• Energy Research

The handling of multi-output systems presents a crucial aspect of greenhouse gas (GHG) emission calculation as well as the certification of biofuels, and finding a robust and applicable method that accounts for distinctive characteristics of and benefits generated by all products is a challenge. In this work, GHG emission savings of 11 biofuel production concepts are assessed and the implications of methodological assumptions are discussed by applying the methodology defined by the Renewable Energy Directive (RED), allocation based on physical parameters, two hybrid approaches, as well as six variants of substitution. GHG emission savings according to RED methodology range from 35 to 57 %. Sugar beet-based ethanol shows highest savings. Results reveal that GHG savings according to the RED methodology present, in sum, a relatively good approximation of emission savings occurring due to substitution effects under given assumptions. An introduction of credits for products that are barely or not considered by the RED methodology due to allocation based on the lower heating value (LHV), i.e. fertilizers and wet feed co-products, reduces the difference between RED results and results based on substitution. If displacement mechanisms are considered by substitution, sugar beet-based ethanol, ethanol production by wet milling of wheat and sunflower biodiesel result in highest emission savings under given assumptions if oil that needs to be supplied due to occurring displacement mechanisms stems from rapeseed. The implementation of a method that supports concepts with high emission saving potential, e.g. allocation based the lower heating value of dry material, could promote emission reductions from biofuel provision.

Abstract In the upcoming decade, biofuels made from agricultural residues, wastes and by-products will most likely present an integral part of biofuel provision to achieve greenhouse gas (GHG) reduction targets. This study provides an evaluation of potential changes in GHG emissions arising from the introduction of alternative fuels. To this end, potential changes in GHG emissions arising from the introduction of 36 biorefinery configurations in 26 EU member states providing a broad spectrum of products (e.g. biofuels, chemicals, feed and food additives) are assessed. Additional electrofuel production using biogenic CO2 is evaluated. The assessment considers country specific energy supply, market conditions and soil characteristics. The potential changes in GHG emissions arising from the introduction of these facilities range from −206 to 135 and from −221 to −17 g CO2 per MJ of bioethanol provided from wheat grains and wheat straw, respectively. The analysis reveals a high variability in GHG intensities related to marginal feedstock and energy supply as well as potentially occurring displacement effects depending on location. A Monte Carlo simulation confirms potential reductions in GHG emissions. Furthermore, the analysis shows that the methodology used within the EU to evaluate GHG emissions provided by the Renewable Energy Directive (II) denies market access to certain types of biorefineries and production modalities that bear the potential to reduce GHG emissions. It is concluded that EU biofuel policy strategies targeting (advanced) biofuels should consider local conditions and markets and should especially pay attention to potential changes in other markets.

AbstractThe shift from straw incorporation to biofuel production entails emissions from production, changes in soil organic carbon (SOC) and through the provision of (co‐)products and entailed displacement effects. This paper analyses changes in greenhouse gas (GHG) emissions arising from the shift from straw incorporation to biomethane and bioethanol production. The biomethane concept comprises comminution, anaerobic digestion and amine washing. It additionally provides an organic fertilizer. Bioethanol production comprises energetic use of lignin, steam explosion, enzymatic hydrolysis and co‐fermentation. Additionally, feed is provided. A detailed consequential GHG balance with in‐depth focus on the time dependency of emissions is conducted: (a) the change in the atmospheric load of emissions arising from the change in the temporal occurrence of emissions comparing two steady states (before the shift and once a new steady state has established); and (b) the annual change in overall emissions over time starting from the shift are assessed. The shift from straw incorporation to biomethane production results in net changes in GHG emissions of (a) −979 (−436 to −1,654) and (b) −955 (−220 to −1,623) kg CO2‐eq. per tdry matter straw converted to biomethane (minimum and maximum). The shift to bioethanol production results in net changes of (a) −409 (−107 to −610) and (b) −361 (57 to −603) kg CO2‐eq. per tdry matter straw converted to bioethanol. If the atmospheric load of emissions arising from different timing of emissions is neglected in case (a), the change in GHG emissions differs by up to 54%. Case (b) reveals carbon payback times of 0 (0–49) and 19 (1–100) years in case of biomethane and bioethanol production, respectively. These results demonstrate that the detailed inclusion of temporal aspects into GHG balances is required to get a comprehensive understanding of changes in GHG emissions induced by the introduction of advanced biofuels from agricultural residues.

Die RUVIVAL-Publikationsreihe ist eine Zusammenstellung von Literaturübersichten zu Themen, die sich mit der Revitalisierung ländlicher Gebiete befassen und ist ein Teil des E-Learning-Projekts RUVIVAL. Jeder der drei Beiträge in dieser Publikation ist mit weiteren interaktiven Lerninhalten verbunden, die unter www.hoou.de einzusehen sind. Die erste Literaturübersicht befasst sich mit dem Energiezugang bei einer nachhaltigen ländlichen Entwicklung, wobei der Schwerpunkt auf dezentraler erneuerbarer Energie für die Elektrifizierung ländlicher Regionen Afrikas liegt. Der Zugang zu Elektrizität ist ein zentraler Faktor für die Verbesserung des Lebensstandards und der kommunalen Dienstleistungen wie Gesundheitsversorgung und Bildung, für die Verringerung der Armut und die Verbesserung der Geschlechtergerechtigkeit. Im Jahr 2016 lebten jedoch immer noch 14 % der Weltbevölkerung ohne Strom, meist in ländlichen Gebieten wirtschaftlich benachteiligter Regionen. Off-Grid- und Mini-Grid-Systeme werden unter dem Begriff "verteilte Energiesysteme" oder "dezentralisierte Energiesysteme" zusammengefasst und stellen eine schnelle und kosteneffiziente Methode für die ländliche Elektrifizierung dar. Zu den angewandten Technologien gehören Solar-Photovoltaik, Windkraft, kleine Wasserkraft-Anlagen und aus Restbiomasse gewonnene Energie. Diese kleineren erneuerbaren Energiesysteme bieten eine erhebliche Reduzierung der Verbrennung fossiler Brennstoffe und der damit verbundenen Emission von Treibhausgasen. Dieser Beitrag untersucht erneuerbare Energiesysteme und konzentriert sich auf Energiedienstleistungen für die Stromerzeugung in den ländlichen Gebieten Afrikas. Die zweite Literaturübersicht befasst sich mit der integrierten dezentralen Abwasseraufbereitung für ländliche Gegenden, wobei der Schwerpunkt auf der Rückgewinnung von Ressourcen liegt. Die am besten geeignete und nachhaltigste Lösung für das Abwassermanagement in jedem Umfeld ist diejenige, die wirtschaftlich, ökologisch und technisch vernünftig umsetzbar sowie für die jeweilige Gemeinschaft gesellschaftlich akzeptabel ist. Zentralisierte Abwassersammel- und -behandlungssysteme erweisen sich als ressourcenintensiv und komplex, insbesondere in Regionen mit geringer Bevölkerungsdichte und vereinzelt liegenden Haushalten. Alternativ erscheint der Ansatz der dezentralisierten Abwasserbehandlung als eine nachhaltige und logische Lösung, um Probleme im Zusammenhang mit der ländlichen Abwasserwirtschaft anzugehen. Diese Publikation gibt einen Überblick sowohl über die Vorteile, als auch die Grenzen verschiedener zentralisierter und dezentralisierter Ansätze zur Abwasseraufbereitung und -verwaltung. Vorgestellt wird eine nachhaltige Lösung für das Abwassermanagement in ländlichen Gegenden, die auf dem Konzept der ökologischen Abwasserentsorgung mit Schwerpunkt auf der Rückgewinnung von Wasser und Nährstoffen basiert. RUVIVAL Publication Series is a compilation of literature reviews on topics concerned with the revitalisation of rural areas. RUVIVAL Publication Series is part of the e-learning project RUVIVAL and each of the two contributions in this publication is connected to further interactive multimedia material, which can be reached under www.hoou.de. The first literature review is concerned with energy access for sustainable rural development, with a focus on distributed renewable energy for rural electrification in Africa. Access to electricity is a key mechanism for the improvement of living standards and community services such as healthcare and education, for the reduction of poverty and enhancement of gender justice. However, in 2016, 14 % of the world’s population still lived without electricity, mostly located in rural areas of economically poor areas. Off-grid and mini-grid systems are summarised under the term ‘distributed energy systems’ or ‘decentralised energy systems’ and provide a fast and cost efficient method for rural electrification. Applicable technologies include solar photovoltaics, wind power, small hydro power and energy from residual biomass. Those small-scale renewable energy systems offer significant reductions in fossil fuel combustion and entailed emissions of greenhouse gases. This paper reviews distributed renewable energy systems and concentrates on energy services for electricity generation in rural Africa. The second literature review deals with integrated decentralised wastewater treatment for rural areas with focus on resource recovery. The most appropriate and sustainable solution for wastewater management in any setting is the one that is economically, environmentally, and technically sound, as well as socially acceptable for the specific community. Centralised wastewater collection and treatment systems are found to be resource intensive and complex, especially for low density population regions with dispersed households. Alternatively, the approach of decentralised wastewater treatment appears as a sustainable and logical solution to address issues related to rural wastewater management. This paper presents a review of the advantages and limitations of various centralised and decentralised approaches to wastewater treatment and management. A sustainable solution to wastewater management in rural areas based on the concept of ecological sanitation, with focus on water and nutrients recovery is presented.

ABSTRACTThe environmental performance of biofuels is often assessed comparing multiple feedstocks while implications of different co-product processing options are neglected. This study presents a life cycle assessment of several co-product processing concepts of wheat- and sugar beet-based ethanol production in Germany. Inventory data are first-hand industry data presenting state-of-the-art plants. The methodology defined by the Renewable Energy Directive (RED) is applied. The cradle-to-gate investigation shows that the co-production of fodder results in lowest impacts allocated to ethanol: 37 g CO2-eq. per MJ of ethanol from sugar beets. Total impacts are lower in case of beet-based ethanol in impact categories which are dominated by emissions from cultivation, such as eutrophication and acidification. Biogas co-production results in lowest total emissions but in higher emissions allocated to ethanol. A sensitivity analysis shows how certain assumptions, such as using a different energy carrier, grain d...

Abstract Photovoltaic driven decentralized reverse osmosis plants for brackish water desalination offer a sustainable and low-emission solution for water deficiency problems, especially in arid and semi-arid regions. However, the primary challenge for this combination is how a brackish water reverse osmosis desalination (BWRO) plant based on photovoltaics (PV) can be operated continuously with high energy efficiency. Therefore, this study presents an innovative concept for a BWRO plant operated 24 h/d with a constant drinking water production capacity based on PV and pumped storage as hydraulic energy storage. The latter is used to cover the hydraulic energy consumption of the BWRO process completely or partially in times when the necessary electrical power cannot be provided by the PV plant due to missing solar radiation. During the course of the year, only 2% of the hydraulic energy to be stored in the pumped storage is lost during charging and discharging. The overall efficiency (from PV electricity to used hydraulic energy) of the pumped storage in the investigated innovative system is 78.4%. This value is 2.4% higher than the overall efficiency for a battery system with a high pressure pump in the current designs for BWRO based on PV and battery.

Abstract Until today, first generation (1G) biofuels dominate the market for alternative fuels. The European Commission decided to cap 1G biofuels and promote second generation (2G) biofuels with the intention to reduce greenhouse gas (GHG) emissions, to limit the competition of food, feed and biofuels, as well as to improve societal approval. The assessment of consequences entailed to a shift from 1G to 2G biofuels is required to judge whether such a shift is advisable or not. According to the renewable energy directive (RED), GHG savings, need to be determined for all biofuels. By the end of 2020, fuel blends need to achieve a GHG reduction of 6%. Thus, GHG savings will determine the quantity of biofuel to be blended with fossil fuels and thereby eventually define the demand for biofuels. In this paper, the consequences of a shift from a 1G to a 2G biofuel is assessed by the example of bioethanol from wheat grains and straw. In total, three concepts of 2G ethanol production from wheat straw are considered: fermentation of C6-sugars with (1) co-production of feed, (2) coupled with biogas production and (3) co-fermentation of C5- and C6-sugars with co-production of feed. To determine the effect of the introduction of 2G ethanol, GHG savings according to RED are calculated first, and, in a second step, consequences of the shift from 1G to 2G ethanol are assessed by accounting for substitution mechanisms and emissions from direct and indirect land-use change (LUC). GHG savings of these 2G concepts according to RED methodology range from 103 to 105%. The shift from 1G ethanol to these 2G concepts is assessed by two scenarios: (1) additional production of 2G ethanol and (2) the replacement of 1G ethanol by 2G ethanol. Results indicate that GHG emissions decrease in scenario 1 if all surplus ethanol replaces fossil fuels. Under the given assumptions, the reduction in emissions ranges from 9.0 to 12.1 kg CO2-eq./GJ ethanol-gasoline blend. If 1G ethanol is replaced by 2G ethanol, GHG emission increase in a range from 7.5 to 16.5 kg CO2-eq./GJ fuel blend. This is mainly due to the provision of feed that needs to be supplied as a consequence of the shift in production: 1G ethanol production provides a high protein feed that needs to be provided by other means. Hence, the main driver for an increase in emissions is the provision of soybean meal and entailed emissions from LUC. A sensitivity analysis shows that these results are robust regarding input parameters and LUC assumptions. These findings point out that it is of utmost importance to assess changes induced by the introduction of novel fuels rather than assessing them isolated from market conditions. Based on these findings, it can be concluded that current and proposed legislation might trigger effects opposed to those intended.