Zukünftige Energie- und Industriesysteme
Um den Klimawandel begrenzen zu können, wird zunehmend der Einsatz von Direct Air Capture (DAC) zur Erzeugung von Negativemissionen diskutiert. Anhand von Kosten sowie dem Flächen-, Wasser- und Energieverbrauch werden in diesem Artikel mögliche Implementierungspfade der DAC-Technologie, aufbauend auf einem bestehenden Klimaneutralitätsszenario für Deutschland, analysiert. Während die technische Realisierung machbar sein sollte, stellt der hohe Flächen- und Energiebedarf eine kritische Größe dar.
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.
This study provides insight into the feasibility of a CO2 trunkline from the Netherlands to the Utsira formation in the Norwegian part of the North Sea, which is a large geological storage reservoir for CO2. The feasibility is investigated in competition with CO2 storage in onshore and near-offshore sinks in the Netherlands. Least-cost modelling with a MARKAL model in combination with ArcGIS was used to assess the cost-effectiveness of the trunkline as part of aDutch greenhouse gas emission reduction strategy for the Dutch electricity sector and CO2 intensive industry. The results show that under the condition that a CO2 permit price increases from €25 per tCO2 in 2010 to €60 per tCO2 in 2030, and remains at this level up to 2050, CO2 emissions in the Netherlands could reduce with 67% in 2050 compared to 1990, and investment in the Utsira trunkline may be cost-effective from 2020–2030 provided that Belgian and German CO2 is transported and stored via the Netherlands as well. In this case, by 2050 more than 2.1 GtCO2 would have been transported from the Netherlands to the Utsira formation. However, if the Utsira trunkline is not used for transportation of CO2 from Belgium and Germany, it may become cost-effective 10 years later, and less than 1.3 GtCO2 from the Netherlands would have been stored in the Utsiraformation by 2050. On the short term, CO2 storage in Dutch fields appears more cost-effective than in the Utsira formation, but as yet there are major uncertainties related to the timing and effective exploitation of the Dutch offshore storage opportunities.
One of the factors decelerating a further diffusion of the carbon capture and storage (CCS) technology is the public's negative perception of early pilot or demonstration activities in Germany as well as in other countries. This study examined the public perception of CCS in more detail by looking into different options within the CCS chain, i.e. for the three elements capture, transport and storage. This was analyzed using an experimental approach, realized in an online survey with a representative German sample of 1830 citizens. Each participant evaluated one of 18 different CCS scenarios created using three types of CO2 source (industry, biomass, coal), two transport options (pipeline vs. no specification), and three storage possibilities (saline aquifer, depleted gas field, enhanced gas recovery (EGR)).
Overall, we found that the ratings of CCS were neutral on average. However, if the CO2 is produced by a biomass power plant or industry, CCS is rated more positively than in a scenario with a coal-fired power plant. The specifications of transport and storage interacted with each other such that scenarios including EGR or a depleted gas field without mentioning a pipeline were evaluated better than storing it in a saline aquifer or a depleted gas field and mentioning a pipeline as means of transport. Exploratory regression analyses indicate the high relevance of the respective CO2 source in general as well as the perceived importance of this source for Germany.
Green hydrogen and synthetic fuels are increasingly recognized as a key strategic element for the progress of the global energy transition. The Middle East and North Africa (MENA) region, with its large wind and solar potential, is well positioned to generate renewable energy at low cost for the production of green hydrogen and synthetic fuels, and is therefore considered as a potential future producer and exporter. Yet, while solar and wind energy potentials are essential, other factors are expected to play an equally important role for the development of green hydrogen and synthetic fuels (export) sectors. This includes, in particular, adequate industrial capacities and infrastructures. These preconditions vary from country to country, and while they have been often mentioned in the discussion on green hydrogen exports, they have only been examined to a limited extent. This paper employs a case study approach to assess the existing infrastructural and industrial conditions in Jordan, Morocco, and Oman for the development of a green hydrogen and downstream synthetic fuel (export) sector.
Roadmaps for India's energy future foresee that coal power will continue to play a considerable role until the middle of the 21st century. Among other options, carbon capture and storage (CCS) is being considered as a potential technology for decarbonising the power sector. Consequently, it is important to quantify the relative benefits and trade-offs of coal-CCS in comparison to its competing renewable power sources from multiple sustainability perspectives. In this paper, we assess coal-CCS pathways in India up to 2050 and compare coal-CCS with conventional coal, solar PV and wind power sources through an integrated assessment approach coupled with a nexus perspective (energy-cost-climate-water nexus). Our levelized costs assessment reveals that coal-CCS is expensive and significant cost reductions would be needed for CCS to compete in the Indian power market. In addition, although carbon pricing could make coal-CCS competitive in relation to conventional coal power plants, it cannot influence the lack of competitiveness of coal-CCS with respect to renewables. From a climate perspective, CCS can significantly reduce the life cycle GHG emissions of conventional coal power plants, but renewables are better positioned than coal-CCS if the goal is ambitious climate change mitigation. Our water footprint assessment reveals that coal-CCS consumes an enormous volume of water resources in comparison to conventional coal and, in particular, to renewables. To conclude, our findings highlight that coal-CCS not only suffers from typical new technology development related challenges - such as a lack of technical potential assessments and necessary support infrastructure, and high costs - but also from severe resource constraints (especially water) in an era of global warming and the competition from outperforming renewable power sources. Our study, therefore, adds a considerable level of techno-economic and environmental nexus specificity to the current debate about coal-based large-scale CCS and the low carbon energy transition in emerging and developing economies in the Global South.
New energy technologies may fail to make the transition to the market once research funding has ended due to a lack of private engagement to conclude their development. Extending public funding to cover such experimental developments could be one way to improve this transition. However, identifying promising research and development (R&D) proposals for this purpose is a difficult task for the following reasons: Close-to-market implementations regularly require substantial resources while public budgets are limited; the allocation of public funds needs to be fair, open, and documented; the evaluation is complex and subject to public sector regulations for public engagement in R&D funding. This calls for a rigorous evaluation process. This paper proposes an operational three-staged decision support system (DSS) to assist decision-makers in public funding institutions in the ex-ante evaluation of R&D proposals for large-scale close-to-market projects in energy research. The system was developed based on a review of literature and related approaches from practice combined with a series of workshops with practitioners from German public funding institutions. The results confirm that the decision-making process is a complex one that is not limited to simply scoring R&D proposals. Decision-makers also have to deal with various additional issues such as determining the state of technological development, verifying market failures or considering existing funding portfolios. The DSS that is suggested in this paper is unique in the sense that it goes beyond mere multi-criteria aggregation procedures and addresses these issues as well to help guide decision-makers in public institutions through the evaluation process.
The German Energiewende is a deliberate transformation of an established industrial economy towards a nearly CO2-free energy system accompanied by a phase out of nuclear energy. Its governance requires knowledge on how to steer the transition from the existing status quo to the target situation (transformation knowledge). The energy system is, however, a complex socio-technical system whose dynamics are influenced by behavioural and institutional aspects, which are badly represented by the dominant techno-economic scenario studies. In this paper, we therefore investigate and identify characteristics of model studies that make agent-based modelling supportive for the generation of transformation knowledge for the Energiewende. This is done by reflecting on the experiences gained from four different applications of agent-based models. In particular, we analyse whether the studies have improved our understanding of policies' impacts on the energy system, whether the knowledge derived is useful for practitioners, how valid understanding derived by the studies is, and whether the insights can be used beyond the initial case-studies. We conclude that agent-based modelling has a high potential to generate transformation knowledge, but that the design of projects in which the models are developed and used is of major importance to reap this potential. Well-informed and goal-oriented stakeholder involvement and a strong collaboration between data collection and model development are crucial.
Facing the uncertainty of CO2 storage capacity in China by developing different storage scenarios
(2016)
China is very active in the research and development of CO2 capture and storage technologies (CCS). However, existing estimates for CO2 storage capacity are very uncertain. This uncertainty is due to limited geological knowledge, a lack of large-scale research on CO2 injection, and different assessment approaches and parameter settings. Hence storage scenarios represent a method that can be used by policy makers to demonstrate the range of possible storage capacity developments, to help interpret uncertain results and to identify the limitations of existing assessments. In this paper, three storage scenarios are developed for China by evaluating China-wide studies supplemented with more detailed site- and basin-specific assessments. It is estimated that the greatest storage potential can be found in deep saline aquifers. Oil and gas fields may also be used. Coal seams are only included in the highest storage scenario. In total, the scenarios presented demonstrate that China has an effective storage capacity of between 65 and 1551 Gt of CO2. Furthermore, the authors emphasise a need for action to harmonise storage capacity assessment approaches due to the uncertainties involved in the capacity assessments analysed in this study.
For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. One important aspect in storage development is the storage integration into the power plant. A modular operation concept for thermal storage systems was previously suggested by DLR, showing an increase in storage capacity of more than 100 %. However, in these investigations, the additional costs needed to implement this storage concept into the power plant, like for extra piping, valves, pumps and control had not been considered. These aspects are discussed in this paper, showing a decrease of levelized energy costs with modular storage integration of 2 to 3 %. In a Life Cycle Assessment (LCA) a comparison of an AndaSol-I type solar thermal power plant [1] with the original two-tank molten salt storage and with a "hypothetical" concrete storage shows an advantage of the concrete storage technology concerning environmental impacts. The environmental impacts of the “hypothetical” concrete based AndaSol-I decrease by 7 %, considering 1 kWh of solar electricity delivered to the grid. Regarding only the production of the power plant, the emissions decrease by 9.5 %.