high temperatures. Finally, the enhancement effects of microwave heating were reflected under both soluble and solid pathways in this research, suggesting microwave-assisted hydrothermal carbonization as a more attracting method for carbon-enriched hydrochar recovery.

Effects of organic composition on the anaerobic biodegradability of food waste

This work investigated the influence of carbohydrates, proteins and lipids on the anaerobic digestion of food waste (FW) and the relationship between the parameters characterising digestion. Increasing the concentrations of proteins and lipids, and decreasing carbohydrate content in FW, led to high buffering capacity, reduction of proteins (52.7-65.0%) and lipids (57.4-88.2%), and methane production (385-627 mLCH4/g volatile solid), while achieving a short retention time. There were no significant correlations between the reduction of organics, hydrolysis rate constant (0.25-0.66d-1) and composition of organics. Principal Component Analysis revealed that lipid, C, and N contents as well as the C/N ratio were the principal components for digestion. In addition, methane yield, the final concentrations of total ammonia nitrogen and free ammonia nitrogen, final pH values, and the reduction of proteins and lipids could be predicted by a second-order polynomial model, in terms of the protein and lipid weight fraction.

ADM1 Modelling of large-scale covered in-ground anaerobic reactor treating sugarcane vinasse

In this paper, we demonstrate in a clear procedure the application of the Anaerobic Digestion Model No. 1 (ADM1) to model a large-scale covered in-ground anaerobic reactor (Cigar), processing sugarcane vinasse from a biorefinery in Brazil. The biochemical make-up (carbohydrates, proteins, and lipids) of the substrate was analysed based on the food industry standards. Two distinct subsets of data, based on the sugarcane harvest season for bioethanol and sugar production in 2012 and 2014, were used to direct and cross validate the model, respectively. We fitted measured data by estimating two key parameters against biogas flow rate: the degradation extent (fd) and the first order hydrolysis rate coefficient (khyd). By cross validation we show that the fitted model can be generalised to represent the behaviour of the reactor under study. Therefore, motivated by practical and industrial application of ADM1, for both different reactors types and substrates, we show aspects on the implementation of ADM1 to a specific large-scale reactor for anaerobic digestion of sugarcane vinasse.

Influence of feed/inoculum ratios and waste cooking oil content on the mesophilic anaerobic digestion of food waste

Information on the anaerobic digestion (AD) of food waste (FW) with different waste cooking oil contents is limited in terms of the effect of the initial substrate concentrations. In this work, batch tests were performed to evaluate the combined effects of waste cooking oil content (33-53%) and feed/inoculum (F/I) ratios (0.5-1.2) on biogas/methane yield, process stability parameters and organics reduction during the FW AD. Both waste cooking oil and the inoculation ratios were found to affect digestion parameters during the AD process start-up and the F/I ratio was the predominant factor affecting AD after the start-up phase. The possible inhibition due to acidification caused by volatile fatty acids accumulation, low pH values and long-chain fatty acids was reversible. The characteristics of the final digestate indicated a stable anaerobic system, whereas samples with F/I ratios ranging from 0.8 to 1.2 display higher propionic and valeric acid contents and high amounts of total ammonia nitrogen and free ammonia nitrogen. Overall, F/I ratios higher than 0.70 caused inhibition and resulted in low biogas/methane yields from the FW.

Development of LCA Calculator to support community infrastructure co-design

PurposeLCA tools are increasingly used to support decision making. However, the current generation of tools is mainly targeted at users with significant background in industrial and environmental processes. This paper presents a novel process of developing the LCA Calculator with inputs from community members embedded in a co-design process. It demonstrates how engineering tools can be developed by considering end-user perspectives and used to communicate systems thinking in infrastructure co-design.MethodsThe process of the LCA Calculator development was informed by the outcomes of community engagement through the co-design process. The method consists of four parts including horizon scanning of suitable technology options, LCA modelling, development of the LCA Calculator and pilot testing of the Calculator with residents from the selected case study community. The case study community are residents of a social housing estate in central London. The estate has a total of 123 flats arranged in three low-rise blocks with shared gardens and courtyards. Three technology options—wormery composting, rainwater harvesting and urban food growing—were used to illustrate the LCA methods and test the Calculator development.Results and discussionThe Calculator developed in this project pushes the boundaries beyond expert users to develop a new generation of LCA tools for a wider range of decision makers. The LCA results were communicated using the LCA Calculator in a workshop as part of the co-design process. The communication process was supported by the visual language of the Calculator, information sheets of the technology options and community members’ involvement in the process of the Calculator development. The Calculator provided a solid base on which sustainable design discussions could happen. It provided to the participants valuable insights into the scale of material flow given different design choices—such as the amount of waste generated over a month or the irrigation requirements of a raised bed—and environmental impacts of these options.ConclusionsA prototype version of an LCA Calculator software tool has been developed to enable rapid assessment of conceptual design of engineering systems. The LCA Calculator was successfully tested at a community workshop, enabling clear engagement between engineering design choices and resource and environmental impacts. The Calculator facilitated a two-way exchange between community members and infrastructure designers that embeds end-user perspectives in the design and implementation of the infrastructure they use, taking into account lifecycle impacts of technology and material options.

Corrigendum to “Effects of organic composition on mesophilic anaerobic digestion of food waste” [Bioresour. Technol. 244 (2017) 213–224]

Yangyang Li, Yiying Jin, Aiduan Borrion, Hailong Li, Jinhui Li (2017) Effects of organic composition on mesophilic anaerobic digestion of food waste, Bioresource Technology, Volume 244, Part 1, November 2017, Pages 213-224 (https://doi.org/10.1016/j.biortech.2017.07.006)