Mixed Ehrhart polynomials

For lattice polytopes $P_1,\ldots, P_k \subseteq \mathbb{R}^d$, Bihan (2014) introduced the discrete mixed volume $\mathrm{DMV}(P_1,\dots,P_k)$ in analogy to the classical mixed volume. In this note we initiate the study of the associated mixed Ehrhart polynomial $\mathrm{ME}_{P_1,\dots,P_k}(n) = \mathrm{DMV}(nP_1,\dots,nP_k)$. We study properties of this polynomial and we give interpretations for some of its coefficients in terms of (discrete) mixed volumes. Bihan (2014) showed that the discrete mixed volume is always non-negative. Our investigations yield simpler proofs for certain special cases. We also introduce and study the associated mixed $h^*$-vector. We show that for large enough dilates $r P_1, \ldots, rP_k$ the corresponding mixed $h^*$-polynomial has only real roots and as a consequence the mixed $h^*$-vector becomes non-negative.Comment: 12 page

Techno-economic analysis of hydrogen enhanced methanol to gasoline process from biomass-derived synthesis gas

In this paper, the implications of the use of hydrogen on product yield and conversion efficiency as well as on economic performance of a hydrogen enhanced Biomass-to-Liquid (BtL) process are analyzed. A process concept for the synthesis of fuel (gasoline and LPG) from biomass-derived synthesis gas via Methanol-to-Gasoline (MtG) route with utilization of carbon dioxide from gasification by feeding additional hydrogen is developed and modeled in Aspen Plus. The modeled process produces 0.36 kg fuel per kg dry straw. Additionally, 99 MW electrical power are recovered from purge and off gases from fuel synthesis in CCGT process, covering the electricity consumption of fuel synthesis and synthesis gas generation. The hydrogen enhanced BtL procces reaches a combined chemical and electrical efficiency of 48.2% and overall carbon efficiency of 69.5%. The total product costs (TPC) sum up to 3.24 €/kg fuel. Raw materials (hydrogen and straw) make up the largest fraction of TPC with a total share of 75%. The hydrogen enhanced BtL process shows increased chemical, energy and carbon efficiencies and thus higher product yields. However, economic analysis shows that the process is unprofitable under current conditions due to high costs for hydrogen provision

Multi criteria decision analysis for sustainability assessment of 2nd generation biofuels

This paper presents results of the comparative sustainability assessment of three renewable and fossil fuel production routes, i.e. gasoline from straw or wood, and conventional gasoline. For the simultaneous consideration of the ecological, economic and social dimension a MS Excel-based tool is developed, which enables the assessment of energy technologies by choosing different MCDA (Multi Criteria Decision Analysis) methods, weighting sets, weighting methods and normalization methods for ecological indicators. Results for the MCDA method TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) show, that stakeholders who prioritize the economic dimension (Individualist) would choose conventional gasoline, while stakeholders who prioritize the ecological and the social dimension (Hierarchist and Egalitarian) would choose gasoline from wood

Entwicklung eines Energie- und Stoffstrommodells zur ökonomischen und ökologischen Bewertung der Herstellung chemischer Grundstoffe aus Lignocellulose

Ziel der vorliegenden Arbeit ist die Abschätzung der Wirtschaftlichkeit und der Umweltwirkungen der Herstellung chemischer Grundstoffe aus Holz in einer frühen Phase der Prozessentwicklung. Am Beispiel eines Organosolv-Aufschlussverfahrens für Laubholz mit einer anschließenden Trennung der Holzkomponenten Cellulose, Hemicellulose und Lignin wird ein Energie- und Stoffstrommodell zur integrierten ökonomischen und ökologischen Bewertung und Optimierung entwickelt und exemplarisch angewandt

Weighting factor elicitation for sustainability assessment of energy technologies

In this paper, an approach for sustainability assessment of innovative energy technologies is expanded by multi-criteria decision analysis (MCDA) methods to aggregate indicator results and support decision-making. One of the most important steps for MCDA is to determine weighting factors for individual indicators. Thus, a workshop was performed to elicit weighting factors for sustainability assessments of energy technologies from developers of such technologies and energy system modellers from academia. These stakeholders expressed their preferences with respect to sustainability criteria using the Simple Multi Attribute Rating Technique (SMART). A triple bottom line approach of sustainable development was used as the basis for the aggregation of indicator results. This approach is based on Life Cycle Costing, Life Cycle Assessment and social indicators. Obtained weighting factors were applied to an integrative sustainability assessment with the aggregation method Preference Ranking Organization METHod for Enrichment of Evaluations (PROMETHEE). Hydrogen-based mobility as an important technology to foster decarbonization in the transport sector is used as a case study for the application of the derived weighting factors. A conventional vehicle, powered by fossil fuel, is compared with a fuel cell electric vehicle (FCEV) for the year 2050. Different options (pipeline, compressed gaseous hydrogen, liquid hydrogen, liquid organic hydrogen carrier) are discussed for the supply of hydrogen. The results for this weighting factor set are compared with an equal weighting scenario of the three sustainability dimensions and indicators within one sustainability dimension. The FCEV, using pipelines for hydrogen supply, came out first in the assessment as well as in all sensitivity analyses

Ökonomische Bewertung der Integration temporärer Naturschutzmaßnahmen im Ökologischen Landbau - Beispiel Blühstreifen -

At the Hessian state domain Frankenhausen, an organic farm with comparatively high yield potential, the integration of nature conservation measures is tested. Economic investigations aim to identify costs and changes of performance due to the adaptation of production processes to nature conservation targets. The main focus is on temporary measures that, like field-flower strips, potentially promote biodiversity on arable land. Initial calculations show the costs that must be taken into account for wildflower strips with autochthonous species on arable land. The analysis particularly considers the complex intra-farm integration of the conservation measures as a special characteristic of organic agriculture systems

Prospective assessment of energy technologies: a comprehensive approach for sustainability assessment

Background: A further increase in renewable energy supply is needed to substitute fossil fuels and combat climate change. Each energy source and respective technologies have specific techno-economic and environmental characteristics as well as social implications. This paper presents a comprehensive approach for prospective sustainability assessment of energy technologies developed within the Helmholtz Initiative “Energy System 2050” (ES2050).Methods: The “ES2050 approach” comprises environmental, economic, and social assessment. It includes established life cycle based economic and environmental indicators, and social indicators derived from a normative concept of sustainable development. The elaborated social indicators, i.e. patent growth rate, acceptance, and domestic value added, address three different socio-technical areas, i.e. innovation (patents), public perception (acceptance), and public welfare (value added).Results: The implementation of the “ES2050 approach” is presented exemplarily and different sustainability indicators and respective results are discussed based on three emerging technologies and corresponding case studies: (1) synthetic biofuels for mobility; (2) hydrogen from wind power for mobility; and (3) batteries for stationary energy storage. For synthetic biofuel, the environmental advantages over fossil gasoline are most apparent for the impact categories Climate Change and Ionizing Radiation—human health. Domestic value added accounts for 66% for synthetic biofuel compared to 13% for fossil gasoline. All hydrogen supply options can be considered to become near to economic competitiveness with fossil fuels in the long term. Survey participants regard Explosion Hazard as the most pressing concern about hydrogen fuel stations. For Li-ion batteries, the results for patent growth rate indicate that they enter their maturity phase.Conclusions: The “ES2050 approach” enables a consistent prospective sustainability assessment of (emerging) energy technologies, supporting technology developers, decision-makers in politics, industry, and society with knowledge for further evaluation, steering, and governance. The approach presented is considered rather a starting point than a blueprint for the comprehensive assessment of renewable energy technologies though, especially for the suggested social indicators, their significance and their embedding in context scenarios for prospective assessments

Environmental Sustainability Assessment of Multi-Sectoral Energy Transformation Pathways: Methodological Approach and Case Study for Germany

In order to analyse long-term transformation pathways, energy system models generally focus on economical and technical characteristics. However, these models usually do not consider sustainability aspects such as environmental impacts. In contrast, life cycle assessment enables an extensive estimate of those impacts. Due to these complementary characteristics, the combination of energy system models and life cycle assessment thus allows comprehensive environmental sustainability assessments of technically and economically feasible energy system transformation pathways. We introduce FRITS, a FRamework for the assessment of environmental Impacts of Transformation Scenarios. FRITS links bottom-up energy system models with life cycle impact assessment indicators and quantifies the environmental impacts of transformation strategies of the entire energy system (power, heat, transport) over the transition period. We apply the framework to conduct an environmental assessment of multi-sectoral energy scenarios for Germany. Here, a ‘Target’ scenario reaching 80% reduction of energy-related direct CO2 emissions is compared with a ‘Reference’ scenario describing a less ambitious transformation pathway. The results show that compared to 2015 and the ‘Reference’ scenario, the ‘Target’ scenario performs better for most life cycle impact assessment indicators. However, the impacts of resource consumption and land use increase for the ‘Target’ scenario. These impacts are mainly caused by road passenger transport and biomass conversion

Multi criteria decision analysis for prospective sustainability assessment of alternative technologies and fuels for individual motorized transport

Reducing greenhouse gas (GHG) emissions in the transport sector is one of the biggest challenges in the German energy transition. Furthermore, sustainable development does not stop with reducing GHG emissions. Other environmental, social and economic aspects should not be neglected. Thus, here a comprehensive sustainability assessment for passenger vehicles is conducted for 2020 and 2050. The discussed options are an internal combustion engine vehicle (ICEV) fuelled with synthetic biofuel and fossil gasoline, a battery electric vehicle (BEV) with electricity from wind power and electricity mix Germany and a fuel cell electric vehicle (FCEV) with hydrogen from wind power. The life cycle-based assessment entails 13 environmental indicators, one economic and one social indicator. For integrated consideration of the different indicators, the MCDA method Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is chosen. For the assessment, a consistent assessment framework, i.e. background scenario and system boundaries, and a detailed modelling of vehicle production, fuel supply and vehicle use are the cornerstones. The BEV with wind power is the most sustainable option in 2020 as well as in 2050. While in 2020, the second rank is taken by the ICEV with synthetic biofuel from straw and the last rank by the FCEV, in 2050 the FCEV is the runner-up. With the help of MCDA, transparent and structured guidance for decision makers in terms of sustainability assessment of motorized transport options is provided