[en] In the coming years, the German energy system will be transformed towards greenhouse gas neutrality. The process for this was significantly accelerated in 2021 by the decision of the Federal Constitutional Court, bringing forward the target year to 2045 and sharpening and specifying the interim targets more precisely. In the meantime, a number of analyses are available on what such an energy system will look like in 2045. The energy supply in Germany will be based primarily on the renewable energy sources of sun and wind. Recently, however, the secondary energy carrier hydrogen has also become the focus of discussion, as it will also play a role in a greenhouse gas-neutral energy system. The main reasons for this are that hydrogen is producible from renewable energies and - although not entirely easy - storable and transportable, and does not require carbon molecules and the associated emissions.

[en] The costs of producing electricity from renewable resources have dropped significantly and are now approaching those of production based on fossil fuels. A recent study by the Fraunhofer Institute for Solar Energy Systems shows that by the year 2030 electricity from photovoltaic and wind power plants will even be cheaper than electricity from fossil fuel power plants. Small-scale rooftop PV plants in Northern Germany are producing clean electricity at costs lower than the average household electricity rate already today. Tomorrow's cheapest source of electricity will be the sun and wind.

[en] The electricity sector currently accounts for around 40 % of energy-related CO${}_2$ emissions in Germany. In order to reduce the remaining approximately 60 % CO${}_2$ emissions in the application areas of process heat, transport and building heat, a fundamental transformation of these areas is required. The study "Pathways to a Climate-Neutral Energy System" by the Fraunhofer Institute for Solar Energy Systems ISE examines possible transformation paths towards a climate-neutral energy system in the context of societal and individual behaviors. This article focuses in particular on the role of the electricity system in conjunction with sector coupling measures for the other sectors.

[en] This scenario analysis is the first to present concrete transformation pathways to climate neutrality in 2045 for Germany on the basis of a comprehensive model comparison. The special feature of this study by the Ariadne project is that six overall system and sector models (transport, heat transition, industrial transition, expansion of wind power and photovoltaics, hydrogen and e-fuels, flexibilisation through sector coupling) were integrated into one study, which complement each other in their respective strengths: For specific questions, the model that most accurately depicts the corresponding aspects was highlighted as the lead model in each case. Other models were used to analyse impacts of the transformation on environmental goods and the distribution of costs among different income groups. This broad approach makes it possible to describe the implications of the energy transition robustly and in detail.

[en] Highlights: • ICP is approached by the concept of eco-innovation. • Small firm size, perceived complexity and insufficient prices hinder effective ICP. • Qualitative content analysis was conducted for 18 semi-structured expert interviews. • The mainly quantitative ICP literature is complemented by qualitative research. • Policies for carbon leakage protection and corporate climate targets foster ICP. Internal Carbon Pricing (ICP) is a tool for companies to internalize negative external effects caused by their carbon emissions and to prepare themselves for a low-carbon economy. Globally, an increasing number of companies adopts ICP. Yet, many German firms do not use it yet. This paper explores why German companies do not adopt ICP and which barriers hinder the proper implementation of the instrument drawing on the concept of eco-innovation. Eighteen semi-structured interviews were conducted and analyzed using a structuring qualitative content analysis. The findings show that small companies face particularly strong challenges to mobilize the financial, technical, and informational resources necessary for the implementation of ICP. Internal carbon price levels similar to existing external carbon pricing schemes fail to unfold a steering function, because these prices are currently too low. Further difficulties arise due to the complexity of correctly accounting for GHG emissions and setting the right carbon price. The paper highlights the need for stringent external carbon policies on a national and European level, for more external information on ICP, and for the facilitation of cooperation between companies in order to increase the adoption rate and the efficacy of ICP in Germany.

[en] Highlights: • Flexibility from various processes of end-users can be deployed for own objectives and/or provide external services. • A MILP model is developed from common operational characteristics of processes and their components as a tool to evaluate end-users’ operational flexibility. • The model is used to optimize operations of a combined heat-and-power generation system and a steel production line consisting of interlinked processes. • Based on the developed model, flexibility potentials as external services and associated costs are also analysed. It is expected that end-users from all sectors should participate in providing system flexibility, as variable renewable energy is increasingly integrated into electricity systems. The ability of end-users to shift their electricity profiles has considerable potentials and can serve many purposes, e.g. to curb the peak load or to increase self-consumption. However, evaluation methods designed for flexibility from conventional power plants may be inadequate for flexibility from end-users due to the diverse constraints of underlying processes and limitations related to individual needs. This work presents a comprehensive and modular flexibility model developed from common operational characteristics of flexible processes as an alternativemethod. The model is applied to two examples: First, the operation of a combined heat-and-power plant including input and output storage is optimized with the objective to increase profits from electricity sales on the spot market. Second, a steel rod production line consisting of melting, casting, and milling processes is scheduled so that operating costs, including peak power costs, are minimized. Moreover, potentials of flexibility as external services and related costs are analysed. In this paper, the model is used to calculate the optimal costs (€), time-dependent flexibility potentials (kWh) and costs of flexibility provision (€/kWh). Thus, the adaptability and versatility of the model are demonstrated. As a modelling template, the model can ease the efforts of stakeholders in the characterization and evaluation of various flexible processes, especially those from small and medium-sized users.

[en] The dispatch opportunities provided by storage-enhanced Concentrating Solar Power (CSP) plants have direct implications on the investment decisions as not only nameplate capacity but also the storage capacity and the solar multiple play a crucial role for the viability of the plant investment. By integrating additional technical aspects and operation strategies, this paper extends the optimization model proposed by Madaeni et al., How Thermal Energy Storage Enhances the Economic Viability of Concentrating Solar Power. Using a mixed integer maximization approach the paper yields both the optimal layout decision and the operation of CSP plants. Subsequently, the economic value of CSP storage is analyzed via energy modeling of a Spanish plant location under the respective wholesale market prices as well as the local feed-in tariff. The analysis shows that investment incentives for CSP plants with storage need to appropriately account for the interdependency between the price incentives and the plant operating strategy. As the resulting revenue characteristics influence the optimal size of solar field and storage differing operating strategies also give rise to differing optimal plant layouts. Most noteworthy, the current Spanish support scheme offers only limited incentives for larger thermal storage capacity. - Highlights: • Dispatch opportunities of CSP have direct implications on both investment and operational decisions. • Valuation approach with a single mixed integer maximization problem. • Profitability of CSP plants under the premium feed-in tariff in Spain was assessed. • Layout decision and storage size are influenced by remuneration scheme. • Discuss alternative remuneration schemes for “dispatchable” RE technologies

[en] This paper discusses the value generation potential for local and international industry in different development scenarios of the concentrating solar power (CSP) market in North Africa until 2030. It analyzes the economic impact resulting from the participation of North African and European companies during construction and operation of CSP plants. The assessment is based on a self-developed solar technologies market development model (STMD) that includes economic and technical requirements and constraints for the creation of a local CSP market. In-depth interviews with industry stakeholders provide specific input, validate the calculations and complement the quantitative model results and conclusions. Long-term potential for locally generated revenues from CSP plant construction are modeled and lead to a share of local revenues of up to 60%. Potential market size of solar power plants in North Africa could reach total revenues of 120 Billion euros and thus demand for components and services contribute to national gross domestic products significantly. Recommendations are given for regional industry cooperation and policy actions for the support of local and international CSP industry in North Africa in order to improve the investment environment and growth of renewable energies in the region. - Highlights: ►New economic model to evaluate value generation of CSP take-off in North Africa. ►CSP components are assessed regarding their potentials to be produced locally. ►Potential for locally generated revenues of CSP plants: 60% of total value. ►Socio-economic impacts of RE projects become more relevant to investment decisions.

[en] The idea of generating electricity in North Africa using concentrating solar thermal power (CSP) has been around for some time now but has recently gained momentum through the Mediterranean Solar Plan (MSP) and the formation of the Desertec Industrial Initiative. This paper argues that while the large-scale deployment of CSP in North Africa does not seem economically attractive for either European or African institutions or countries on their own at present, combining domestic use and electricity exports could be profitable for both parties. A detailed economic portfolio covering both solar and wind power plants can achieve competitive price levels, which would accelerate the diffusion of solar technology in North Africa. This portfolio could be financed partially by exporting electricity from solar thermal plants in North Africa via HVDC interconnections to European consumers. Sharing the costs in this way makes it possible to generate solar electricity for the domestic market at a reasonable cost. Some of the electricity produced from the solar power plants and wind parks in North Africa is sold on European energy markets in the form of a long-term contracted solar-wind portfolio, which would qualify for support from the financial incentive schemes of the European Member States (e.g. feed-in tariffs). This transfer of green electricity could help to meet the targets for energy from renewable energy sources (RES) in the EU Member States as the new EU Directive of 2009 opened the European electricity market to imports from third states. - Research highlights: → This paper describes a feasible approach to financing a larger deployment of CSP in North Africa. → The proposed portfolio includes local consumption and electricity export to Europe. → Bundling wind with solar power as a business model for exporting solar electricity. → Prices of the solar-wind mix are competitive with other renewable energy sources. → Scenario outlook for the North African CSP market in six countries.