Zukünftige Energie- und Industriesysteme
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In the energy sector, few topics, if any, are more hyped than hydrogen. Countries develop hydrogen strategies to provide a perspective for hydrogen production and use in order to meet climate-neutrality goals. However, in this topical field the role of water is less accentuated. Hence, in this study, we seek to map the interrelations between the water and wastewater sector on the one hand and the hydrogen sector on the other hand, before reflecting upon our findings in a country case study. We chose the Hashemite Kingdom of Jordan because (i) hydrogen is politically discussed not least due to its high potentials for solar PV, and (ii) Jordan is water stressed - definitely a bad precondition for water-splitting electrolyzers. This research is based on a project called the German-Jordanian Water-Hydrogen-Dialogue (GJWHD), which started with comprehensive desk research mostly to map the intersectoral relations and to scope the situation in Jordan. Then, we carried out two expert workshops in Wuppertal, Germany, and Amman, Jordan, in order to further discuss the nexus by inviting a diverse set of stakeholders. The mapping exercise shows various options for hydrogen production and opportunities for planning hydrogen projects in water-scarce contexts such as Jordan.
Biogas and bio-methane that are based on energy crops are renewable energy carriers and therefore potentially contribute to climate protection. However, significant greenhouse gas (GHG) emissions resulting from agricultural production processes must be considered. Among those, the production and use of fertilizer, and the resulting leaching of nitrous oxide (N2O), are crucial factors. This article provides an integrated life cycle assessment (LCA) of biogas (i.e. bio-methane that has been upgraded and injected into the natural gas grid), taking into account the processes of fermentation, upgrading and injection to the grid for two different types of biogas plants. The analysis is based on different feedstocks from crop rotation systems for different locations in Germany. A special focus is on the sensitivity of assumptions of nitrous oxide emissions to overall GHG emissions. Much research exists on the measurement or modeling of the actual N2O emissions that result from farming processes. Since there is as yet no precise regional data, most analyses use tier-1 data from the IPCC national GHG inventories as a default. The present article coincides with recent research in indicating that this data varies at the regional level. However, it is not the scope of the article to evaluate the quality of existing data for N2O emissions, but to show the effects of different assumptions on the LCA of GHGs from bio-methane. Thus, a link between the provision of emission data and the practical implementation of biogas technology is provided. The main result is that the supply chain of substrates from agricultural processes appears to contribute the most to the GHG emissions of bio-methane. The "worst case" scenario where 5% of the nitrogen fertilizer used is emitted in form of N2O shows that the GHG mitigation potential of bio-methane versus natural gas is very small, so there is not much margin for error in the plant technology.
Biogas and bio-methane that are based on energy crops are renewable energy carriers and therefore potentially contribute to climate protection. However, significant greenhouse gas emissions resulting from agricultural production processes must be considered, mainly resulting from agricultural production processes, as fertilizer use, pesticide etc.
This paper provides an integrated life cycle assessment (LCA) of biogas (i.e. bio-methane that has been upgraded and injected into the natural gas grid), taking into account the processes of fermentation, upgrading and injection to the grid for two different types of biogas plants thus examining the current state of the art as well as new, large-scale plants, operated by industrial players. Not only technical and engineering aspects are taken into account here, but also the choice of feedstock which plays an important role as to the overall ecological evaluation of bio-methane.
The substrates evaluated in this paper - aside from maize - are rye, sorghum, whole-crop-silage from triticale and barley, and the innovative options of agricultural grass (Landsberger Gemenge, a mixture of hairy vetch (vicia villosa), crimson clover (trifolium incarnátum) and Italian ryegrass (lolium multiflorum)) as well as a combination of maize and sunflower.
Urban energy systems have been commonly considered to be socio-technical systems within the boundaries of an urban area. However, recent literature challenges this notion in that it urges researchers to look at the wider interactions and influences of urban energy systems wherein the socio-technical sphere is expanded to political, environmental and economic realms as well. In addition to the inter-sectoral linkages, the diverse agents and multilevel governance trends of energy sustainability in the dynamic environment of cities make the urban energy landscape a complex one. There is a strong case then for establishing a new conceptualisation of urban energy systems that builds upon these contemporary understandings of such systems. We argue that the complex systems approach can be suitable for this. In this paper, we propose a pilot framework for understanding urban energy systems using complex systems theory as an integrating plane. We review the multiple streams of urban energy literature to identify the contemporary discussions and construct this framework that can serve as a common ontological understanding for the different scholarships studying urban energy systems. We conclude the paper by highlighting the ways in which the framework can serve some of the relevant communities.
The production of commodities by energy-intensive industry is responsible for 1/3 of annual global greenhouse gas (GHG) emissions. The climate goal of the Paris Agreement, to hold the increase in the global average temperature to well below 2 °C above pre-industrial levels while pursuing efforts to limit the temperature increase to 1.5 °C, requires global GHG emissions reach net-zero and probably negative by 2055-2080. Given the average economic lifetime of industrial facilities is 20 years or more, this indicates all new investment must be net-zero emitting by 2035-2060 or be compensated by negative emissions to guarantee GHG-neutrality. We argue, based on a sample portfolio of emerging and near-commercial technologies for each sector (largely based on zero carbon electricity & heat sources, biomass and carbon capture, and catalogued in an accompanying database), that reducing energy-intensive industrial GHG emissions to Paris Agreement compatible levels may not only be technically possible, but can be achieved with sufficient prioritization and policy effort. We then review policy options to drive innovation and investment in these technologies. From this we synthesize a preliminary integrated strategy for a managed transition with minimum stranded assets, unemployment, and social trauma that recognizes the competitive and globally traded nature of commodity production. The strategy includes: an initial policy commitment followed by a national and sectoral stakeholder driven pathway process to build commitment and identify opportunities based on local zero carbon resources; penetration of near-commercial technologies through increasing valuation of GHG material intensity through GHG pricing or flexible regulations with protection for competitiveness and against carbon leakage; research and demand support for the output of pilot plants, including some combination of guaranteed above-market prices that decline with output and an increasing requirement for low carbon inputs in government procurement; and finally, key supporting institutions.
The war in Ukraine is changing the political landscape at breakneck speed. How should politics and society react to high energy prices and a precarious dependence on fossil fuels imports? Can modern societies get by with much less energy? Energy sufficiency can play an important role in answering these questions. The contributions in this Special topic explore sufficiency as an interdisciplinary research topic for energy modeling, scenarios, and policy.
Sufficiency measures are potentially decisive for the decarbonisation of energy systems but rarely considered in energy policy and modelling. Just as efficiency and renewable energies, the diffusion of demand-side solutions to climate change also relies on policy-making. Our extensive literature review of European and national sufficiency policies fills a gap in existing databases. We present almost 300 policy instruments clustered into relevant categories and publish them as "Energy Sufficiency Policy Database". This paper provides a description of the data clustering, the set-up of the database and an analysis of the policy instruments. A key insight is that sufficiency policy includes much more than bans of products or information tools leaving the responsibility to individuals. It is a comprehensive instrument mix of all policy types, not only enabling sufficiency action, but also reducing currently existing barriers. A policy database can serve as a good starting point for policy recommendations and modelling, further research is needed on barriers and demand-reduction potentials of sufficiency policy instruments.
The concept of multiple (economic, ecological, social and political) crisis has arisen from recent tumultuous economic events. This paper uses a feminist perspective to present the concept as a crisis of regeneration of both nature and social reproduction. We intend to go beyond multiple crisis using the notion of a new social contract, to overcome this crisis in a transformative way towards sustainability. A feminist analysis of the concept of social contract is founded on the critique of domination and is based on Carole Pateman's, 1988 thesis that the modern social contract is characterized by a "separating inclusion" of women. It also refers to Val Plumwood's critique of the separated and autonomous self, which is part of all classical conceptions of social contract. We argue that overcoming the multiple crisis requires overcoming structures of separation and re-envisioning concepts of the individual, by discussing the German example of a "Social Contract for Sustainability" (2011). If the notion of social contract is to become a catalyst for transformation processes leading to sustainability, it cannot be overarching but has to be developed as a multitude of small new social and local contracts.
Direct air capture (DAC) combined with subsequent storage (DACCS) is discussed as one promising carbon dioxide removal option. The aim of this paper is to analyse and comparatively classify the resource consumption (land use, renewable energy and water) and costs of possible DAC implementation pathways for Germany. The paths are based on a selected, existing climate neutrality scenario that requires the removal of 20 Mt of carbon dioxide (CO2) per year by DACCS from 2045. The analysis focuses on the so-called "low-temperature" DAC process, which might be more advantageous for Germany than the "high-temperature" one. In four case studies, we examine potential sites in northern, central and southern Germany, thereby using the most suitable renewable energies for electricity and heat generation. We show that the deployment of DAC results in large-scale land use and high energy needs. The land use in the range of 167-353 km2 results mainly from the area required for renewable energy generation. The total electrical energy demand of 14.4 TWh per year, of which 46% is needed to operate heat pumps to supply the heat demand of the DAC process, corresponds to around 1.4% of Germany's envisaged electricity demand in 2045. 20 Mt of water are provided yearly, corresponding to 40% of the city of Cologne's water demand (1.1 million inhabitants). The capture of CO2 (DAC) incurs levelised costs of 125-138 EUR per tonne of CO2, whereby the provision of the required energy via photovoltaics in southern Germany represents the lowest value of the four case studies. This does not include the costs associated with balancing its volatility. Taking into account transporting the CO2 via pipeline to the port of Wilhelmshaven, followed by transporting and sequestering the CO2 in geological storage sites in the Norwegian North Sea (DACCS), the levelised costs increase to 161-176 EUR/tCO2. Due to the longer transport distances from southern and central Germany, a northern German site using wind turbines would be the most favourable.
A cost-minimizing electricity market model was used to explore optimized infrastructures for the integration of renewable energies in interconnected North African power systems until 2030. The results show that the five countries Morocco, Algeria, Tunisia, Libya and Egypt could together achieve significant economic benefits, reaching up to EUR 3.4 billion, if they increase power system integration, build interconnectors and cooperate on joint utilization of their generation assets. Net electricity exports out of North Africa to Europe or Eastern Mediterranean regions, however, were not observed in the regime of integrated electricity markets until 2030, and could only be realized by much higher levels of renewable energy penetration than currently foreseen by North African governments.