With the increase in global population leading to an ever-growing food demand, there is a need to produce foods with high nutritional value for both humans and animals. In recent years, insects have been studied as an alternative ingredient for food production in various parts of the world, presenting an alternative source of high-quality proteins with low environmental impact. In particular, the black soldier fly Hermetia illucens shows promise, as an insect with simple rearing requirements, resilience to adverse environmental conditions, and a high rate of conversion of waste material, which they turn into nutrient-rich biomass. All these qualities make it an attractive option for use in food production technologies, such as extrusion cooking. This process allows for minimal steps of preparation for production, which along with its combination of cooking and mixing, results in reduced costs, and has shown positive effects on the reduction or even elimination of pathogens while allowing the inclusion of alternative protein sources in extruded food products.
To minimize the emissions from the production of biofuels, one aim is to reduce or completely replace the amount of fossil fuels used for internal process energy. A conceivable solution is the use of volatile renewable energy sources such as solar and wind. The fluctuation of these energy sources in their production inevitably leads to a transformation to flexible power consumption, commonly referred to as demand side management (DSM). In current research, a wide range of processes has been identified to be suitable for DSM application. Although biorefineries have not yet been tested for DSM application, it is noteworthy that many of the DSM suitable processes are employed in biofuel plants. Thus, this contribution offers a comprehensive overview of DSM options drawn from literature with a special focus on process steps, which have been analysed for operational and capacity flexibility and which are found in or are transferable to biorefinery systems. By identifying process steps in biofuel production that can be operated flexibly, this extensive literature study helps to find technical restrictions limiting the overall process flexibility. The scope of this contribution is to create an overview of which processes in biofuel production can be considered for DSM use. A systematic review of options for DSM in biofuel production is presented in this contribution. Overall it can be stated that indeed many process steps in biorefineries have been identified as flexibly operable. Technical restrictions limiting the flexibility of these process steps can be derived from this review for each of these process steps. Furthermore, the relative amount of operating load or temperature variation each process step under consideration can provide was analysed from the respective papers studied.
Flexible biogas production can enable demand-oriented energy supply without the need for expensive gas storage expansions, but poses challenges to the stability of the anaerobic digestion (AD) process. In this work, biogas production of laboratory-scale AD of maize silage and sugar beets was optimized to cover the residual load of an electricity self-sufficient community using a simple process model based on first-order kinetics. Experiments show a good agreement between biogas demand, predicted, and measured biogas production. By optimizing biogas conversion schedules based on the measured gas production, a gas storage capacity of 7 to 8 hours was identified for maximum flexibility, which corresponds to typical gas storage sizes at industrial biogas plants in Germany. Various stability indicators were continuously monitored and proved resilient process conditions. These results demonstrate that demand-oriented biogas production using model predictive control is a promising approach to enable existing biogas plants to provide balancing energy.
This review paper aims to investigate the supply costs and prices for biogenic residues, wastes and by-products for Europe that are used as key economic parameters for techno-economic analyses in the relevant literature. The scope of the paper is to show: (i) which information on costs and prices is used in techno-economic models; (ii) which sources these monetary values are based on; and (iii) whether these values are able to be compared and classified. The methodology employed in this review paper is a systematic evaluation of the supply costs and prices for residual biomass used as the basis for techno-economic analyses in the literature. Three evaluation criteria (COST TYPE, TIME PERIOD and COST SCOPE) are used to operationalise the scope of the delivery, the time frame and the spatial resolution of the monetary values. The pricing and cost variables UNIT and BIOMASS are also studied. The results show that the supply costs and pricing differ in terms of the units used, the scope of the delivery and the spatial scale, making it difficult to compare individual studies or transfer the findings to other use cases. The costs and pricing examined range from 0.00 EUR/Mg (dm) for “bio-waste from private households” to a regional value of 1097.02 EUR/Mg (dm) for “woody biomass from vineyards”. They are rarely based on cost calculations or price analyses over a period of several years, and more than half of the literature sources examined do not take into account regional differences. The findings suggest that the input data on costs and prices are not always of sufficient quality. For that reason, in the future, the data on supply costs and prices that are provided for processing should have a more detailed temporal and spatial resolution.
Several energy system optimization models are used to identify solutions for the German energy transition. Most of them lack of detail in regard to the representation of the heterogeneous heat sector and the manifold bioenergy options. Benopt-Heat closes the gap and several research questions related to the future use of bioenergy in the German heat sector could be addressed. Based on the model results and novel methods to address uncertainty, policy insights with a high level of detail and confidence are generated. This software publication provides a basis to further investigate the manifold identified research questions in this field.
A “bioeconomy cluster” is an association of companies and other institutions that have set themselves the goal of producing biomass and converting it into products with added value. Bioeconomy clusters with different focuses exist throughout Europe. This chapter describes the background, composition and covered sectors of these clusters and analyses similarities, differences and trends.
The increasing demand for renewable energy sources and demand-oriented electricity provision makes anaerobic digestion (AD) one of the most promising technologies. In addition to energy crops, the use of lignocellulosic residual and waste materials from agriculture is becoming increasingly important. However, AD of such feedstocks is often associated with difficulties due to the high content of lignocellulose and its microbial persistence. In the present work, the effect of hydrothermal pretreatment (HTP) on the digestibility of wheat straw is investigated and evaluated. Under different HTP temperatures (160–180 °C) and retention times (15–45 min), a significant increase in biomethane potential (BMP) can be observed in all cases. The highest BMP (309.64 mL CH4 g−1 volatile solid (VS) is achieved after pretreatment at 160 °C for 45 min, which corresponds to an increase of 19% of untreated wheat straw. The results of a multiple linear regression model show that the solubilization of organic materials is influenced by temperature and time. Furthermore, using two different first-order kinetic models, an enhancement of AD rate during hydrolysis due to pretreatment is observed. However, the increasing intensity of pretreatment conditions is accompanied by a decreasing trend in the conversion of intermediates to methane.
Removal of carbon dioxide from the atmosphere will be required over the next decades to achieve the Paris Agreement goal of limiting global warming to well below 2°C aiming at not exceeding 1.5°C. Technological and ecosystem-based options are considered for generating negative emissions through carbon dioxide removal (CDR) and several nations have already included these in their Long-Term Low Greenhouse Gas Emission Development Strategies. However, strategies for development, implementation, and upscaling of CDR options often remain vague. Considering the scale at which CDR deployment is envisioned in emission pathways for limiting global warming to 1.5°C, significant environmental, social, and institutional implications are to be expected and need to be included in national feasibility assessments of CDR options. Following a multi-disciplinary and comprehensive approach, we created a framework that considers the environmental, technological, economic, social, institutional, and systemic implications of upscaling CDR options. We propose the framework as a tool to help guide decision-relevant feasibility assessments of CDR options, as well as identify challenges and opportunities within the national context. As such, the framework can serve as a means to inform and support decision makers and stakeholders in the iterative science-policy process of determining the role of CDR options in national strategies of achieving net-zero carbon emissions.
The integration of power-to-gas (PtG) technology into existing urban anaerobic digestion (AD) plants could be an interesting concept to recycle biogenic CO2 and increase CH4 production as renewable fuel to further decarbonize public transport buses (PTB). However, such implementation is challenging for several reasons, including power restrictions during peak load, physical and temporal availability of CO2 from AD plants, and the need for expensive intermediate gas storages to avoid mismatch between the constrained synthetic CH4 production and the variable fuel demand. To investigate whether synthetic CH4 could be a feasible alternative for buses currently powered by fossil fuels, a dynamic model was built for discrete-event simulations of PtG technology integrated into an urban AD plant designed to supply biomethane as fuel for bus fleets. Different scenarios were assessed, including variations in power availability to run a proton exchange membrane electrolyser as well as variations in the production scale of synthetic CH4 based on ex-situ biological methanation. The results show that a constrained power utilization (maximum of 12 h per day) increased the production cost of synthetic CH4 by 20%. In contrast, an increase in PtG production capacity from 0.75 MWth to 2.25 MWth decreased costs by 16%. From the PTB operators’ perspective, the total cost of ownership (TCO) increased in all analysed scenarios when replacing diesel buses by gas buses powered by synthetic CH4. However, when using synthetic CH4 as drop-in fuel to replace natural gas in existing gas bus fleets, the TCO could be reduced up to 4.4% depending on the PtG plant configuration and the assumed fossil fuel price. Furthermore, our results show that a carbon tax on fossil fuels has only a limited effect on promoting synthetic CH4 as alternative fuel for PTB, and additional incentives should be put in place to prioritize a fuel switch, especially for existing gas bus fleets.
The transformation from a fossil-based economy to a sustainable and circular bioeconomy is urgently needed to achieve the climate targets of the Paris Agreement, reduce air pollution and ensure a long-term competitive economy. Due to its carbonaceous and aromatic basic components, lignin has the potential for material valorization within bioeconomy. So far, lignin produced in the pulp and paper industry has mainly been used internally to generate thermal process energy, as it is difficult to extract it from biomass in a pure and unaltered form. The valorization of lignin to improve the economics of pulp mills is a current aim of the industry. Hydrothermal treatment (HTT) of a partial flow from the lignin stream to produce a functional filler for use in polymer blends is one valorization option. The environmental assessment of the lignin-based HTT filler, conducted using life cycle assessment (LCA), shows that substitution of the conventional fillers carbon black and silica could be associated with significant reductions in greenhouse gas emissions and air pollutants. Depending on the allocation methodology and the reference filler considered, approx. 5 kg CO2 eq./kg filler, 80–93% SO2 emissions, 27–79% PM emissions, and 88–98% PAH emissions can be saved.
The quality of silages could deteriorate during feed-out to biogas reactors. Using airtight silos where silages in pulp form can be pumped directly into a reactor may mitigate this problem. In this study, sugar beet leaves were ensiled in vertical columns and in airtight bags at ambient temperature for 370 days. Homofermentative lactic acid bacteria were added to some of the samples in the airtight bags to test the effect on silage quality and biomethane potential (BMP). Quality of ensiling and BMP were studied across the height of the columns. With the exception of the silages at the top of the columns, lactic acid represented over 55% of the concentration of total fermentation products in the silages. The silages at the bottom of the columns had a 20.9% higher BMP than the silages at the top, indicating that the BMP increases with the column depth. The BMP of the silage with additive in the airtight bags was 8% higher than that of the silage without additive. Four kinetic models were used to fit the experimental BMP, out of which the one-step two-fraction kinetic model described the experimental BMP better than other models. ARTICLE HISTORY
The reduction in greenhouse gas (GHG) emissions by shifting towards renewable energy sources to control global warming is one of the main challenges of the 21st century [...]
Solar photovoltaic (PV) is a key technology for any renewable energy system. As subsidy-free PV becomes more and more economically feasible, region-specific planning tools that define areas suitable for ground-mounted PV are needed. While many top-down studies have assessed suitable areas at a national scale, an accurate scalable bottom-up assessment of regional ground-mounted PV potentials in high spatial and temporal resolution that goes further than a mere identification of appropriate land areas is missing. This work introduces such a method based on digital landscape models that consider terrain slope, orientation, location-specific irradiation, and land use type, and combines this geoinformatical information with a PV yield model that allows to assess hourly PV generation potential on suitable areas. The method is validated with three existing ground-mounted PV plants in Germany, where a comparison of real and simulated annual electricity yields shows average deviations of 5%. Subsequently, ground-mounted PV potentials in three German counties with varying settlement structures as well as topographic and weather patterns are assessed and a comparison of yearly and hourly simulated generation potentials with regional electricity demand is performed. While the yearly analysis demonstrates the substantial overall potentials of local ground mounted-PV in all regions, with demand coverages ranging from 80% to hypothetically more than 40 times of current electricity demand according to current regulations, the hourly autarky ratio, defined as the share of hours of a year where ground-mounted PV can satisfy demand, ranges from 25% to 40%, without consideration of storage or demand side management. A subsequent investigation of the ability to export excess electricity generation from ground-mounted PV shows that the two regions with highest ground-mounted PV potentials have less-developed grid infrastructures, thus restricting excess electricity generation export potentials.
We can expect a remarkable expansion and cross-sectoral deployment of PV and wind power in the current decade. The intermittent nature of these renewables, however, will evoke challenges regarding matching energy supply and demand. Studies and strategies that aim to solve this challenge tend to neglect the flexibility potential of modern and sustainable bioenergy, despite this being the leading renewable energy resource today. We explore the current status of, and stakeholder expectations for, bioenergy flexibility, drawing on recent questionnaire data gathered in the IEA Bioenergy TCP, including some of the authors of this study, to provide a technological and deployment status review for eleven countries. We present a wide range of commercially available bioenergy technologies that can offer flexibility services. We find that sustainable biomass can be deployed for multiple services and benefits to the energy system under varying operating conditions and loads, contributing to energy security beyond the power grid. Yet, practical deployment continues to be seen as little more than a niche innovation mainly due to limited ‘landscape pressure’ and considerable challenges in translating systemic, macro-economic and societal gains into an economic profit on a business level. Considering the large variety of flexibility services, we highlight that markets and frameworks have to be designed to sufficiently reflect the qualities and limitations of the different commodities or services. Therefore, we advocate for a heterodox energy economic debate to help settle fundamental questions about the effectiveness of different market designs based on empirical approaches, quantitative modelling, and basic analytical research.
The use of sustainable biofuels in the aviation sector with correspondingly high reduction in specific GHG emissions will make an important contribution to reducing GHG emissions from air traffic. It is expected that airports in Europe will be supplied with JET A-1 blends that also contain various types of sustainable aviation fuels (SAF) in variable proportions (“multiblend”). This article presents the results of a study assessing the environmental impact of various sustainable aviation fuels (SAF) and multiblends, including all relevant parts of their value chains, starting from SAF production to mixing of different SAF with conventional JET A-1 and finally the use of the produced multiblend. The results of the life cycle assessment indicated that the production of some SAF caused less GHG emissions than others due to the use of waste or residues as SAF feedstock or the use of by-products to meet the internal process energy demand. A detailed assessment of GHG emissions of the studied multiblend JET A-1 showed a reduction in greenhouse gas emissions of up to 35 % compared to fossil JET A-1.
Biogas, with its high carbon dioxide content (30–50 vol%), is an attractive feed for catalytic methanation with green hydrogen, and is suitable for establishing a closed carbon cycle with methane as energy carrier. The most important questions for direct biogas methanation are how the high methane content influences the methanation reaction and overall efficiency on one hand, and to what extent the methanation catalysts can be made more resistant to various sulfur-containing compounds in biogas on the other hand. Ni-based catalysts are the most favored for economic reasons. The interplay of active compounds, supports, and promoters is discussed regarding the potential for improving sulfur resistance. Several strategies are addressed and experimental studies are evaluated, to identify catalysts which might be suitable for these challenges. As several catalyst functionalities must be combined, materials with two active metals and binary oxide support seem to be the best approach to technically applicable solutions. The high methane content in biogas appears to have a measurable impact on equilibrium and therefore CO2 conversion. Depending on the initial CH4/CO2 ratio, this might lead to a product with higher methane content, and, after work-up, to a drop in-option for existing natural gas grids.
Research on additives that improve the quality of silages for an enhanced and sustainable biogas production are limited in the literature. Frequently used additives such as lactic acid bacteria enhance the quality of silages but have no significant effect on biogas yield. This study investigated the effect of a new enzymatic additive on the quality of ensiling and BMP of sugar beet leaves. Sugar beet leaves were ensiled with and without the additive (Aspergillus- and Neurospora-based additive) in ratios of 50:1 (A50:1), 150:1 (B150:1), and 500:1 (C500:1) (gsubstrate/gadditive) for 370 days at ambient temperature. Results showed that silages with additive had lower yeast activity and increased biodegradability compared to silages without additive (control). The additive increased the BMP by 45.35%, 24.23%, and 21.69% in silages A50:1, B150:1, and C500:1 respectively, compared to silages without additive (control). Although the novel enzyme is in its early stage, the results indicate that it has a potential for practical application at an additive to substrate ratio (g/g) of 1:50. The use of sugar beet leaves and the novel enzyme for biogas production forms part of the circular economy since it involves the use of wastes for clean energy production.
A future bioeconomy pursues the transformation of the resource base from fossil to renewable materials in an effort to develop a holistic, sustainable production and provision system. While the significance of this change in the German context is not yet entirely explored, scenarios analysing possible pathways could support the understanding of these changes and their systemic implications. Bioeconomy in detail depends on respective framework conditions, such as the availability of biomass or technological research priorities. Thus, for scenario creation, transferable methods for flexible input settings are needed. Addressing this issue, the study identifies relevant bioeconomy scenario drivers. With the theoretical approach of narrative analysis, 92 statements of the German National Bioeconomy Strategy 2020 have been evaluated and 21 international studies in a STEEPLE framework were assessed. For a future German bioeconomy 19 important drivers could be determined and specific aspects of the resource base, production processes and products as well as overarching issues were exploratively characterised on a quantitative and qualitative basis. The developed method demonstrate an approach for a transparent scenario driver identification that is applicable to other strategy papers. The results illustrate a possible future German bioeconomy that is resource- and technology-driven by following a value-based objective, and which is supplied by biogenic residue and side product feedstocks. As such, the bioeconomy scenario drivers can be used as a starting point for future research like scenario development or modelling of a future German bioeconomy.
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