Germany
The Role of Renewable Energies, Storage and Sector-Coupling Technologies in the German Energy Sector under Different CO2 Emission Restrictions
Aug 2022
Publication
This study aimed to simulate the sector-coupled energy system of Germany in 2030 with the restriction on CO2 emission levels and to observe how the system evolves with decreasing emissions. Moreover the study presented an analysis of the interconnection between electricity heat and hydrogen and how technologies providing flexibility will react when restricting CO2 emissions levels. This investigation has not yet been carried out with the technologies under consideration in this study. It shows how the energy system behaves under different set boundaries of CO2 emissions and how the costs and technologies change with different emission levels. The study results show that the installed capacities of renewable technologies constantly increase with higher limitations on emissions. However their usage rates decreases with low CO2 emission levels in response to higher curtailed energy. The sector-coupled technologies behave differently in this regard. Heat pumps show similar behaviour while the electrolysers usage rate increases with more renewable energy penetration. The system flexibility is not primarily driven by the hydrogen sector but in low CO2 emission level scenarios the flexibility shifts towards the heating sector and electrical batteries.
Renewable Methanol Synthesis
Oct 2019
Publication
Renewable methanol production is an emerging technology that bridges the gap in the shift from fossil fuel to renewable energy. Two thirds of the global emission of CO2 stems from humanity’s increasing energy need from fossil fuels. Renewable energy mainly from solar and wind energy suffers from supply intermittency which current grid infrastructures cannot accommodate. Excess renewable energy can be harnessed to power the electrolysis of water to produce hydrogen which can be used in the catalytic hydrogenation of waste CO2 to produce renewable methanol. This review considers methanol production in the current context regionally for Europe which is dominated by Germany and globally by China. Appropriate carbon-based feedstock for renewable methanol production is considered as well as state-of-the-art renewable hydrogen production technologies. The economics of renewable methanol production necessitates the consideration of regionally relevant methanol derivatives. The thermodynamics kinetics catalytic reaction mechanism operating conditions and reactor design are reviewed in the context of renewable methanol production to reveal the most up to date understanding.
Risks and Opportunities Associated with Decarbonising Rotterdam’s Industrial Cluster
Jun 2019
Publication
The Port of Rotterdam is an important industrial cluster comprising mainly oil refining chemical production and power generation. In 2016 the port’s industry accounted for 19% of the Netherlands’ total CO2 emissions. The Port of Rotterdam Authority is aware that the cluster is heavily exposed to future decarbonisation policies as most of its activities focus on trading handling converting and using fossil fuels. Based on a study for the Port Authority using a mixture of qualitative and quantitative methods our article explores three pathways whereby the port’s industry can maintain its strong position while significantly reducing its CO2 emissions and related risks by 2050. The pathways differ in terms of the EU’s assumed climate change mitigation ambitions and the key technological choices made by the cluster’s companies. The focus of the paper is on identifying key risks associated with each scenario and ways in which these could be mitigated.
Strategic Policy Targets and the Contribution of Hydrogen in a 100% Renewable European Power System
Jul 2021
Publication
The goal of the European energy policy is to achieve climate neutrality. The long-term energy strategies of various European countries include additional targets such as the diversification of energy sources maintenance of security of supply and reduction of import dependency. When optimizing energy systems these strategic policy targets are often only considered in a rudimentary manner and thus the understanding of the corresponding interdependencies is lacking. Moreover hydrogen is considered as a key component of a fully decarbonized energy system but its role in the power sector remains unclear due to the low round-trip efficiencies. This study reveals how fully decarbonized European power systems can benefit from hydrogen in terms of overall system costs and the achievement of strategic policy targets. We analyzed a broad spectrum of scenarios using an energy system optimization model and varied model constraints that reflect strategic policy targets. Our results are threefold. First compared to power systems without hydrogen systems using hydrogen realize savings of 14–16% in terms of the total system costs. Second the implementation of a hydrogen infrastructure reduces the number of infeasible scenarios when structural policy targets are considered within the power system. Third the role of hydrogen is highly diverse at a national level. Particularly in countries with low renewable energy potential hydrogen plays a crucial role. Here high levels of self-sufficiency and security of supply are achieved by deploying hydrogen-based power generation of up to 46% of their annual electricity demand realized via imports of green hydrogen.
A Holistic Consideration of Megawatt Electrolysis as a Key Component of Sector Coupling
May 2022
Publication
In the future hydrogen (H2) will play a significant role in the sustainable supply of energy and raw materials to various sectors. Therefore the electrolysis of water required for industrial‐ scale H2 production represents a key component in the generation of renewable electricity. Within the scope of fundamental research work on cell components for polymer electrolyte membrane (PEM) electrolyzers and application‐oriented living labs an MW electrolysis system was used to further improve industrial‐scale electrolysis technology in terms of its basic structure and systems‐ related integration. The planning of this work as well as the analytical and technical approaches taken along with the essential results of research and development are presented herein. The focus of this study is the test facility for a megawatt PEM electrolysis stack with the presentation of the design processing and assembly of the main components of the facility and stack.
Demand Side Management Based Power-to-Heat and Power-to-Gas Optimization Strategies for PV and Wind Self-Consumption in a Residential Building Cluster
Oct 2021
Publication
The volatility of renewable energy sources (RES) poses a growing problem for operation of electricity grids. In contrary the necessary decarbonisation of sectors such as heat supply and transport requires a rapid expansion of RES. Load management in the context of power-to-heat systems can help to simultaneously couple the electricity and heat sectors and stabilise the electricity grid thus enabling a higher share of RES. In addition power-to-hydrogen offers the possibility of long-term energy storage options. Within this work we present a novel optimization approach for heat pump operation with the aim to counteract the volatility and enable a higher usage of RES. For this purpose a detailed simulation model of buildings and their energy supply systems is created calibrated and validated based on a plus energy settlement. Subsequently the potential of optimized operation is determined with regard to PV and small wind turbine self-consumption. In addition the potential of seasonal hydrogen storage is examined. The results show that on a daily basis a 33% reduction of electricity demand from grid is possible. However the average optimization potential is reduced significantly by prediction inaccuracy. The addition of a hydrogen system for seasonal energy storage basically eliminates the carbon dioxide emissions of the cluster. However this comes at high carbon dioxide prevention costs of 1.76 e kg−1 .
Challenges in the Decarbonization of the Energy Sector
Jun 2020
Publication
In order to limit the effects of climate change the carbon dioxide emissions associated with the energy sector need to be reduced. Significant reductions can be achieved by using appropriate technologies and policies. In the context of recent discussions about climate change and energy transition this article critically reviews some technologies policies and frequently discussed solutions. The options for carbon emission reductions are grouped into (1) generation of secondary energy carriers (2) end-use energy sectors and (3) sector interdependencies. The challenges on the way to a decarbonized energy sector are identified with respect to environmental sustainability security of energy supply economic stability and social aspects. A global carbon tax is the most promising instrument to accelerate the process of decarbonization. Nevertheless this process will be very challenging for humanity due to high capital requirements the competition among energy sectors for decarbonization options inconsistent environmental policies and public acceptance of changes in energy use.
Analyzing the Necessity of Hydrogen Imports for Net-zero Emission Scenarios in Japan
Jun 2021
Publication
With Japan’s current plans to reach a fully decarbonized society by 2050 and establish a hydrogen society substantial changes to its energy system need to be made. Due to the limited land availability in Japan significant amounts of hydrogen are planned to be imported to reach both targets. In this paper a novel stochastic version of the open-source multi-sectoral Global Energy System Model in conjunction with a power system dispatch model is used to analyze the impacts of both availability and price of hydrogen imports on the transformation of the Japanese energy system considering a net-zero emission target. This analysis highlights that hydrogen poses a valuable resource in specific sectors of the energy system. Therefore importing hydrogen can indeed positively impact energy system developments although up to 19mt of hydrogen will be imported in the case with the cheapest available hydrogen. In contrast without any hydrogen imports power demand nearly doubles in 2050 compared to 2019 due to extensive electrification in non-electricity sectors. However hydrogen imports are not necessarily required to reach net-zero emissions. In all cases however large-scale investments into renewable energy sources need to be made.
Mg-based Materials for Hydrogen Storage
Aug 2021
Publication
Over the last decade’s magnesium and magnesium based compounds have been intensively investigated as potential hydrogen storage as well as thermal energy storage materials due to their abundance and availability as well as their extraordinary high gravimetric and volumetric storage densities. This review work provides a broad overview of the most appealing systems and of their hydrogenation/dehydrogenation properties. Special emphasis is placed on reviewing the efforts made by the scientific community in improving the material’s thermodynamic and kinetic properties while maintaining a high hydrogen storage capacity.
Multiscale Modelling of Hydrogen Transport and Segregation in Polycrystalline Steels
Jun 2018
Publication
A key issue in understanding and effectively managing hydrogen embrittlement in complex alloys is identifying and exploiting the critical role of the various defects involved. A chemo-mechanical model for hydrogen diffusion is developed taking into account stress gradients in the material as well as microstructural trapping sites such as grain boundaries and dislocations. In particular the energetic parameters used in this coupled approach are determined from ab initio calculations. Complementary experimental investigations that are presented show that a numerical approach capable of massive scale-bridging up to the macroscale is required. Due to the wide range of length scales accounted for we apply homogenisation schemes for the hydrogen concentration to reach simulation dimensions comparable to metallurgical process scales. Via a representative volume element approach an ab initio based scale bridging description of dislocation-induced hydrogen aggregation is easily accessible. When we extend the representative volume approach to also include an analytical approximation for the ab initio based description of grain boundaries we find conceptual limitations that hinder a quantitative comparison to experimental data in the current stage. Based on this understanding the development of improved strategies for further efficient scale bridging approaches is foreseen.
Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage
Apr 2018
Publication
Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20–50 kJ/mol H2 to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H2 and (iii) fast sorption kinetics below 110 ◦C is strongly recommended. Among the known hydrogen storage materials amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however some barriers still have to be overcome before considering this class of material mature for real applications. In this review the most relevant progresses made in the recent years as well as the kinetic and thermodynamic properties experimentally measured for the most promising systems are reported and properly discussed.
Cold Hydrogen Blowdown Release: An Inter-comparison Study
Sep 2021
Publication
Hydrogen dispersion in stagnant environment resulting from blowdown of a vessel storing the gas at cryogenic temperature is simulated using different CFD codes and modelling strategies. The simulations are based on the DISCHA experiments that were carried out by Karlsruhe Institute of Technology (KIT) and Pro-Science (PS). The selected test for the current study involves hydrogen release from a 2.815 dm3 volume tank with an initial pressure of 200 barg and temperature 80 K. During the release the hydrogen pressure in the tank gradually decreased. A total of about 139 gr hydrogen is released through a 4 mm diameter. The temperature time series and the temperature decay rate of the minimum value predicted by the different codes are compared with each other and with the experimentally measured ones. Recommendations for future experimental setup and for modeling approaches for similar releases are provided based on the present analysis. The work is carried out within the EU-funded project PRESLHY.
Renewable Power-to-Gas: A Technological and Economic Review
Aug 2015
Publication
The Power-to-Gas (PtG) process chain could play a significant role in the future energy system. Renewable electric energy can be transformed into storable methane via electrolysis and subsequent methanation. This article compares the available electrolysis and methanation technologies with respect to the stringent requirements of the PtG chain such as low CAPEX high efficiency and high flexibility. Three water electrolysis technologies are considered: alkaline electrolysis PEM electrolysis and solid oxide electrolysis. Alkaline electrolysis is currently the cheapest technology; however in the future PEM electrolysis could be better suited for the PtG process chain. Solid oxide electrolysis could also be an option in future especially if heat sources are available. Several different reactor concepts can be used for the methanation reaction. For catalytic methanation typically fixed-bed reactors are used; however novel reactor concepts such as three-phase methanation and micro reactors are currently under development. Another approach is the biochemical conversion. The bioprocess takes place in aqueous solutions and close to ambient temperatures. Finally the whole process chain is discussed. Critical aspects of the PtG process are the availability of CO2 sources the dynamic behaviour of the individual process steps and especially the economics as well as the efficiency.
Hydrogen and Hydrogen-derived Fuels through Methane Decomposition of Natural Gas – GHG Emissions and Costs
May 2020
Publication
Hydrogen can be produced from the decomposition of methane (also called pyrolysis). Many studies assume that this process emits few greenhouse gas (GHG) because the reaction from methane to hydrogen yields only solid carbon and no CO2. This paper assesses the life-cycle GHG emissions and the levelized costs for hydrogen provision from methane decomposition in three configurations (plasma molten metal and thermal gas). The results of these configurations are then compared to electrolysis and steam methane reforming (SMR) with and without CO2capture and storage (CCS). Under the global natural gas supply chain conditions hydrogen from methane decomposition still causes significant GHG emissions between 43 and 97 g CO2-eq./MJ. The bandwidth is predominately determined by the energy source providing the process heat i.e. the lowest emissions are caused by the plasma system using renewable electricity. This configuration shows lower GHG emissions compared to the “classical” SMR (99 g CO2-eq./MJ) but similar emissions to the SMR with CCS (46 g CO2-eq./MJ). However only electrolysis powered with renewable electricity leads to very low GHG emissions (3 g CO2-eq./MJ). Overall the natural gas supply is a decisive factor in determining GHG emissions. A natural gas supply with below-global average GHG emissions can lead to lower GHG emissions of all methane decomposition configurations compared to SMR. Methane decomposition systems (1.6 to 2.2 €/kg H2) produce hydrogen at costs substantially higher compared to SMR (1.0 to 1.2 €/kg) but lower than electrolyser (2.5 to 3.0 €/kg). SMR with CCS has the lowest CO2abatement costs (24 €/t CO2-eq. other > 141 €/t CO2-eq.). Finally fuels derived from different hydrogen supply options are assessed. Substantially lower GHG emissions compared to the fossil reference (natural gas and diesel/gasoline) are only possible if hydrogen from electrolysis powered by renewable energy is used (>90% less). The other hydrogen pathways cause only slightly lower or even higher GHG emissions.
On the Climate Impacts of Blue Hydrogen Production
Nov 2021
Publication
Natural gas based hydrogen production with carbon capture and storage is referred to as blue hydrogen. If substantial amounts of CO2 from natural gas reforming are captured and permanently stored such hydrogen could be a low-carbon energy carrier. However recent research raises questions about the effective climate impacts of blue hydrogen from a life cycle perspective. Our analysis sheds light on the relevant issues and provides a balanced perspective on the impacts on climate change associated with blue hydrogen. We show that such impacts may indeed vary over large ranges and depend on only a few key parameters: the methane emission rate of the natural gas supply chain the CO2 removal rate at the hydrogen production plant and the global warming metric applied. State-of-the-art reforming with high CO2 capture rates combined with natural gas supply featuring low methane emissions does indeed allow for substantial reduction of greenhouse gas emissions compared to both conventional natural gas reforming and direct combustion of natural gas. Under such conditions blue hydrogen is compatible with low-carbon economies and exhibits climate change impacts at the upper end of the range of those caused by hydrogen production from renewable-based electricity. However neither current blue nor green hydrogen production pathways render fully “net-zero” hydrogen without additional CO2 removal.
Decarbonizing the German Industrial Thermal Energy Use with Solar, Hydrogen, and Other Options - Recommendations for the World
Nov 2022
Publication
This paper is based on a position paper of the German Industry Association Concentrated Solar Power e.V. to the German government and discusses options on how to decarbonize the heat demand of the domestic industry. Among other option concentration solar collectors are a suitable option in Germany which has not been expected by many experts. The paper derives requirements that are needed to ensure a quick and sustainable way to decarbonize industrial heat demand. They are considered to also be relevant for many other countries that follow the same ambition to become climate neutral in the next decades. They major statements are: A mix of different renewable energy technologies in conjunction with efficiency measures is needed to ensure a secure climate-friendly and cost-efficient heat supply for the industry; The different technology options for the provision of heat from renewable sources through electrification and through hydrogen can and must be combined and integrated with each other. In this context concentrating solar thermal represents an important part of the hybrid supply portfolio of a decarbonized industry This requires: The definition of an expansion target for process heat and the flanking measures; Ensuring the equivalence of renewable heat renewable electricity and green hydrogen - also as hybrid solutions; The promotion of concentrating solar thermal reference projects as an impetus for market ramp-up in Germany; The launch of an information campaign for heat consumers and the establishment of a pool of consultants.
Quantification of Hydrogen in Nanostructured Hydrogenated Passivating Contacts for Silicon Photovoltaics Combining SIMS-APT-TEM: A Multiscale Correlative Approach
Mar 2021
Publication
Multiscale characterization of the hydrogenation process of silicon solar cell contacts based on c-Si/SiOx/nc-SiCx(p) has been performed by combining dynamic secondary ion mass-spectrometry (D-SIMS) atom probe tomography (APT) and transmission electron microscopy (TEM). These contacts are formed by high-temperature firing which triggers the crystallization of SiCx followed by a hydrogenation process to passivate remaining interfacial defects. Due to the difficulty of characterizing hydrogen at the nm-scale the exact hydrogenation mechanisms have remained elusive. Using a correlative TEM-SIMS-APT analysis we are able to locate hydrogen trap sites and quantify the hydrogen content. Deuterium (D) a heavier isotope of hydrogen is used to distinguish hydrogen introduced during hydrogenation from its background signal. D-SIMS is used due to its high sensitivity to get an accurate deuterium-to-hydrogen ratio which is then used to correct deuterium profiles extracted from APT reconstructions. This new methodology to quantify the concentration of trapped hydrogen in nm-scale structures sheds new insights on hydrogen distribution in technologically important photovoltaic materials.
Hydrogen Supply Chains for Mobility—Environmental and Economic Assessment
May 2018
Publication
Hydrogen mobility is one option for reducing local emissions avoiding greenhouse gas (GHG) emissions and moving away from a mainly oil-based transport system towards a diversification of energy sources. As hydrogen production can be based on a broad variety of technologies already existing or under development a comprehensive assessment of the different supply chains is necessary regarding not only costs but also diverse environmental impacts. Therefore in this paper a broad variety of hydrogen production technologies using different energy sources renewable and fossil are exemplarily assessed with the help of a Life Cycle Assessment and a cost assessment for Germany. As environmental impacts along with the impact category Climate change five more advanced impact categories are assessed. The results show that from an environmental point of view PEM and alkaline electrolysis are characterized by the lowest results in five out of six impact categories. Supply chains using fossil fuels in contrast have the lowest supply costs; this is true e.g. for steam methane reforming. Solar powered hydrogen production shows low impacts during hydrogen production but high impacts for transport and distribution to Germany. There is no single supply chain that is the most promising for every aspect assessed here. Either costs have to be lowered further or supply chains with selected environmental impacts have to be modified.
Power-to-Gas and Power-to-X—The History and Results of Developing a New Storage Concept
Oct 2021
Publication
Germany’s energy transition known as ‘Energiewende’ was always very progressive. However it came technically to a halt at the question of large-scale seasonal energy storage for wind and solar which was not available. At the end of the 2000s we combined our knowledge of both electrical and process engineering imitated nature by copying photosynthesis and developed Power-to-Gas by combining water electrolysis with CO2 -methanation to convert water and CO2 together with wind and solar power to synthetic natural gas. Storing green energy by coupling the electricity with the gas sector using its vast TWh-scale storage facility was the solution for the biggest energy problem of our time. This was the first concept that created the term ‘sector coupling’ or ‘sectoral integration’. We first implemented demo sites presented our work in research industry and ministries and applied it in many macroeconomic studies. It was an initial idea that inspired others to rethink electricity as well as eFuels as an energy source and energy carrier. We developed the concept further to include Power-to-Liquid Power-to-Chemicals and other ways to ‘convert’ electricity into molecules and climate-neutral feedstocks and named it ‘Power-to-X’ at the beginning of the 2010s.
Response Time Measurement of Hydrogen Sensors
Sep 2017
Publication
The efficiency of gas sensor application for facilitating the safe use of hydrogen depends considerably on the sensor response to a change in hydrogen concentration. Therefore the response time has been measured for five different-type commercially available hydrogen sensors. Experiments showed that all these sensors surpass the ISO 26142 standard; for the response times t90 values of 2 s to 16 s were estimated. Results can be fitted with an exponential or sigmoidal function. It can be demonstrated that the results on transient behaviour depend on both the operating parameters of sensors and investigation methods as well as on the experimental conditions: gas change rate and concentration jump.
No more items...