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The rapid fall in the cost of solar photovoltaics and wind energy offers a pathway to the deep decarbonization of energy at an affordable price. Off-river pumped hydro energy storage and batteries provide mature and large-scale storage to balance variable generation and demand while minimizing environmental and social impacts. High-voltage inter-regional interconnection and dispatchable capacity (existing hydro and geothermal) can help balance supply and demand. This work investigates an Indonesian energy decarbonization pathway using mostly solar photovoltaics. An hourly energy balance analysis using ten years of meteorological data was performed for a hypothetical solar-dominated Indonesian electricity system for the consumption of 3, 6 and 10 megawatt-hours (MWh) per capita per year (compared with current consumption of 1 MWh per capita per year). Pumped hydro provides overnight and longer storage. Strong interconnection between islands was found to be unnecessary for Indonesia, contrary to findings from similar modelling in countries at higher latitudes. Storage requirements for power and energy were found to be smaller than three kilowatts and 30–45 kilowatt-hours per person, respectively. Introducing gas turbines (burning hydrogen or synthetic methane) contributing around 1% of annual generation reduced the levelized cost of electricity (LCOE) by 14% and halved the storage requirements by allowing the system to ride through prolonged cloudy periods at lower cost. This work showed that Indonesia's vast solar potential combined with its vast capacity for off-river pumped hydro energy storage could readily achieve 100% renewable electricity at low cost. The LCOE for a balanced solar-dominated system in Indonesia was found to be in the range of 77–102 USD/megawatt-hour. [ABSTRACT FROM AUTHOR]

There are many promising renewable energy (RE) technologies that could help increase the contribution of RE in energy supply but which are not yet commercially available. The development rate of new RE technologies depends on many factors, such as Research and Development (R&D) efforts and policies. This study focuses on comparing China's efforts regarding the development of new RE technologies (e.g., wave and tidal, binary geothermal power, floating solar, micro hydro, osmotic energy, floating offshore wind and vertical axis wind turbines) with those of the European Union (EU). For this purpose, we collected data from publications and databases and analysed several indicators: e.g., the development of renewable electricity generation and capacity, demonstration projects, investments in R&D and patent applications. The results show that China has become a big player globally for mainstream renewable electricity (hydropower, wind and solar PV). This development is due to China's industrial policy and prioritization of effectiveness over cost efficiency. The main developments in China occurred in the 2010s, while the EU was a frontrunner in the 2000s. For the newer or less mainstream technologies, the application in China is still low, compared to the EU, except for floating solar, where China is a lead player. Regarding patent applications, China has shown a higher application amount compared to the EU since 2006. However, only a small share of China's patents are valid internationally. We conclude that China has emerged as a big player in mainstream renewable energy technologies over the last decade. In regard to new renewable energy technologies, China is predominantly involved in solar energy and, in comparison to the EU, less in other new technologies (e.g., binary geothermal systems and ocean energy). [ABSTRACT FROM AUTHOR]

Biogas produced by anaerobic digestion is an important renewable energy carrier. Nevertheless, the high CO 2 content in biogas limits its utilization to mainly heat and electricity generation. Upgrading biogas into biomethane broadens its potential as a vehicle fuel or substitute for natural gas. CO 2 -to-CH 4 bioconversion represents one cutting-edge solution for biogas upgrading. In situ bioconversion can capture endogenous CO 2 directly from the biogas reactor, is easy to operate, and provides an infrastructure for renewable electricity storage. Despite these advantages, several challenges need to be addressed to move in situ upgrading technologies closer to applications at scale. This opinion article reviews the state of the art of this technology and identifies some obstacles and opportunities of biological in-situ upgrading technologies for future development. Upgrading biogas into biomethane broadens its applications and increases the value of biogas. Among these, in situ CO 2 -to-CH 4 bioconversion can capture endogenous CO 2 directly from the biogas reactor, is easy to operate, and provides infrastructure for renewable electricity storage. Although promising, several intrinsic challenges need to be addressed to move in situ upgrading technologies closer to scaled-up application. In situ CO 2 -to-CH 4 bioconversion powered by renewable electricity could integrate multidisciplinary approaches including wind or solar energy technology, P2G technology, anaerobic digestion technology, and biogas upgrading technology. Bioelectrochemical systems are a potential technology for biogas upgrading and storing discontinuous wind/solar energy. However, their operating mechanism and scale-up feasibilities need to be further explored. [ABSTRACT FROM AUTHOR]

• A choice experiment was performed on third-party developers of RE projects in Sweden. • Wind and solar developers prioritize different stakeholder interests. • Wind developers prioritize the electricity output of projects. • Solar developers prioritize client satisfaction. • Intermediaries did not prioritize their own interests over their clients' interests. A transition towards a low-carbon energy system requires the large-scale diffusion of renewable electricity (RE) technologies. Intermediary actors, such as installers, project developers or consultants, can facilitate this process by supporting RE adopters. Recent studies have also pointed out that there are potential drawbacks associated with intermediary support. Acting as filters and gatekeepers, intermediaries have the complex mission to prioritize between various stakeholder interests, including their own profit maximization. The aim of this research is to understand what stakeholder interests intermediaries prioritize when developing RE projects. Results of a choice experiment with third-party developers in Sweden highlight differences between technologies: wind developers prioritize electricity output, while solar developers prioritize client satisfaction. Despite being for-profit organizations, intermediaries did not prioritize their own interests over the interests of their clients. Solar PV developers prioritize client satisfaction over maximization of electricity output, which may have negative implications for the efficiency of the projects. [ABSTRACT FROM AUTHOR]

Abstract To achieve China's 2030 goals for renewable energy development, this paper proposes a constrained fuzzy multi-objective optimization (FMO) model to obtain the optimal generation mix of four kinds of renewable power: hydropower, wind power, photovoltaic (PV) power, and biomass power. The optimization results show that a ) the optimal mix of accumulated installed capacity of renewable energy in China from 2017 to 2022 is hydropower > wind > PV > biomass, while that from 2023 to 2030 is PV > hydropower > wind > biomass; b ) the accumulated installed capacity of PV has the fastest growth between 2017 and 2030, and PV power will replace hydropower as the largest renewable power source in 2023. However, hydropower remains the largest renewable power through 2030 in terms of on-grid power generation; c ) these four kinds of renewable power generation can eliminate 34.9–37.5 billion tonnes of CO 2 emissions by replacing coal-fired power generation, with hydropower contributing the most to the reduction; and d ) Investment cost per kilowatt or the rate of power curtailment is not sensitive factor for optimal cumulative installed capacity. The results mean that China should promote PV power generation in a rapid but systematic manner while continuing to develop hydropower. Highlights • An FMO model for renewable energy generation mix is proposed. • Four kinds of renewable energy generation in China are optimized. • PV power will replace hydropower as the largest renewable power source in 2023. • Renewable power generation can reduce CO 2 emissions by 27.9–30.3 billion tons. [ABSTRACT FROM AUTHOR]

Abstract This work investigates a power dispatch system that aims to supply the power demand of the EU and Western Balkans (EUWB) based on low-carbon generation units, enabled by the expansion of biomass, solar, and wind based electricity. A spatially explicit techno-economic optimization tool simulates the EUWB power sector to explore the dispatch of new renewable electricity capacity on a EUWB scale, under ambitious CO 2 emission policies. The results show that utility-scale deployment of renewable electricity is feasible and can contribute about 9–39% of the total generation mix, for a carbon price range of 0–200 €/tCO 2 and with the existing capacities of the cross-border transmission network. Even without any explicit carbon incentive (carbon price of 0 €/tCO 2), more than 35% of the variable power in the most ambitious CO 2 mitigation scenario (carbon price of 200 €/tCO 2) would be economically feasible to deploy. Spatial assessment of bio-electricity potential (based on forest and agriculture feedstock) showed limited presence in the optimal generation mix (0–6%), marginalizing its effect as baseload. Expansion of the existing cross-border transmission capacities helps even out the variability of solar and wind technologies, but may also result in lower installed RE capacity in favor of state-of-the-art natural gas with relatively low sensitivity to increasing carbon taxes. A sensitivity analysis of the investment cost, even under a low-investment scenario and at the high end of the CO 2 price range, showed natural gas remains at around 11% of the total generation, emphasizing how costly it would be to achieve the final percentages toward a 100% renewable system. Highlights • A case study on decarbonizing the EU and Western Balkans power sector is performed. • As cost of variable renewables drops, decarbonization proceed regardless of CO 2 policies. • Sensitivity analysis about the impact of cross-border transmission capacity expansion. • Final percentages toward a 100% renewable electricity likely to be costly to achieve. [ABSTRACT FROM AUTHOR]

Meeting energy needs and ensuring ecological sustainability are important tasks for policymakers. In particular, changing the energy mix used in daily electricity generation can have a major effect on ecological conditions, and this is a previously neglected research topic. Therefore, this paper aims to investigate the influence of daily electricity generation from nuclear power and renewables on the achievement of carbon neutrality targets in the four largest nuclear power countries (i.e., the U.S., China, France, and Russia). The study applies the wavelet-transform coherence (WTC), quantile-on-quantile regression (QQR), and Granger causality in quantiles (GCQ) approaches for the period from January 2, 2019 to December 29, 2022. The outcomes present that electricity generation from nuclear energy reduces carbon (CO 2) emissions only in Russia, while hydropower generation does not contribute to CO 2 emission reduction in any country. Solar electricity generation decreases CO 2 emissions in different quantiles in the U.S. and Russia, while electricity generation from wind power reduces CO 2 emissions in the U.S. and France. The empirical outcomes also reveal that expanding solar, wind, and nuclear power in the energy mix can enhance the potential of the U.S., France, and Russia to achieve carbon neutrality and secure a sustainable future. However, China is using nuclear and renewables inefficiently regarding carbon neutrality. Therefore, the empirical evidence for China is highly controversial compared to former studies. [Display omitted] • The study examines renewable and nuclear electricity effect on carbon neutrality. • The study focuses on top four major nuclear power countries. • The study applies nonlinear approaches by using high-frequency (daily) data. • Renewable and nuclear electricity have time, frequency, & quantile-varying effect. • The best electricity source change according to each country. [ABSTRACT FROM AUTHOR]

The rapid growth of renewable energy (RE) is disrupting and transforming the global energy system, especially the electricity industry. As a result, supporters of the politically powerful incumbent industries and others are critiquing the feasibility of large-scale electricity generating systems based predominantly on RE. Part of this opposition is manifest in the publication of incorrect myths about renewable electricity (RElec) in scholarly journals, popular articles, media, websites, blogs and statements by politicians. The aim of the present article is to use current scientific and engineering theory and practice to refute the principal myths. It does this by showing that large-scale electricity systems that are 100% renewable (100RElec), including those whose renewable sources are predominantly variable (e.g. wind and solar PV), can be readily designed to meet the key requirements of reliability, security and affordability. It also argues that transition to 100RElec could occur much more rapidly than suggested by historical energy transitions. It finds that the main critiques published in scholarly articles and books contain factual errors, questionable assumptions, important omissions, internal inconsistencies, exaggerations of limitations and irrelevant arguments. Some widely publicised critiques select criteria that are inappropriate and/or irrelevant to the assessment of energy technologies, ignore studies whose results contradict arguments in the critiques, and fail to assess the sum total of knowledge provided collectively by the published studies on 100RElec, but instead demand that each individual study address all the critiques’ inappropriate criteria. We find that the principal barriers to 100RElec are neither technological nor economic, but instead are primarily political, institutional and cultural. [ABSTRACT FROM AUTHOR]

This study investigates the production of green hydrogen for use in oil refining, as specified in the draft of European union delegated act published in May 2022. The European union plans to set strict requirements of additionality and reporting regarding the criteria of renewable electricity used in hydrogen production. Alkaline electrolyzer, proton exchange membrane electrolyzer and solid oxide electrolyzer are evaluated in various scenarios supplied by wind power: power purchase agreement-based scenarios and wind power investment-based scenarios. In power purchase agreement-based scenarios baseload and pay as produced power purchase agreements (with and without electricity storage) are assessed. According to results, the use of 600 MW compressed air energy storage could reduce the dependency on the grid by 7% but increase the cost of green hydrogen significantly. Investment-based scenarios produce green hydrogen with a lower operation cost, but higher break-even price compared to power purchase agreement-based scenarios. The cheapest green hydrogen can be achieved by alkaline electrolyzer with baseload power purchase agreement. Direct ownership of wind power is outside the operation of oil refining industry, thus power purchase agreements contracting is more likely to realize. [Display omitted] • Green hydrogen production for industry with EU proposed rules is studied. • EU proposed rules drive renewable electricity investments to suboptimal sites. • PPA agreements for wind power will probably be used by industry. • Hydrogen break-even price is found to be 4–7 €/kgH 2 in the Finnish case. [ABSTRACT FROM AUTHOR]

Rapid decarbonisation of electricity production is required if Australia is to meet its obligations under the Paris Agreement. Critical to achieving this at low cost while maintaining system reliability is the selection of an appropriate mix of generation technologies to service electrical demand. Australia has seen extensive deployment of renewable energy technologies such as onshore wind and solar but has not yet seen the adoption of offshore wind technology. However, there is currently significant interest in developing this resource, with ongoing debate occurring about future technology costs and the potential of onshore renewables to meet electrical demand. This article presents the results of an investigation into the techno-economic impact of exogenously fixing offshore wind capacity on a future least-cost Australian National Electricity Market with 100 % renewable generation. An existing open-source cost optimisation model, National Electricity Market Optimiser, was used for the study. It was found that increasing the capacity of offshore wind in the generation mix leads to displacement of both onshore wind and solar generators. This is due to the greater magnitude and consistency of the offshore wind resource relative to onshore. Increasing offshore wind capacity therefore tends to reduce the total system generation capacity, as well as the amount of unused surplus generation. Using lowest published projections for future capital costs, inclusion of offshore wind was found to reduce total system costs. Using an average of future cost projections, total system costs were found to increase. However, adding up to 15 GW of offshore wind capacity to a 100 % renewable system would only impact total system costs by 5 %. Given the other potential advantages of offshore wind, namely closer siting to load centres, reduced need for onshore land resources, and the potential to transition existing fossil fuel workers, our results suggest that offshore wind may be a suitable candidate for inclusion in Australia's transition to a low carbon electricity system, under a range of future cost scenarios. • Inclusion of offshore wind reduces system costs under low cost scenario. • Inclusion of offshore wind increases system costs under average cost scenario. • Offshore wind can be added without large cost increases under average cost scenario. [ABSTRACT FROM AUTHOR]

Taiwan's feed-in tariff (FIT) policy, revised in 2009, sets a goal to increase the installation capacity 6,500-10,000 MW (megawatts) of renewable power systems in 20 years. The purpose of this paper is to examine whether the goal can be achieved or not. This paper presents an overview of FIT policies implemented in some leading countries and their performance of renewable electricity installed capacity and generation. This paper presents two outlook scenarios for Taiwan's renewable power installation capacity by using Germany as a benchmark after a detailed analysis and discussion on Taiwan's historical evolution of renewable energies. The Moderate Scenario projects that total cumulative capacity of renewable power systems increases from 5,813.8 MW in 2010 to 7,245.99 MW in 2030, while the Optimistic Scenario estimates the total renewable power capacity will be 11,977.14 MW in 2030. The total increase in the new installation capacity attain to 1,432.19 and 6,163.64 MW for the two scenarios, respectively. [ABSTRACT FROM AUTHOR]

When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times more health and environmental benefits. A wind turbine in West Virginia displaces twice as much carbon dioxide as the same turbine in California. Depending on location, we estimate that the combined health, environmental, and climate benefits from wind or solar range from $10/MWh to $100/MWh, and the sites with the highest energy output do not yield the greatest social benefits in many cases. We estimate that the social benefits from existing wind farms are roughly 60% higher than the cost of the Production Tax Credit, an important federal subsidy for wind energy. However, that same investment could achieve greater health, environmental, and climate benefits if it were differentiated by region. [ABSTRACT FROM AUTHOR]

Abstract: The intensity of market penetration and hence the relevance of clean energy technologies in mitigating climate change will greatly depend on their cost-effectiveness. This paper discusses the economic and policy aspects of speeding up the market of these technologies to reach cost parity. A combination of historical energy market dynamics, technology diffusion and endogenous learning models were employed in the analyses. Starting from giving a preferential position to emerging renewable energy technologies in the energy and climate policy, which also means securing adequate financial resources for their deployment, could lead in the base scenario to a full-cost breakthrough of wind power around 2027 and of photovoltaics in 2032. The combined global market share of renewable electricity in 2050 could reach 62% of all electricity (now 19%) of which wind and solar power alone could account for almost two-thirds corresponding to a carbon saving in the range of 8–16 GtCO2. However, if the new technologies were downgraded in the energy and climate policy context, the combined impact of solar and wind could remain at no less than 11% which would marginalize these technologies in the fight against climate change. The estimates for financial support to achieve cost parity were very sensitive to the assumptions of the input parameters: in the base case the extra costs or learning investments for solar power were €1432 billion and for wind power €327 billion, but with more conservative input data these values could grow manifold. On the other hand, considering the potentially cheaper electricity from new technologies above the cost parity point and putting a price on carbon could result in a positive yield from public support instead of it being regarded merely as unnecessary spending. The findings stress the necessity of long-term policies and strong commercialization strategies to bring the new energy technologies to breakeven point, but also highlight the complexity of assessing the true costs of making new energy technologies fully competitive. [Copyright &y& Elsevier]

Abstract: In Ontario (Canada), the integration of renewable power is a priority policy goal. Since 2004, the circumstances under which the integration of renewable power is evaluated have changed due to successive changes in price as well as concerns that its over-production may add to grid congestion. This research investigates the value of increasing complementarity (both proximate and geographically dispersed) of wind and solar resources as a means by which electricity planners and researchers might advance electricity sustainability in Ontario. More specifically, this paper asks the following questions: 1) Does the combination of solar and wind resources in selected locations in Ontario serve to ‘smooth out’ power production, i.e., decrease instances of both high and low values, as compared to either resource producing individually? 2) Can this ‘smoothness’ be further improved by dispersing these resources geographically amongst locations? and 3) Does increasing the number of locations with solar and wind resources further ‘smooth out’ power production? Three years (2003–2005) of synchronous, hourly measurements of solar irradiance and wind speeds from Environment Canada’s Canadian Weather Energy and Engineering Data Sets (CWEEDS) are used to derive dimensionless indices for four locations in Ontario (Toronto, Wiarton, Sault Ste. Marie and Ottawa). These indices are used to develop three transparent and accessible methods of analysis: (1) graphical representation; (2) percentile ranking; and (3) using a theoretical maximum as a proxy for capacity. The article concludes that the combination of solar and wind within locations and amongst two locations improves ‘smoothness’ in power production, as compared to when each resource is produced on its own; moreover, it is further improved once more than two resources and two locations are combined. However, there is neither further benefit, nor drawback, associated with the geographic dispersion of complementarity between solar in one location and wind in another, when compared to both resources in one location. [Copyright &y& Elsevier]

Abstract: In Great Britain, electricity is traded in an energy-only market that relies upon bilateral trading until shortly before real time. The GB System Operator also uses bilateral trading to respond to changes in demand and generation and resolve transmission constraints. Prices are not explicitly spatial, although well-placed generators can charge the system operator more for their output. This paper argues that these arrangements are not well-suited for the challenges of accommodating nearly thirty percent of intermittent wind generation, often located far from demand. The market design already implemented in the north-eastern United States is likely to be more efficient. [ABSTRACT FROM AUTHOR]

Abstract: Main electrical energy sources of Turkey are thermal and hydraulic. Most of the thermal sources are derived from natural gas. Turkey imports natural gas; therefore, decreasing usage of natural gas is very important for both economical and environmental aspects. Because of disadvantages of fossil fuels, renewable energy sources are getting importance for sustainable energy development and environmental protection. Among the renewable sources, Turkey has very high wind energy potential. The estimated wind power capacity of Turkey is about 83,000MW while only 10,000MW of it seems to be economically feasible to use. Start 2009, the total installed wind power capacity of Turkey was only 4.3% of its total economical wind power potential (433MW). However, the strong development of wind energy in Turkey is expected to continue in the coming years. In this study, Turkey''s installed electric power capacity, electric energy production is investigated and also Turkey current wind energy status is examined. [Copyright &y& Elsevier]

Abstract: The overall objective of this paper is to analyze the impact of climate policy and technology learning on future investments in the Swedish power sector. Methodologically we assess the lifetime engineering costs of different power generation technologies in Sweden, and analyze the impact of carbon pricing on the competitive cost position of these technologies under varying rate-of-return requirements. We also argue that technological learning in the Swedish power sector – not the least in the case of wind power – is strongly related to the presence of international learning and R&D spillovers, and for this reason capacity expansions abroad have important influences of the future cost of power generation in Sweden. The results suggest that renewable power will benefit from existing EU climate policy measures, but overall additional policy instruments (e.g., green certificate schemes) are also needed to stimulate the diffusion of renewable power. Moreover, under a recent European Commission scenario and using estimated learning rates for wind power and the combined cycle gas turbine (CCGT), wind power gains considerable competitive ground due to international technology learning impacts. These latter results are, however, very sensitive to the assumed learning-by-doing rates for wind power and CCGT, respectively. [Copyright &y& Elsevier]

• Hybrid DBD plasma reactor process design was performed. • Integration of plasma reactor into a conventional SMR process was performed. • Electricity cost of <$0.004/kWh needed for plasma process to be competitive. • Environmental impacts of plasma reactor process were higher than SMR. • Wind electricity use improved plasma design environmental impacts. Utilization of electricity generated from renewable sources to obtain hydrogen, H 2 , is of critical importance to decrease the overall carbon footprint. In this work, integration of a dielectric discharge barrier (DBD) plasma reactor to convert low calorific value gas, such as landfill gas or coal mine gas into hydrogen, into the existing steam methane reforming (SMR) technology was evaluated using process design considerations. In particular, a DBD-enhanced catalytic SMR reactor was modeled to operate at near atmospheric pressure and 500 °C sequentially with the conventional reformer to obtain ~ 65 kmol/hr H 2 for distributed production. This allowed decreasing the size of the conventional reformer albeit at the increased overall electricity consumption. Calculated process economics showed that only at an electricity cost of less than $0.004/kWh does the hybrid DBD plasma process derived H 2 price become competitive with that of the conventional SMR. A Life Cycle Assessment framework was used to compare environmental impacts from the conventional SMR, hybrid DBD SMR and hybrid DBD SMR utilizing only onshore wind-derived electricity. Larger environmental impacts in the plasma reformer were obtained due to the use of electricity for the plasma reforming operation, which was modeled as coming from the typical U.S. grid mix. Utilizing only 100% wind-derived electricity provided certain environmental benefits, except for the ecotoxicity impact where the wind power scenario modeled here only reduced ecotoxicity impacts associated with electricity by 30%. [ABSTRACT FROM AUTHOR]

The Irish Government recently unveiled plans to have 70% of electricity in the state generated from renewable energy sources by 2030. Currently very little electricity is generated by solar photovoltaic in Ireland. In this study, a real options framework is applied to assess the economic feasibility of utility-scale solar in Ireland. Initially, electricity prices are identified as the main source of uncertainty and the Least Square Monte Carlo method is used to price the real option. The findings are that, in the absence of comprehensive policy support, large-scale investment in solar in Ireland is not commercially viable and that, where the real option has value, the optimal strategy is to defer investment. Sensitivity analysis shows that the results are robust and the analysis allows investors to make an informed bid to the newly introduced Renewable Electricity Support Scheme (RESS). When policy support is introduced, a large real option value is obtained, and utility scale solar investment is profitable. The implications are that solar-specific policy supports may work better than policies that include all renewable technologies because the dominance of onshore wind energy in Ireland may price other renewable sources out. • Real options is a superior approach when evaluating renewable energy investments. • Evaluation of a utility-scale solar photovoltaic project in Ireland. • Technology-specific policy supports will foster investments in solar. [ABSTRACT FROM AUTHOR]

In this paper, we investigate capacity expansion, the technological development of wind turbine generators, and the merits of onshore wind repowering in Germany. We analyze the regulatory framework that is presently in place and its impact on the profitability of the onshore wind parks commissioned under previous regulatory frameworks. The optimal timing of repowering under today's market premium model is scrutinized. Repowering in a market without subsidies for onshore wind energy is also evaluated. In the two cases (regimes) investigated, the electricity price is modeled stochastically as a geometric Brownian motion process. More specifically, using a real options modeling framework for investments under a free market regime, we analyze how the regime change affects the optimal timing of repowering. Further, we check the results for their robustness via a sensitivity analysis for both analyzed regimes. We find that repowering well before the plant's expected end of life ('early repowering') can be economically preferable under the German Renewable Energy Sources Act 2017 remuneration scheme and that, due to the electricity spot market price development, repowering under the market premium regime is more profitable than it is under the free market regime. The economic viability is strongly influenced by the duration of the initial tariff granted to the old installation, the expected digression factor of the future reference tariff, and the increase in electricity generation achieved through repowering. [ABSTRACT FROM AUTHOR]