Life Cycle Assessment of chosen Biochemicals and Bio-based polymers

Abstract

Modern societies are dependent on fossil-based resources, which are limited, and the processing of those resources has proven to be the main cause of climate change, leading to a global warming of the earth. We feel and see the devastating effects of this on our lives and this will keep on happening into the foreseen future if we do not try to change the way we live and make things. We therefore face the question “what else can we humans use to produce the things we rely on in our everyday life, which today we mostly make from petrochemicals, converted from fossil resources?” Scientists, companies, and people in general, are coming up with new ideas on how to produce the same things from alternative resources, and one of them is that some of the solutions can be found in the bioeconomy. The bioeconomy offers that instead of relying on fossil resources in the production of for example chemicals, they can be produced with microbial fermentation, using renewable resources, i.e. biomass, as feedstocks for the microbes. Biochemical production is first and foremost market driven, requesting that the producers can make profit out of their business, so there is a lot of interest in the new and fast-growing market for biochemicals. The general notion about biochemicals is that they are by definition environmentally sustainable, because they are bio-based. Scientific literature mirrors this when stating the environmental sustainability of biochemicals, without presenting conclusive results from environmental assessments supporting these statements. Because of the problems, we are facing regarding the earth warming up, now it is time to change this, because the intention is to produce chemicals from renewable, bio-based resources, and actually make them environmentally sustainable. We need to start incorporating environmental sustainability in the development and optimization of biochemicals at a very early stage, by integrating Life Cycle Assessment (LCA) as both a decision support tool when deciding which future biochemicals to produce, and how to produce them. This should be done in parallel when assessing their technical and economic feasibility, given that is already the general practice. Integrating life cycle assessment in the development of biochemicals will also give us the opportunity, at an early stage of development, to identify environmental hotspots across the whole life cycle of the developed products. Then, we can catch tradeoffs and burden shifting between the assessed environmental impacts, and between the assessed life cycle stages, and instead avoid them in the early stages of development before making large investments to scale up the production, causing unnecessary environmental impacts. Only by doing so, biochemicals become a viable environmentally sustainable alternative. The first steps toward integrating LCA in optimization and decision support for bio-based chemical production are put forward within a decision support framework, presented in this PhD dissertation. To address the need of considering environmental sustainability in decision making by integrating LCA as a decision support tool, the PhD project “Life Cycle Assessment of chosen Biochemicals and Bio-polymers” focuses on answering the overarching question “How can the environmental sustainability of biochemicals, including bio-polymers, be consistently and comprehensively quantified?”. The conclusion is that in order to optimize biochemicals for environmental sustainability, we should start assessing their performance by applying LCA at an early stage, in combination with the assessment of their technical and economic feasibility, by integrating currently applied Techno-economic assessments (TEA) and LCA together. That will lead to an overarching optimization between environmental and economic impacts. This dissertation builds on three papers (schematic overview given here to the right). A short description of the papers is as follows. Paper I gives an overview of the state and challenges of five chosen biochemicals, following recommendations of how preferably to conduct LCAs on biochemicals. Paper II assesses the environmental performance of lactic acid production from three different biofeedstock generations and demonstrates how to use the LCA results for optimization of environmental performance and the effects of uncertainty on interpretation of results. Paper III shows how to integrate LCA as a decision support tool, combined with the application of TEA within a combined decision support framework. The structure of the dissertation is as follows. It comprises of six chapters, and each chapter is subdivided into a different number of sections and sub-sections. The first chapter, the introduction, states the background of the PhD dissertation. Then the different feedstock generations and the biorefinery concept are defined, followed by setting the focus of the PhD project. Chapter two states the overall objectives of the PhD dissertation, followed by three subsections, each giving a short introduction to the objectives of the three papers and research questions that shape the frame of the PhD project. Chapters three, four, and five are the results of the dissertation, reflecting how LCA is applied in the literature, demonstrate how we should apply LCA as a decision support tool, and then how the integrated decision support framework of LCA is combined the Techno-economic assessment. In chapter three, the overview of the current status of LCA studies is presented, based on a review of fourteen different biochemicals that have in common that they are all produced through bacterial fermentation. Of the fourteen biochemicals, special focus is set on five fully commercialized biochemicals, namely Lactic acid, Succinic acid, 1,3-Propanediol, 1,4-Butanediol, and 1,5-Pentanediamine. This is done to get an overview of current practices when assessing the environmental sustainability of biochemicals, their state and current challenges. The results of the chapter conclude that we need to assess the environmental sustainability of biochemicals across all life cycle stages, including end-of-life treatment, and assess all impacts. This has to be done in order to address all relevant burden shifting consistently across life cycle stages and to avoid tradeoffs between different environmental impacts. The chapter then provides guidelines of how to improve LCA practices when assessing biochemicals and how to make the biochemicals industry more environmentally sustainable. In chapter four, I demonstrate how to apply the LCA methodology to identify environmental hotspots when producing lactic acid from three different bio-feedstock generations. There is a special focus on the third feedstock generation, the least developed with the lowest technological readiness level, to demonstrate how to use LCA results to point out process optimization potential, and state how, including the uncertainty of the data, it can affect the interpretation of the results. The inventories for the biorefinery life cycle stage in the LCA are achieved by doing a techno-economic assessment. Firstly, this makes it possible for LCA practitioners to acquire the needed inventories, which often are not available in the literature, and to make the study results more robust. Secondly, as becomes clear in the case of my study, applying TEA also helps scaling up the different feedstock generation processes to the same production volume and makes an assessment like this possible, when access to industrial data is limited. Chapter five presents an integrated framework how to consistently couple environmental and economic indicators to allow for an overall optimization at early development stages of biochemical production within a decision support framework. The framework is stepwise introduced starting with a discussion on why we need to start looking beyond economic assessments, followed by a short introduction of current application of LCA and TEA, both separately and combined. The last two sections of chapter five describe the structure of the developed integrated framework and the results of a combined LCA and TEA representing the results demonstrating how to couple environmental and economic indicators in an economic single score. Chapter six concludes the work and addresses future research needs beyond the scope of the present PhD dissertation. The impact of the PhD project is to help understanding how to make biochemicals and derived bio polymers more environmentally sustainable by identifying their most relevant optimization potential (LCA across generations) and integrate environmental aspects into decision processes (integrate LCA and TEA). In the different sections and sub-sections of this dissertation, some figures and tables are identical to the ones presented in the publications laying the foundations of this dissertation, and they are cited by marking them with the roman numbers of each publication presented in this dissertation summary. If text is reused from the listed publications in the PhD dissertation summary, the same procedure is followed as mentioned before, and it is also clearly stated in the beginning of the chapter. This is done to be transparent about the originality of a text, as is practiced when citing other people’s work.