• Energy Research

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.

Abstract Foliage is a biogenic material occurring outside the tropical areas typically in autumn. This material is mostly not used for the production of energy because foliage is often characterized by a very high moisture and ash content as well as adhering impurities. Cleaning and drying are very energy-intensive; i.e. the additional energy used for drying is often in no relation to the possible energy yield. In such cases, heat-induced autoclave pre-treatment could be used to improve the solid biofuel properties of the foliage with regard to a subsequent energetic utilization. Here the effects of temperature, residence time and initial water content during autoclave pre-treatment were determined for foliage. The results show that such an autoclave pre-treatment can significantly improve higher heating value by 15 %, grindability, drying behaviour and concurrently reduces moisture content up to 30 wt% and equilibrium moisture content over 40 wt%. Thereby, the investigated effects can only insignificantly reduce the amount of inorganic components and should be separated before autoclave pre-treatment. The optimum operating conditions identified in this study also indicate that temperatures of 170 °C, at residence times of 3 h and an initial water content of the foliage of 50 wt% lead to an improvement of the solid biofuel properties.

The Circular Economy Action Plan, as part of the European Green Deal announced by the European Commission, is highly relevant to the chemical industry in relation to the production of sustainable products. Accordingly, the chemical industry faces the question of how far it can promote its own manufacture of sustainable products. Within this context, this article presents an approach on how to measure innovations in bioeconomy. The methodological framework developed provides the chemical industry with an approach to assess the effectiveness of innovative conversion technologies producing biogenic intermediate products (e.g., bulk chemicals). The innovations within the bioeconomy (TRL > 4; TRL—technology readiness level) are compared in terms of technical, economic, and environmental indicators for the current status, for the medium- and long-term as well as for different production sites. The methodological approach developed here is exemplarily applied, assessing the production of intermediate biogenic products via thermo-chemical conversion of lignocellulosic biomass. The results show the successful applicability of the developed assessment approach as well as significant differences in efficiency, costs, and environmental impact, both from the perspective of time and in spatial terms within the European Union. Thus, the methodological approach developed and presented enables the chemical industry to reduce challenges and to take advantage of the opportunities arising from the transition to a climate-neutral and circular economy.

Evaluating the energy demand of heating, ventilation and air conditioning (HVAC) as well as lighting equipment through standardized calculation methods has become a self-evident measure for planning and optimizing non-residential buildings in recent years. For the case of hospitals however, information about the magnitude of electricity consumption caused by the vast amounts of medical equipment is still lacking. Not least due to the strongly growing use of such electrically operated devices in an increasingly complex environment, electricity has become the major energy cost driver in modern hospitals. Against this background this paper presents a model approach based on over 33,500 h of measurements within a modern University Medical Center of Hamburg/Germany to assess the time-dependent course as well as the weekly sum of the demand for electrical energy due to medical laboratory plug loads. This assessment method allows for approximating the electricity demand of the installed equipment as a supplement to the established prediction methods for the electricity demand of HVAC, lighting, etc. It was found that only a few plug load groups contribute the greater part of the total electrical energy demand. Cumulative load predictions for a full building were possible with an error of less than 6%.

MENA countries published national policy targets for the implementation of electricity from renewable energy (RE). These targets are important as they serve as framework for stakeholders in the energy sector like businesses and administration, while also showing governmental ambitions to the public. This paper investigates the impact on resources, generation cost and GHG emissions if the targets are met. It also examines whether the current development is achieving the targets and how the targets perform in the light of the Paris Agreement. 13 to 52 % of electricity from RE is targeted for 2030. The necessary RE expansion exceeds the current expansion in most countries. Only in Morocco and Jordan are projects indicating that the targets might be reached. From a resource perspective, a much stronger expansion is possible. Beneficial locations exist allowing to cover the domestic demand or even an export of electrical energy or derived energy carrier. Furthermore, especially PV, but also wind systems, can generate electricity in many areas for lower cost than fossil fuel fired power plants. Specific GHG emissions of national electricity production in 2017 are estimated to 396���682 gCO2e/kWh and decrease to 341���514 gCO2e/kWh if the 2030 RE targets are met. The type of fossil fuel has a strong impact on the GHG emissions. Although Morocco has highest RE deployment today and targets highest RE share in 2030, it shows today and in 2030 specific GHG emissions that are among the highest of considered MENA countries because electricity production from coal dominates whereas other countries use mainly natural gas. Existing policy targets decrease specific GHG emissions until 2030. However, stronger GHG mitigation efforts will be necessary afterwards in order to reach targets of the Paris Agreement. More ambitious 2030 policy target would distribute the load more evenly over time and should be reconsidered.

Abstract Three low-grade carbonaceous materials from biomass (Scenedesmus algae and wheat straw) and waste treatment (sewage sludge) have been selected as feedstock for solar-driven thermochemical processes. Solar-driven pyrolysis and gasification measurements were conducted directly irradiating the samples in a 7 kWe high flux solar simulator and the released gases H2, CO, CO2 and CH4 and the sample temperature were continuously monitored. Solar-driven experiments showed that H2 and CO evolved as important product gases demonstrating the high quality of syngas production for the three feedstocks. Straw is the more suitable feedstock for solar-driven processes due to the high gas production yields. Comparing the solar-driven experiments, gasification generates higher percentage of syngas (mix of CO and H2) respect to total gas produced (sum of H2, CO, CO2 and CH4) than pyrolysis. Thus, solar-driven gasification generates better quality of syngas production than pyrolysis.

Green hydrogen plays a major role in the net-zero greenhouse gas-reduction strategy of the European Union. To supply hydrogen as cheap as possible, a well-balanced production system is needed to handle fluctuations of solar radiation and wind energy. Thus, this paper investigates the onsite hydrogen supply costs in the European catchment area in 2020, 2030, 2040 and 2050. Furthermore, a subsequent transport per pipeline to one of the projected demand centres in Europe (exemplary Germany) is considered. Also, the sensitivity regarding the additional use of salt caverns as hydrogen storage and less restricting supply profiles is assessed as well as the technical annual supply potential for 2030 and 2050. To do so, the optimal system design for minimized hydrogen supply cost for water electrolysis based on photovoltaic and wind turbines is estimated for a 0.5° x 0.5° grid using a linear optimization model. For the best locations, coastal regions at the North Sea, Western Sahara and parts of Algeria, onsite hydrogen supply cost decreases from 3 €2020/kgH2 in 2030 to 2 €2020/kgH2 in 2050. The technical hydrogen supply potential is tremendous, especially from Northern Africa, and a supply to Central Europe (Germany) via pipeline for around 3 €2020/kgH2 is possible in 2050, while a domestic hydrogen production in Germany covering the projected demand would lead to cost up to 4.5 €2020/kgH2. Furthermore, a large scale hydrogen storage e.g. in salt caverns, can reduce the hydrogen supply costs for regions with high seasonality of solar and wind up to 50% and excess electricity to less than 10%, leading to fewer cost deviations between the sub-regions, resulting in lower import costs from Northern and Western Europe than from Northern Africa or Middle East.