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Die Metropolregion Santiago (MRS) verzeichnete in den letzten Jahren ein großes Bevölkerungswachstum und einen Anstieg des Lebensstandards. Als Folge davon hat sich das Aufkommen von Siedlungsabfällen fast innerhalb von 10 Jahren verdoppelt. Die Daten für den aktuellen Zustand des Abfallmanagements wurden durch Feldforschungen, Fragebögen, Feldbesuche und durch eine systematische Auswertung von bereits vorliegender Literatur erhoben. Das integrative Nachhaltigkeitskonzept der Helmholtz-Gemeinschaft diente als konzeptioneller Rahmen für die Studie. Zur Bewertung des aktuellen Zustands des Abfallmanagements wurden Nachhaltigkeitsindikatoren identifiziert, deren aktuelle Werte bestimmt und Zielwerte festgelegt. Die Nachhaltigkeitsanalyse zeigt, dass die größten Defizite darin liegen, dass nahezu die gesamte Abfallmenge ohne jegliche Vorbehandlung deponiert wird. Damit verbunden sind lang andauernde Emissionen von Treibhausgasen. Um herauszufinden, wie der informelle Sektor im Abfallmanagement zur Nachhaltigkeit beiträgt, wurden veröffentlichten Erfahrungen mit informellen Müllsammlern in Lateinamerika analysiert. Dabei wurden die entsprechenden Akteure sowie etablierte Allianzen zwischen diesen Akteuren identifiziert. Schlüsselfaktoren für ein nachhaltiges Abfallmanagement unter Einbeziehung des informellen Sektors sind die Legalisierung der Schattenwirtschaft und feste Verträge mit Partnerunternehmen. Relevante Akteure für die Gestaltung der Arbeitsbedingungen des informellen Sektors sind Vertreter privater und öffentlicher Unternehmen, einzelne gesellschaftliche Gruppen sowie Vertreter von Nichtregierungsorganisationen. Schließlich wurden drei explorative Szenarien für das Bezugsjahr 2030 entwickelt: Business as Usual (BAU), Collective Responsibility (CR) und Market Individualism (MI). Das BAU-Szenario enthält eine getrennte Sammlung von Bioabfall und von Wertstoffen; hervorgerufen durch einen verstärkten Organisationsgrad der informellen Müllsammler und den Ausbau von Bring-Systemen. Die Errichtung mechanischer Sortierungsanlagen trägt zur Verwertung der Materialien und zum Recycling bei. Das entstehende Deponiegas und Biogas wird als erneuerbare Energiequelle genutzt. Das CR-Szenario enthält eine getrennte Sammlung von Bioabfall und Wertstoffen. Dies wird erreicht durch eine verstärkte Zusammenarbeit mit den jetzt organisierten Müllsammlern und durch den Ausbau von Bring-Systemen. Mechanische Sortierungsanlagen tragen zur Verwertung von Materialien und zum Recycling bei. Durch Abtrennung einer heizwertreichen Fraktion in mechanisch biologischen Anlagen werden Sekundärbrennstoffe produziert. Darüber hinaus werden, das entstehende Deponiegas sowie das in Vergärungsanlagen erzeugte Biogas energetisch genutzt. Im MI-Szenario sind Wiederverwertungsstrategien von untergeordneter Bedeutung. Es gibt kein Interesse an einer Zusammenarbeit mit den informellen Müllsammlern und keine Anreize für einen verstärkten Organisationsgrad in diesem Bereich. Deshalb bleibt die Branche weitgehend informell. Technologische Entwicklungen in diesem Szenario enthalten die mechanische Sortierung von gemischtem Abfall und die energetische Verwertung von Deponiegas. Die Ergebnisse zeigten, dass das Pro-Kopf-Aufkommen an Siedlungsabfällen im Jahr 2030 in allen Szenarien deutlich höher als im Jahr 2007 ist und der festgelegte Zielwert von 1,6 kg/Kopf/Tag nicht erreicht wurde. Den höchsten Wert (2,0 kg/Kopf/Tag) weist das MI-Szenario auf, der niedrigste Wert (1,8 kg/Kopf/Tag) wurde im CR-Szenario gefunden. Eine Vorbehandlung der gesammelten gemischten Siedlungsabfälle findet nur im CR-Szenario statt, der entsprechende Wert beträgt 18 %, der Zielwert wird damit nicht erreicht. Die höchsten Treibhausgasemissionen treten im MI-Szenario (295 kg CO2-eq/Kopf/Jahr) auf, den niedrigsten Wert (155 kg CO2-eq/Kopf/Jahr) findet man im CR-Szenario. All diese Werte sind, verglichen mit dem festgelegten Zielwert von 71 kg/Kopf/Jahr, deutlich zu hoch. Der Zielwert für die Wiederverwertungsquote wurde im CR-Szenario erreicht (43 %), den niedrigsten Wert zeigt das MI-Szenario (20 %). Die Zielwerte für das Einkommen der Müllsammler wurden im CR-Szenario erreicht (128 %). Im MI-Szenario beträgt dieser Wert lediglich 51 %. Die Kosten für das Abfallmanagement im Verhältnis zum Bruttoinlandsprodukt sinken in den drei Szenarien. Aus den Ergebnissen lässt sich ableiten, dass ein Einbeziehen von mehreren Faktoren erforderlich ist, um die Nachhaltigkeit des Abfallmanagementsystems in den drei Szenarien zu steigern und dass es von wesentlicher Bedeutung ist, schon vorhandene und gut funktionierende Subsysteme, wie das der informellen Müllsammler, zu nutzen und zu stärken. Ebenso ist die Umsetzung robuster Behandlungstechnologien, die einen Beitrag zur Reduktion negativer Umweltauswirkungen leisten, zu forcieren. Diese Technologien sollten preiswert sein, um ihren Einsatz auch unter wirtschaftlich vertretbaren Gesichtspunkten zu ermöglichen. The Metropolitan Region of Santiago (MRS) has experienced a large growth in population in recent years and a rise in the standard of living. Therefore, its municipal solid waste (MSW) has almost doubled in 10 years. Data about the current situation of MSW management in MRS were collected during field research, interviews, field visits and by a systematic evaluation of existing documentary literature. The Integrative Sustainability Concept of the Helmholtz Association provided a conceptual framework for the study. The sustainability analysis showed that the largest deficits are in the current amount of MSW deposited at sanitary landfills without any pre-treatment, and the emission values of greenhouse gases associated with waste treatment and final disposal. To find out if and how the informal waste sector contributes to sustainability, experiences of organization of informal primary collectors in Latin America were analyzed. The key factors which have an influence on their working conditions were identified. These factors include the existence of a legal framework for the informal waste sector; the existence of alliances with production companies guaranteeing a reliable industrial market for secondary raw materials and expansion of activities beyond collection of recyclables. Key stakeholders included people from the public and the private sector, from the civil society and from NGOs. Three explorative scenarios were developed for the year 2030: Business as Usual (BAU), Collective Responsibility (CR), and Market Individualism (MI). Waste generation, waste composition and different practices of waste collection, recovery and treatment were taken into account for the scenarios formulation. The BAU scenario incorporated separate collection of biowaste, recyclable materials with some participation of organized primary collectors and an expansion of drop-off systems. The mechanical sorting of mixed waste was introduced. The utilization of landfill gas as an energy source was promoted and the production of biogas in anaerobic digestion plants was implemented. The CR scenario incorporated separate collection of biowaste, commitment to work together with the primary waste collectors and an expansion of drop-off systems. The mechanical and mechanical biological treatment of mixed waste was introduced. The utilization of landfill gas as an energy source is promoted and the production of biogas in anaerobic digestion plants was implemented. In the MI separate collection of biowaste and recyclable materials was irrelevant. An organization of the informal primary collectors did not take place. Mechanical sorting of mixed waste was introduced. Utilization of landfill gas as an energy source was promoted. The results showed that the generation flux of MSW is at least 50% larger in all scenarios in 2030 compared to the year 2007, exceeding the limit value proposed. The highest value (2.0 kg/(person•day) is obtained in the MI scenario, and the lowest (1.8 kg/(person•day)) in the CR scenario. Pre-treatment of mixed MSW collected is only achieved in the CR scenario with a value of 18%, however, the target value is not achieved. The highest greenhouse gas emission value is obtained in the MI scenario with 295 kg CO2eq/(person•year), the lowest value of 155 kg CO2-eq/(person•year) is obtained in the CR scenario; a value that is still very high in comparison with the suggested target. The largest recycling rate is obtained in the CR scenario (43%), which is better than the target value proposed, the lowest recycling rate is obtained in the MI scenario (20%). The income of primary collectors in comparison with the income of one individual household is improved significantly in the CR scenario (128%), in the MI scenario, earnings of primary collectors decreased to 51%. The share of GDP spent on MSW management is lower in 2030, compared to the year 2007, in all scenarios the largest value of 0.17% is obtained in the CR scenario, and the lowest value of 0.14% is obtained in the MI scenario. The results of the evaluation of the scenarios showed that the largest sustainability deficits are the amount of mixed MSW which undergoes pre-treatment, the greenhouse gas emissions associated to MSW treatment and disposal, as well as the share of GDP spent on MSW management. The results obtained suggested that an integration of several factors is required to increase sustainability. It is essential to strengthen and take advantage of the subsystems which are working within the waste management system, as in the case of the informal sector. In addition to the implementation of flexible treatment technologies which help to decrease negative environmental impacts. Moreover, the costs of these technologies should be affordable, allowing a better financial management.

The project between tthe Deutsche Biomasseforschungszentrum (DBFZ) and the Karlsruhe Institute of Technology (KIT) focuses on the pr rovision of alternative fuels by thermochemical conversion. Biogenic residues and wastes which are not used yet or which could be utilised more efficiently are studied. The selection of possible feedstock was supported by a techhnical potential analysis including the competition to th he food industry. The technical suitability of raw materials for the fast pyrolysis (FP) process was of special in nterest. As a possible feedstock following types of biomass were studied: corn stover, corn cobs, biogenic floating re efuse (river Rhine and Baltic Sea), scrap wood, bark, rape s straw, sunflower straw, draff, diverse residues of flour production and hay. A process development unit (PDU) with a biomass feeding rate of 10 kg/h and a twin screw m mixer reactor was used for all experiments. It was found that different types of biomass form different char, condensate e and gas yields due to varying ash levels and lignocellulosic composition. Elemental formulas for feedstock, char, organic condensate and gas were estimated independent on t the feedstock due to similar elemental compositions. Pyrolysis gas analysis during the experiments gave information on the mass yields. A CO/CO2-ratio of 1 (i.e. wood) corresponds to organic condensate yields of about 50 wt.-%%, whereas a ratio of 0.3-0.7 (straw) corresponds to 18-32 wt. .-% respectively. Proceedings of the 20th European Biomass Conference and Exhibition, 18-22 June 2012, Milan, Italy, pp. 973-977

With energy modeling at different complexity levels for smart cities and the concurrent data availability revolution from connected devices, a steady surge in demand for spatial knowledge has been observed in the energy sector. This transformation occurs in population centers focused on efficient energy use and quality of life. Energy-related services play an essential role in this mix, as they facilitate or interact with all other city services. This trend is primarily driven by the current age of the Ger.: Energiewende or energy transition, a worldwide push towards renewable energy sources, increased energy use efficiency, and local energy production that requires precise estimates of local energy demand and production. This shift in the energy market occurs as the world becomes aware of human-induced climate change, to which the building stock has a significant contribution (40% in the European Union). At the current rate of refurbishment and building replacement, of the buildings existing in 2050 in the European Union, 75% would not be classified as energy-efficient. That means that substantial structural change in the built environment and the energy chain is required to achieve EU-wide goals concerning environmental and energy policy. These objectives provide strong motivation for this thesis work and are generally made possible by energy monitoring and modeling activities that estimate the urban energy needs and quantify the impact of refurbishment measures. To this end, a modeling library called aEneAs was developed in the scope of this thesis that can perform city-wide building energy modeling. The library performs its tasks at the level of a single building and was a first in its field, using standardized spatial energy data structures that allow for portability from one city to another. For data input, extensive use was made of digital twins provided from CAD, BIM, GIS, architectural models, and a plethora of energy data sources. The library first quantifies primary thermal energy demand and then the impact of refurbishment measures. Lastly, it estimates the potential of renewable energy production from solar radiation. aEneAs also includes network modeling components that consider energy distribution in the given context, showing a path toward data modeling and simulation required for distributed energy production at the neighborhood and district level. In order to validate modeling activities in solar radiation and green façade and roof installations, six spatial models were coupled with sensor installations. These digital twins are included in three experiments that highlight this monitoring side of the energy chain and portray energy-related use cases that utilize the spatially enabled web services SOS-SES-WNS, SensorThingsAPI, and FIWARE. To this author's knowledge, this is the first work that surveys the capabilities of these three solutions in a unifying context, each having its specific design mindset. The modeling and monitoring activity and their corresponding literature review indicated gaps in scientific knowledge concerning data science in urban energy modeling. First, a lack of standardization regarding the spatial scales at which data is stored and used in urban energy modeling was observed. In order to identify the appropriate spatial levels for modeling and data aggregation, scale is explored in-depth in the given context and defined as a byproduct of resolution and extent, with ranges provided for both parameters. To that end, a survey of the encountered spatial scales and actors in six different geographical and cultural settings was performed. The information from this survey was used to put forth a standardized spatial scales definition and create a scale-dependent ontology for use in urban energy modeling. The ontology also provides spatially enabled persistent identifiers that resolve issues encountered with object relationships in modeling for inheritance, dependency, and association. The same survey also reveals two significant issues with data in urban energy modeling. These are data consistency across spatial scales and urban fabric contiguity. The impact of these issues and different solutions such as data generalization are explored in the thesis. Further advancement of scientific knowledge is provided specifically with spatial standards and spatial data infrastructure in urban energy modeling. A review of use cases in the urban energy chain and a taxonomy of the standards were carried out. These provide fundamental input for another piece of this thesis: inclusive software architecture methods that promote data integration and allow for external connectivity to modern and legacy systems. In order to reduce time-costly extraction, transformation, and load processes, databases and web services to ferry data to and from separate data sources were used. As a result, the spatial models become central linking elements of the different types of energy-related data in a novel perspective that differs from the traditional one, where spatial data tends to be non-interoperable / not linked with other data types. These distinct data fusion approaches provide flexibility in an energy chain environment with inconsistent data structures and software. Furthermore, the knowledge gathered from the experiments presented in this thesis is provided as a synopsis of good practices.

Presentation at the 242nd ECS Meeting, October 9-13, 2022, Atlanta, GA (USA).

Bio-oil composition can differ depending on the biomass feedstock. Such information is essential if upgrading to a liquid fuel or to platform chemicals is intended. Furthermore, water and inorganic elements have to be taken into account for the catalyst selection. In this work, two bio-oils from wheat straw and beech wood were characterized by different techniques. Both were composed by a light and a heavy phase separately analyzed. The water content of the fractions differed over a wide range between 14.4 and 56.7 wt.% and therefore also the HHV (between 28.5 and 9.2 MJ/Kg). Both phases showed very low content of sulfur (<0.4 wt.%), which can have influence the lifetime of the catalyst. The 1H-NMR integration showed higher values in the regions of alkanes, carboxylic acid or keto-groups, and hetero-(aromatics) for both heavy phases, while light phases showed higher values in the water, O-H exchanging and carbohydrates region. So the heavy phases seem to be a good basis if phenols and its derivatives are expected and the light phases if alcohols are of interest. These results show that the bio-oils composition is essential for upgrading reactions, impacting on the products as well as on the choice of the catalyst. Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 1143-1147

Chile is known for a strong forest industry based on 2.5 million ha of forest plantations. The harvest and processing of 44 million m3 of roundwood leads to a biomass potential of more than 5 million tons of plantation and sawmill residues per year which could be utilized to produce wood pellets. However, Chilean pellet mills face a limited domestic demand of approximately 100,000 tons per year. As 60% of the Chilean pulp and wood chips are shipped to diverse destinations in Asia and Europe, the export of wood pellets could offer an opportunity to utilize the potential of residual biomass. In this study, an economic assessment of the production and export of Chilean pellets is carried out. A simulation model is developed which covers the entire supply chain including pellet production, transportation and storage, port operations and maritime shipping. The model is applied to compare regular and torrefied pellets and different destination ports in Europe and Asia. The results indicate that torrefied pellets would be competitive with regular wood pellets in the considered target markets. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 1279-1288

Motivated by the population growth, climate change and limited fossil fuel resources, renewable alternatives for fuels and chemicals production are becoming more and more important. Biomass, especially residual lignocellulosic biomass shows a significant potential as feedstock for bioenergy, due to its high carbon content and short-term availability. Among the thermochemical conversion technologies, fast pyrolysis for biomass liquefaction can be considered already well stablished, as several commercial plants are spread worldwide. However, fast pyrolysis bio-oil, the main product of fast pyrolysis, currently shows limited bioenergy application as boiler fuel for heat production. It can be explained by its chemical composition and properties, as fast pyrolysis bio-oil is an acidic multi-component product, with low energetic density due to its high content of water and oxygenated compounds. Moreover, wood is the only feedstock currently used commercially. In order to expand the feedstock range and application viability, an additional upgrading treatment may be required in order to improve the fast pyrolysis properties, meeting existing fuel standards. In order to do so, catalytic hydrotreatment is considered a promising upgrading treatment, as it is a well-known technology currently applied in petroleum refineries for heteroatoms removal from crude oil. However, due to the differences in chemical composition, the hydrotreatment conditions applied to crude oil cannot be simply applied to fast pyrolysis bio oil. Although research in this field has been carried out for a few decades, there are still open questions to enable hydrotreatment to produce fuel oils from residual biomass in stable processes. By developing a robust fast pyrolysis bio-oil hydrotreatment process, small biorefineries units could be installed near to feedstock sourcing or even be installed in biorefinery units already stablished, such as a sugarcane biorefinery, in which high volumes of residual biomass are generated. Also, co-processing of crude oil and fast pyrolysis bio-oil in petroleum refineries may be a feasible option. In view of the importance of the hydrotreatment for expansion of the range of chemicals obtained by thermochemical conversion of residual biomass, the presented work investigated the hydrotreatment of fast pyrolysis bio-oil applying nickel-based catalysts. In a systematic evaluation nickel-based catalysts with different metal loading, supports and promoters have been studied. Overall, six nickel-based catalyst were screened and compared to ruthenium supported in activated carbon. The hydrotreatment conditions in terms of reaction time, temperature and pressure were optimized and fast pyrolysis bio-oils derived from beech wood and residual biomass (sugarcane bagasse) were hydrotreated. Additionally, the heavy phase separated from beech wood bio-oil, characterized by its high content of lignin-derived compounds, was hydrotreated. The effect of deactivation by sulphur on the hydrotreatment was investigated by use of model substances in a continuously operated trickle bed reactor, since with this reactor the deactivation can be observed depending on time (in contrast to batch experiments). Finally, a 2 step upgrading approach of a previously upgraded fast pyrolysis bio-oil was proposed and verified. Initially two high loaded nickel-based catalysts (monometallic nickel and nickel chromium) were evaluated in comparison to Ru/C by batch hydrotreatment of beech wood bio-oil at 80 bar, 4 h, 175 °C and 225 °C. Both nickel-based catalysts revealed similar hydrodeoxygenation activities for the conditions applied and the nickel catalysts showed the higher hydrogenation activity compared to Ru/C. The nickel-chromium catalyst demonstrated the highest activity for conversion of organic acids, ketones and sugars, attributed to the strength of the acid sites promoted by chromium oxide. When applied in a second hydrotreatment step of a previously upgraded oil, the oxygen content of the oil was reduced by 64.8 % in comparison to the original feedstock while the water concentration was reduced by 90 %. Nearly 96 % of the organic acids were converted and the higher heating value was increased by 90.1 %. Despite nickel-chromium demonstrated the best activity in the one step hydrotreatment reactions and contributed significantly in the 2-step upgrading, the oxygen content of 25.3 wt.% dry basis in the upgraded oil was still considered high. Thus, the upgrading conditions were further optimized, aiming to achieve higher hydrodeoxygenation performance. The conditions of batch hydrotreatment were optimized with nickel-chromium catalyst considering two pressures (80 and 100 bar), four temperatures (175 °C, 225 °C, 275 °C and 325 °C), for both the complete beech wood fast pyrolysis bio-oil, as well as for the heavy phase after spontaneous separation induced by intentional ageing of the bio-oil. At higher temperatures, increased hydrodeoxygenation levels were reached, while at higher pressure larger hydrogen consumption was observed with no significant influence on hydrodeoxygenation. The best conditions among all tested was obtained by hydrotreating the beech wood bio-oil at 325 °C and 80 bar; in this case, 43 % of hydrodeoxygenation was reached. Although improved hydrodeoxygenation activity observed with nickel-chromium at optimized conditions, the results motivated the synthesis and evaluation of new nickel-based catalysts, targeting higher deoxygenation levels. In the next part of this study, four nickel-based catalyst were synthesized by wet impregnation and evaluated for the hydrotreatment of beech wood fast pyrolysis bio-oil. The catalysts were supported in silica and zirconia and the influence of copper as promoter was studied. Among them, nickel-silica was the most active for hydrodeoxygenation, reducing the oxygen content of the upgraded beech wood fast pyrolysis bio-oil by more than 50 %. The highest degree of water removal as well as low gas and char production were also considered good properties attributed to this catalyst. The investigation on repeated cycles of hydrotreatment with the same catalyst showed a remaining activity even after the fourth reuse, in which 43 % of oxygen was removed. Thus, based on the results obtained with Ni/SiO2, this catalyst was selected together with nickel-chromium catalyst to be used for hydrotreatment of fast pyrolysis bio-oil from residual biomass, as until this point the study had considered only wood-based fast pyrolysis bio oil. Based on the studies so far, the integration of hydrotreatment into a thermochemical conversion route of residues in a sugarcane refinery was proposed. For that, the study encompassed sugarcane bagasse characterization, fast pyrolysis and hydrotreatment of the so derived bio-oils with nickel-chromium and nickel-silica catalyst. The detailed investigation of the bagasse and the fast pyrolysis bio-oil compositions allowed the correlation of the biomass building blocks with the monomers obtained. The hydrotreatment showed that nickel-chromium showed highest activity for organic acids conversion, as previously observed with beech wood bio-oil, whereas nickel-silica revealed more active for conversion of aromatics. Hydrodeoxygenation of 43.3 % was obtained with nickel-silica. Although both catalysts demonstrated to be active at the conditions evaluated, the high viscosities of the upgraded oils in comparison to those obtained from fast pyrolysis showed that polymerization took place and must be further investigated in detail, as it is one of the limiting factors for further application of fast pyrolysis bio-oil hydrotreatment. Overall, this studied showed to be very promising and future studies are planned. In the final part of the thesis, both high loaded nickel-based catalysts studied in the first chapters were selected for a detailed investigation in a continuous operated tricked bed hydrotreatment reactor, due to the similar nickel concentration, nickel particle size and support. The selection of both catalysts aimed to investigate the influence of sulfur on long term catalyst deactivation and the role of chromium in catalyst deactivation. Both catalysts were active for conversion of model substances over more than 48 h of reaction time. By the presence of sulfur, the selectivity of both catalysts changed, mainly towards alkene formation, while the activity remained in the same range. Formation of Ni3S2 was observed for both catalysts, but the highest intensity in the diffraction peak of metallic nickel in the nickel-chromium catalyst might be an indication of higher resistance to sulfur poisoning in comparison to Ni catalyst. In general, the catalysts were active for the conditions tested, although the hydrogenation activity was compromised by sulfur poisoning. Overall, all the catalysts tested in this study were active for hydrotreatment of fast pyrolysis bio-oils. If only stabilization of reactive compounds such as aldehydes and furfurals is required, all of them could be considered suitable candidates. In terms of hydrodeoxygenation activity, Ni/SiO2 showed the highest performance, while nickel-chromium showed to be the most active for conversion of organic acids and superior hydrogenation capacity than Ni/SiO2.

The purpose of Karlsruhe’s bioliq®-project is the conversion of biomass into synthetic chemicals and fuels (also referred to as BtL, biomass to liquids). The lignocellulosic biomass is first liquefied by fast pyrolysis in distributed regional plants to produce an energy-dense intermediate composed of pyrolysis condensates and solid char powder. Both products are mixed to a suspension (the so called bio-slurry or Syncrude) to be suitable for long storage periods and economic transport over long distances. Afterwards, in a large scale industrial facility, the biosyncrude is converted into syngas through entrained flow gasifier and then by catalysis to synfuels or platform chemicals. Regarding to a minimum of energy consumption for avoiding solid sediments in the biosyncrude, two possibilities are being taken into account: either the bio-slurry is continuously slowly stirred, or sedimentation is prevented by short-time stirring followed by an as-long-as-possible resting interval. For the investigated bio-slurries, the experimental results indicates, that it’s more efficient to stir the slurry batch-wise. Proceedings of the 22nd European Biomass Conference and Exhibition, 23-26 June 2014, Hamburg, Germany, pp. 1151-1154