This study aims to design and evaluate the techno-economic feasibility of socially just and context-specific biohubs for producing marine biofuels based on olive residues with hydrothermal liquefaction (HTL) in Spain, using existing infrastructures. The conceptual process and biohubs design are co-designed using a multi-actor approach, involving local stakeholders through participatory methods, with the help of a Capability-sensitive design. The material and energy balances (from Aspen Plus simulations) are used to evaluate the technical and economic performance (such as capital expenses, operational costs, and minimum fuel selling price) of biohub. 21 possible scenarios are investigated to understand the impact of design aspects (such as scale, distributed configuration, and co-processing) on the minimum fuel selling price (MFSP). The MFSP of the HTL biofuels varied by a factor of 0.6–3.1 compared to the conventional fossil-based fuels. Additionally, co-processing of HTL bio-crude at existing petroleum refineries reduces equipment costs by 16%. The study also recommends that the minimum scale of the HTL facilities should be between 588–882 dry tons per day (DTPD) of crude olive pomace processing capacity, to benefit from economies of scale. Overall, the investigation shows an economically feasible way to develop context-relevant olive residue-based biohubs for marine biofuel production with existing infrastructures in Spain, while ensuring social justice near biomass production sites. We argue this approach can be replicated in the other olive-producing regions in the Mediterranean and conclude that olive residues from the Mediterranean region have a huge potential to provide alternative advanced “drop-in” biofuels for the shipping sector.

Promoting inclusive development through public policies is a complex task that presents different challenges and even controversies. The National Program for Biodiesel Production and Use (PNPB) in Brazil is one example of an effort to promote sustainable development within an inclusive strategy with good intentions but many challenges. One of the PNPB goals is to diversify feedstocks for biodiesel production, and oils from the Acrocomia spp. palm genus have the potential to meet this goal. As acrocomia's value chain is under development in Brazil, particularly with a focus on the macaúba palm (Acrocomia aculeata), and in different regions of Latin America, we state that it is possible to develop it with the inclusion of smallholder farmers. In this sense, this paper focuses on analyzing the challenges and opportunities for smallholder productive inclusion in the value chain. Our main question is: How can the participation of smallholders in the cultivation of macaw palm be promoted? The answer to this question is based on literature and field research carried out by the authors. Our study finds opportunities for inclusion, but also four main challenges to be considered with caution: i) the shift from agroextractivism to commercial plantations, ii) the limited acreage available to some small farmers, iii) the slow pace in generating economic results, and iv) negative past experiences with other crops. We emphasize the importance of development strategies that offer incentives, mitigate risks, and guarantee greater security in decision-making for those involved. The available literature about the acrocomia value chain focuses mainly on technical and agronomic aspects, with few outputs on inclusion. In this sense, this paper calls attention to the development of the novel biobased value chains from the acrocomia palm without leaving social responsibility behind.

Bio-based value chains (BBVCs) have often been criticized for their detrimental social and environmental effects. Existing methods such as social impact assessment do not sufficiently address these negative effects because of their limited focus and lack of attention to social justice. This paper explores the contribution of Capability Sensitive Design (CSD) to designing BBVCs for social justice. CSD is a combination of Value Sensitive Design (VSD), an approach to account for human values in a design process, and the Capability Approach (CA), a normative framework that incorporates multiple dimensions of human well-being. Three case studies demonstrate how CSD can be used to make design choices in the early stages of developing new BBVCs from waste biomass. The cases explore olive oil residues in Spain, coffee and cocoa residues in Colombia, and encroacher bush in Namibia. CSD is a relatively new approach and its contribution to social justice in BBVCs remained unexplored. We show that CSD can contribute to distributive, recognition, and procedural justice by allowing the identification of local vulnerable stakeholders and providing tools to connect their needs, knowledge, and capabilities to concrete design choices.

Biomass such as crops and agricultural waste is increasingly used as the primary resource for products like bioplastics and biofuels. Incorporating the needs, knowledge, skills and values of biomass producers in the design of global value chains – the steps involved in creating any finished product from design to delivery – can contribute to sustainability, reliability and fairness. However, how to involve biomass producers, especially if they are resource poor, remains a challenge. To make sure that inclusion in global biobased value chains is both fair and effective, the capabilities of relevant actors need to be taken into account, especially of those producing biomass. Access to resources determines to what extent a specific actor can participate in a global value chain. Therefore, differences in capabilities should be a central consideration when new (biobased) value chains are designed. Using the capability approach as an ethical framework to realize inclusion, we discern three complementary strategies for setting up inclusive value chains. Firstly, designing for local conversion factors second, providing adaptive design for new capabilities, and third, investing in local conversion factors. Applying these strategies can lead to context-sensitive design of biorefineries that allow for true inclusion of local stakeholders. We support these claims with reference to case-studies of sugarcane production in Jamaica, modified tobacco in South Africa and the non-edible parts of corn (stover) in the US.

The recovery of resources, including water reuse, has been presented as a solution to overcome scarcity, and improve the economic and environmental performance of water provision and treatment. However, its implementation faces non-technical challenges, including the need to collaborate with new stakeholders and face societal acceptance issues. Looking at the prominence of the circular economy in current policy developments and the challenges to resource recovery, exploring these issues is urgently needed. In this work, we reviewed a broad range of literature to identify societal values relevant to the recovery of water and other resources from wastewaters, particularly urban and industrial wastewater and desalination brines. We discuss tensions and uncertainties around these values, such as the tension between socio-economic expectations of resource recovery and potential long-term sustainability impacts, as well as uncertainties regarding safety and regulations. For addressing these tensions and uncertainties, we suggest aligning common methods in engineering and the natural sciences with Responsible Innovation approaches, such as Value Sensitive Design and Safe-by-Design. To complement Responsible Innovation, social learning with a Sustainability Transitions or Adaptive Governance perspective is suggested.

Eighty percent of wastewater is left untreated or not reused, exacerbating the water quality challenge, especially in vulnerable communities. This Voices asks: how can we improve wastewater management and convert wastewater into a resource?

Aviation biofuels are promising to reduce carbon emissions in the aviation sector. However, emerging concerns over biofuels indicate a need for sustainability analyses that take into consideration the context around biofuel production. Here, we present a novel ex-ante sustainability analysis of production alternatives for aviation biofuel in Southeast Brazil. Considering local stakeholders’ concerns, the analysis is focused on climate change, commercial acceptability, efficiency, energy security, investment security, profitability, social development, and soil sustainability. By identifying tensions between production alternatives and these sustainability aspects, we discuss opportunities for further developments, such as sugarcane ethanol-to-jet production in the short term, and in-house production of hydrogen and power with renewable energy. Additionally, producer–operator partnerships and opening the decision-making to stakeholder participation are suggested to stimulate social cohesion, and reconcile diverging interests with biobased production. Analyzing sustainability with consideration of the local context can contribute to identify opportunities for more sustainable decarbonization alternatives.

Sustainable aviation fuels (SAF) are fuels that have potential to be sustainably produced and to generate lower carbon emissions when compared to the conventional kerosene. Wider SAF production and utilization represent nowadays an important step to move towards a more sustainable aviation industry, which has committed to significantly reduce their net carbon emissions by 2050. To reach this target, significant efforts have been done to develop sustainable technologies for the production of aviation fuels able to be implemented in a large scale. This chapter summarizes and discusses the different technologies that have been proposed to produce aviation biofuels, their potential to be upscaled and techno-economic perspectives, as well as the impact of SAF on sustainability. At the end, the industry point of view on the prospects for a wider production and use of aviation biofuels is also presented.

The objective of this paper is to compare, under Dutch market conditions, the energy consumption and net costs of membrane-based advanced treatment processes for three water reuse types (i.e. potable, industrial, agricultural reuse). The water source is municipal waste-water treatment plant effluent. Results indicate that the application of reverse osmosis is needed to reclaim high quality water for industrial and potable reuse but not for irrigation water which offers significant energy savings but may not lead automatically to lower net costs. While a reclamation process for industrial reuse is economically most promising, irrigation water reclamation processes are not cost effective due to low water prices. Moreover, process operational expenditures may exceed capital expenditures which is important for tender procedures. A significant cost factor is waste management that may exceed energy costs. Water recovery rates could be significantly enhanced through the integration of a softener/biostabilizer unit prior to reverse osmosis. Moreover, the energy consumption of wastewater reclamation processes could be supplied on-site with solar energy. The possibility of designing a ‘fit for multi-purpose’ reclamation process is discussed briefly. This comparative analysis allows for better informed decision making about which reuse type is preferably targeted in a municipal wastewater reuse project from a process design perspective.

Biobased production has been promoted as an alternative to fossil-based production to mitigate climate change. However, emerging concerns over the sustainability of biobased products have shown that tensions can emerge between different objectives and concerns, like emission reduction targets and food security, and that these are dependent on local contexts. Here we present the Open Sustainability-in-Design (OSiD) framework, the aim of which is to integrate a context-sensitive sustainability analysis in the conceptual design of biobased processes. The framework is illustrated, taking as an example the production of sustainable aviation fuel in southeast Brazil. The OSiD framework is a novel concept that brings the perspectives of stakeholders and considerations of the regional context to an ex ante sustainability analysis of biobased production. This work also illustrates a way to integrate methods from different scientific disciplines supporting the analysis of sustainability and the identification of tensions between different sustainability aspects. Making these tensions explicit early in the development of biobased production can make them more responsive to emerging sustainability concerns. Considering the global pressure to reduce carbon emissions, situating sustainability analyses in their socio-technical contexts as presented here can help to explain and improve the impacts of biobased production in the transition away from fossil resources.

The TRANSCEND project (as part of the Clean Sky 2 Technology Evaluator) aims to develop roadmaps for full scale entry-into-service of selected propulsion technologies and alternative fuels in the period 2035-2050, in line the emission target of FlightPath-2050 for the period 2035-2050. In this work we present the selection of six sustainable aviation fuels (SAFs) that will be included in TRANSCEND road-mapping. The full context of TRANSCEND and its findings for promising propulsion technologies are introduced in the complementary presentation: “Review of novel propulsion technologies for sustainable aviation from TRANSCEND” by Johan Kos. The reviewed SAFs included bio-based fuels and e-fuels as drop-in SAFs, and non-drop-in energy sources (here hydrogen). As part of the literature review, 19 groups of production technologies for SAF were initially identified, from which 5 technologies were discarded in the screening process due to either potential limitations on scalability or it very early technological development stage (i.e. very low Technology Readiness Levels). Subsequently, the 14 remaining technologies were comparatively analyzed for both their unitary production costs (i.e. costs per unit of usable energy [€/MJ]) and unitary greenhouse gas (GHG) emissions (i.e. CO2-eq. per unit of usable energy [CO2-eq./MJ]). As a result, five promising SAF production routes were pre-selected for further discussion with experts in a workshop; and at the end of the session six SAFs were selected for further evaluation in the roadmap, they are: hydroprocessed esters and fatty acids (HEFA), Fisher-Tropsch process (FT), fast pyrolysis (FP), Alcohol to Jet (ATJ), power-to-liquid (PtL) for e-fuel via Fisher-Tropsch, and alkaline electrolysis (AE) for hydrogen. Finally, the data collected on the life cycle GHG emissions, for most the relevant alternative energy sources and production routes, were used to develop an open Microsoft Excel based tool (the “Ecological Balance Sheet”) to quickly estimate a range of expected GHG emissions and the potential emissions savings of a production chain (based on similar systems already reported in literature).

Although the potential of Alternative Jet Fuels (AJF) to reduce greenhouse gases (GHG) emissions has been widely reported upon in the literature, there are still discrepancies among the results. These may be due to the different GHG accounting methods, including those used by different Low-Carbon Policies (LCPs). To have a clearer understanding of the life cycle performance of AJF, the carbon footprint of ten pathways was estimated, comprising promising feedstocks – such as soybean, palm, sugarcane, sugarcane residues, forestry residues, used cooking oil, beef tallow, and steel off-gases – and ASTM-approved technologies: Hydroprocessed Fatty Acids, Alcohol-to-Jet, and Fischer-Tropsch. Six methodological approaches were used: the attributional and the consequential life cycle assessment, as well as guidelines for the four LCPs: Renovabio (Brazil), CORSIA (aviation sector), RFS (United States), and RED II (Europe). Soybean-based pathway (24 to 98.7 gCO_2e/MJ) had the low to no potential for reducing GHG when compared to their fossil counterparts, mainly due to land use change. Of all food-based pathways, AJF produced from sugarcane performed the best (-10.4 to 43.7 gCO_2e/MJ), especially when power surplus was credited. AJF from palm oil could present significant GHG reduction for palm expansion in degraded pasturelands. By contrast, Fischer-Tropsch of lignocellulosic residues showed the highest potential for reducing GHG (-95% to -130%). Different from food-based pathways, the potential GHG reduction of residues-based pathways converged within a narrower range (-130% to -50%), except when residual feedstocks have to be redirected from their current economic use. It could lead to GHG emissions higher than fossil fuel.

More pluralised understandings of incumbencies are often overlooked in transitions research, which may lead to underestimating the enabling roles of incumbents in niche projects. This study explores these roles by applying a power framework to five struggles revolving around a path-breaking decentralised wastewater treatment project in the city of Ghent (Belgium). Remarkably, incumbents from multiple regimes use power to enable the niche project. The study identifies and discusses four patterns in the enabling role of incumbents in niche projects. These patterns are clarified by focussing on incumbents from multiple regimes, belonging to local authorities, neighbouring and more distant regimes, as well as on the power of structural trends related to the urgency of sustainability challenges. As such, the study contributes to the understanding of multiple incumbencies and the conditions under which these may reinforce niche projects. For practitioners, the study underscores the role of power dynamics in the water/wastewater sector.

Environmental problems are usually not tackled with path-departing policies but rather with incrementally adjusted or unchanged policies. One way to address incremental change is the policy feedback approach, which initially focussed on self-reinforcing feedback and path-dependency. Today, self-undermining feedback is also increasingly being studied, centring on agency and change. However, it is unclear precisely how actors use power in policy feedback processes. Therefore, this study applied a power perspective and the policy arrangement approach to a case study of the reorientation towards a circular economy in Dutch wastewater policy between 2008 and 2018, which resulted in incremental instead of fundamental policy change. Here it was observed that self-undermining feedback was generated from 2008 onwards but the balance quickly shifted back to self-reinforcing feedback, indicating that the analysed power struggles led to incremental change. These dynamics resemble a shift from the so-called paths and forks (i.e. fork in the road) towards the boomerang pattern (i.e. returning to its original position) of policy change. The patterns are explained by focussing on powerful actors that resist change through the use of incremental reforms, the ongoing struggles of these actors in facilitating self-reinforcing feedback and the role of interpretation in using feedback as a resource. Overall, this study provides a nuanced understanding of incremental change by directing attention to the power struggles of actors in policy feedback processes. For practitioners, the study emphasises the importance of power struggles in enabling a circular economy.

The life cycle human health (HH) impacts related to aviation biofuels have been understood in a limited way. Life cycle impact assessment (LCIA) methods for assessing HH are often associated with a high level of uncertainty and a low level of consensus. As a result, it remains challenging to perform a robust assessment of HH impacts with a suitable LCIA method. This study aims to systematically compare six commonly used LCIA methods for quantifying HH impacts, in order to empirically understand the potential impacts of aviation biofuel production on HH and how the results are affected by the choice of methods. Three aviation biofuel production pathways based on different feedstocks (sugarcane, eucalyptus, and macauba) were analyzed and compared to fossil aviation biofuels, on the basis of a functional unit of 1 MJ aviation fuel. The majority of the LCIA methods suggest that, in respect to midpoint impacts, macauba-based biofuel is associated with the lowest impacts and eucalyptus-based biofuel the highest; whereas at endpoint level, the results are more scattered. The LCIA methods agree that biomass conversion into aviation biofuel, H2 production, and feedstock cultivation are major contributors to life cycle HH impacts. Additionally, we provide a guideline for determining an appropriate method for assessing HH impacts.

Biobased production has been promoted as a sustainable alternative to fossil resources. However, controversies over its impact on sustainability highlight societal concerns, value tensions and uncertainties that have not been taken into account during its development. In this work, the consideration of stakeholders’ values in a biorefinery design project is investigated. Value sensitive design (VSD) is a promising approach to the design of technologies with consideration of stakeholders’ values, however, it is not directly applicable for complex systems like biorefineries. Therefore, some elements of VSD, such as the identification of relevant values and their connection to a technology’s features, are brought into biorefinery design practice. Midstream modulation (MM), an approach to promoting the consideration of societal aspects during research and development activities, is applied to promote reflection and value considerations during the design decision making. As result, it is shown that MM interventions during the design process led to new design alternatives in support of stakeholders' values, and allowed to recognize and respond to emerging value tensions within the scope of the project. In this way, the present work shows a novel approach for the technical investigation of VSD, especially for biorefineries. Also, based on this work it is argued that not only reflection, but also flexibility and openness are important for the application of VSD in the context of biorefinery design.

In general, the certified pathways for the production of sustainable aviation fuels (SAFs) are still far from being competitive with fossil kerosene, although they have the potential to reduce greenhouse gas (GHG) emissions. However, the mitigation costs related to SAFs and how they compete with the carbon credits market remain unclear. The present study addressed these issues, evaluating SAF pathways based on hydrotreatment (HEFA process) of soybean oil, palm oil, used cooking oil (UCO) and beef tallow; dehydration and oligomerization of ethanol (ATJ technology) obtained from sugarcane, lignocellulosic residues, and steel off-gases; and the thermochemical conversion of lignocellulosic residues using the Fischer–Tropsch (FT) process and hydrothermal liquefaction (HTL). Residue-based pathways had lower mitigation costs. Used cooking oil / HEFA had the lowest value (185 USD tCO_2e⁻¹), followed by the thermochemical conversion of forestry residues (234–263 USD tCO_2e⁻¹). Of the 1G pathways, SAF production from 1G sugarcane ethanol (SC-1G/ATJ) performed better (495 USD tCO_2e⁻¹) than oil-based ones. In comparison with the carbon market, the mitigation costs of SAFs are much higher than the current prices or even future ones. However, several concerns about the credibility of the emission units and their effective mitigation effects indicate that SAFs could play an important role in aviation sector goals. Considering the potential of supplying SAF and mitigating emissions, SC-1G/ATJ was suggested as a preferred alternative in the short term. Of the residue-based pathways, tallow / HEFA and FT of forestry residues are suggested as strategic alternatives.

In recent decades, academia has elaborated a wide range of technological solutions to recover water, energy, fertiliser and other products from municipal wastewater treatment plants. Drivers for this work range from low resource recovery potential and cost effectiveness, to the high energy demands and large environmental footprints of current treatment-plant designs. However, only a few technologies have been implemented and a shift from wastewater treatment plants towards water resource facilities still seems far away. This critical review aims to inform decision-makers in water management utilities about the vast technical possibilities and market supply potentials, as well as the bottlenecks, related to the design or redesign of a municipal wastewater treatment process from a resource recovery perspective. Information and data have been extracted from literature to provide a holistic overview of this growing research field. First, reviewed data is used to calculate the potential of 11 resources recoverable from municipal wastewater treatment plants to supply national resource consumption. Depending on the resource, the supply potential may vary greatly. Second, resource recovery technologies investigated in academia are reviewed comprehensively and critically. The third section of the review identifies nine non-technical bottlenecks mentioned in literature that have to be overcome to successfully implement these technologies into wastewater treatment process designs. The bottlenecks are related to economics and value chain development, environment and health, and society and policy issues. Considering market potentials, technological innovations, and addressing potential bottlenecks early in the planning and process design phase, may facilitate the design and integration of water resource facilities and contribute to more circular urban water management practices.

The growth in biofuels’ investment brings with it concerns about the social and environmental impacts of the sector. Several tools and frameworks have been used to address these concerns, including the Responsible Research and Innovation (RRI) framework. This paper analyzes whether this framework can be applied in contexts where local culture and values shape differently the freedom of speech and engagement, such as in developing countries in which biofuel innovation projects are often implemented. A literature review focused on eight case studies of other authors was used to explore the role of “participation” as a structural element of the RRI framework and the impact of its absence where effective participation in the innovation development process is not possible. In conclusion, we highlight how this inspirational normative framework, designed to influence innovation, is misused to judge its impacts. More than that, the conclusions of such misused applications reflect more the difficulties involved in applying guidelines than the responsible character of the innovation, whose impacts are usually defined upfront materially and measurably.

Municipal wastewater cannot any longer be perceived as a waste stream because it contains water, energy, fertilizer and other products that can be recovered with innovative technologies in so called ‘water resource factories’. Therefore a paradigm shift has been proclaimed to design water resource factories in the future that feed into a circular economy. The rapid development of new resource recovery technologies requires a solid analysis prior to their integration into treatment processes to understand more about their potential to contribute to more circular urban water management practices. Mass and energy balances are an excellent method to model resource recovery potentials of innovative processes at an early design stage because they allow quantifying recoverable resources as well as trade-offs between possible recovery technology choices. We modelled a real wastewater treatment plant which uses aerobic granular sludge treatment and is currently operated with no on-site resource recovery. Then, 5 different possible process designs that would recover chemical oxygen demand (COD) as energy and/or extracellular polymeric substances (EPS), and phosphorous (P) as struvite have been modelled. The integration of anaerobic digestion for subsequent electricity and heat generation from methane provides the possibility to recover on-site a rather small fraction of influent-COD as energy. But if this is combined with chemically enhanced primary treatment (CEPT), almost one third of the influent-COD may be recovered. Simultaneous energy and EPS recovery may lead to trade-offs as CEPT integration for maximum energy recovery may halve the EPS recovery potential but would increase the overall influent-COD recovery rate. Struvite fertilizer recovery integration may only recover a small fraction of influent-P and is therefore questionable when other P recovery options are possible that aim for higher recovery rates. The fertilizer recovery potential may be significantly decreased by EPS recovery since the latter contain P. This study helps to understand how aerobic granular sludge based treatment processes can be designed as water resource factories. Mass and energy balances can be conducted at a very early process design stage and results may be used to identify promising process designs for subsequent more in depth techno-economic or environmental impact assessments.