Renewable Generation Capacity Research Articles

Development Scenarios and Environmental Benefits Analysis of Future Power Generation Industry Under Two Modes in China

In order to study the impact of the "carbon peak and neutrality" mode on future power generation and the environment in China, a Verhulst gray model was established to predict the development of the power generation industry from 2021 to 2060 under the non-"carbon peak and neutrality" mode. In addition, based on the "China 2030 Energy and Power Development Planning Research and 2060 Outlook Report," the development of the power generation industry from 2021 to 2060 under the "carbon peak and neutrality" mode was obtained, and the development scenarios of the future power generation industry in China under two models were compared and studied. The emission factors and emission reduction factors of CO2, SO2, NOx, PM, PM10, and PM2.5 were constructed through the conservation of elements and the generating performance standard, and then four environmental benefits A1-A4 were defined. The results showed that the installed capacity of thermal power will reach the carbon peak in 2026 under the "carbon peak and neutrality" mode. To achieve the carbon neutralization, the installed capacity of thermal power will be reduced by an average of 28 million kilowatts per year after 2026, and the installed capacity of renewable energy generated is required to increase by 154 million kilowatts per year after 2020. Compared with that in the non-"carbon peak and neutrality" mode, the installed capacity of thermal power generation will be greatly reduced, and the installed capacity of renewable energy power generation will be greatly increased under the "carbon peak and neutrality" mode, resulting in huge A1 and A2 environmental benefits. In the next four decades, the cumulative emission reductions in CO2, SO2, NOx, PM, PM10, and PM2.5 thermal power generation A1 are predicted to be 6.64×1010 tons, 1.54×107 tons, 1.55×107 tons, 3.18×106 tons, 1.71×106tons, and 2.23×105 tons, respectively. The cumulative emission reductions of renewable energy power generation A2 will be 5.77×1010 tons, 1.64×107 tons, 1.42×107 tons, 2.86×106 tons, 1.54×106 tons, and 2×105 t tons, respectively. Under the "carbon peak and neutrality" mode, compared with those from coal-fired power generation, the environmental benefits A3 and A4 produced by the relative cleanliness of renewable energy and nuclear power indicated that the cumulative emission reductions (A3+A4) in clean energy power generation of CO2, SO2, NOx, PM, PM10, and PM2.5 in the next four decades will be 3.014×1011 tons, 7.292×107 tons, 7.119×107 tons, 1.454×107 tons, 7.827×106tons, and 1.018×106 tons, respectively.

ПОТЕНЦИАЛ ТЕХНОЛОГИЙ ВОЗОБНОВЛЯЕМЫХ ИСТОЧНИКОВ ЭНЕРГИИ В УСЛОВИЯХ СИБИРИ

The use of both main and alternative energy sources to ensure energy security is considered. The incentives for the development of renewable energy in the conditions of Siberia have been determined. The analysis of the potential for the use of cogeneration plants, small hydropower facilities, solar energy, wind energy, the use of low-grade heat and bioenergy has been carried out. The prerequisites for increasing the capacity of renewable energy generation are determined

Evaluation of levelized cost of hydrogen produced by wind electrolysis: Argentine and Italian production scenarios

Green hydrogen will play a key role in the future energy transition to achieve the main decarbonization goals. However, many large economies have limited renewable energy generation capacity, which leads to the identification of strategic sites for the global export of hydrogen. The aim of this work is to investigate the techno-economic feasibility of green hydrogen production in Argentine Patagonia with subsequent ship transport to Italy. The study includes the entire supply chain, from the production of hydrogen with renewable energy sources to its final use as a fuel for mobility in Italy. Different scenarios have been identified and compared, considering that the hydrogen production can take place directly in Italy or in Patagonia, followed by a transport to Italy. It was assumed that hydrogen is produced through PEM electrolyzers powered by wind energy. Various hydrogen transport and storage methods were analyzed to assess which is the most cost-effective solution. In addition, the influence of wind capacity factor and electricity cost on the levelized cost of hydrogen (LCOH) was analyzed to provide an in-depth comparative assessment of the two production scenarios. Even considering the additional transport costs from Argentina to Italy, the scenario with hydrogen production in Patagonia was found to be more convenient than the production in Italy. This is due to the high wind potential in Patagonia, where the average wind capacity factor is about 50% compared to 25% in Italy. The minimum LCOH was obtained considering the storage and transport of hydrogen by means of liquid organic hydrogen carriers, with a final cost of 8.60 €/kgH2 and 11.17 €/kgH2 for the Argentine and Italian production scenarios, respectively. The results of the complete supply chains were analyzed step by step, and the reasons behind the most competitive option elucidated in detail.

Aggregate load profile and decarbonization: Impacts of actionable demand drivers in New York

In a decarbonized future, electricity will likely play a much greater role in all aspects of the economy, while power generation will increasingly rely on intermittent sources such as wind and solar. In deep decarbonization studies of power systems, the most striking conclusions are usually on the generation side: the need of tens of GW of new clean generation capacities and storage are typical conclusions. However, these conclusions are the direct consequence of electricity demand projections, which usually get less attention and sometimes lack detailed explanation. At the very least, these projections are aggregated and suffer from a deficit of transparency in their methodology. A detailed knowledge of possible future load profiles, and how the evolution of their drivers influences their shape, is therefore very important to plan adequately energy and power requirements, as well as regional interconnections and storage. This paper uses a bottom-up approach based on the useful energy consumed in the residential, commercial, transportation and industrial sectors to explore the load profile sensitivity to key parameters. This approach is then used to provide hourly load profiles for a full year for the state of New York as an illustration. The impact of these key parameters is demonstrated through three scenarios: business as usual, accelerated electrification and energy efficiency breakthrough. Policy makers, planning for very ambitious penetration level of renewable energy generation capacity have to take into account the effect on electricity peak and total demand of their energy efficiency initiatives.

Modeling the Baltic countries’ Green Transition and Desynchronization from the Russian Electricity Grid

In the next ten years, the Baltic countries ― Estonia, Latvia, and Lithuania ― are planning large investments in renewable power generation and transfer capacity, substantial phase-out of fossil-based power generation, and desynchronization from the Russian electricity grid. In this article, the operational impacts of these changes on the Baltic energy system from 2017 to 2030 are studied with an open-source Backbone energy system model. The operation of Estonian, Latvian and Lithuanian power and heat, transport, and building sectors are optimized simultaneously on an hourly level, and results are analysed with operational, environmental, economic, and security indicators. Results suggest that the planned transition would support Baltic targets in renewable generation (from 45% to 92%) and self-reliance (2.3 TWh increase in domestic power generation and 5.5 TWh decrease in natural gas imports) with a moderate impact on system costs. However, an increase in transport CO2 emissions could risk national non-ETS targets. The hourly operation of the system, with a high share of wind and solar, is based on active use of storages and interconnectors. Model results raise concerns about the amount of Estonian dispatchable capacity, the commercial feasibility of Latvian natural gas CHP’s, and the high ramping rates of Lithuanian interconnectors.

Carrying Capacity of Water Resources for Renewable Energy Development in Arid Regions in Northwest China: A Case Study of Golmud, Qinghai

Abstract: Northwest China has become a base for wind and solar energy development due to its rich wind and solar resources and large area of desert and unutilized land. However, whether the scarce water resources in the arid regions there can meet the requirements for renewable energy development is currently a pressing, critical problem. Therefore, the life cycle water footprint (WF) of the renewable energy industry—its wind energy, photovoltaic (PV), and concentrated solar power (CSP) electricity generation enterprises—in the basin area of Golmud, Qinghai, a typical arid region in Northwest China, has been investigated in this study. Water consumption by local renewable energy enterprises was estimated under current (2020) scenarios [i.e., different (local/vs. nonlocal) origins of equipment and raw materials used, and employees hired by these enterprises] and three future scenarios (i.e., different ratios between installed capacities of wind energy, PV, and CSP at a fixed total renewable energy electricity generation capacity assuming China’s carbon emission will peak then). The results revealed that water consumption by local renewable energy enterprises in 2020 was 1.62 × 106–1.31 × 107 m3, accounting for 0.07–0.6% of the current total water resources in the basin area of Golmud. Water consumption by the local salt chemistry industry, a pillar industry in Golmud whose water consumption is high, accounted for 2.69% of the total water resources being 4.24–34.37 times that of the local renewable energy industry. To reach the goal of carbon emissions peaking by 2030 requires an increase of 6.17 × 106 kW in the installed capacity for wind and solar power generation in Golmud, would translate into an increase of 1.57 × 107–6.46 × 107 m3 in water consumption, this accounting for 7.15–19.35% of the remaining available water resources in the basin area of Golmud. Our results indicate that the expansion of the local renewable energy industry has exerted significant pressure on the already scarce water resources in Golmud. Therefore, future increases in the installed capacity for renewable energy electricity generation should be planned scientifically, by considering the availability of water resources as a constraint.

Quantifying the effects of forecast uncertainty on the role of different battery technologies in grid-connected solar photovoltaic/wind/micro-hydro micro-grids: An optimal planning study

Designing a reliable and robust micro-grid (MG) aided by energy storage devices requires quantifying the parametric uncertainty associated with input data time-series, among other types of uncertainties – and in particular, the uncertainty in forecasted meteorological, load demand, and wholesale electricity price time-series. Given the computational complexities involved, the recent battery-storage-supported MG capacity optimisation literature fails to simultaneously characterise multiple sources of data uncertainty. This paper, therefore, seeks to address this knowledge gap by hedging against a wide array of parametric uncertainties at the same time, whilst exploring the potentially salient implications of high-dimensional uncertainty characterisation for the costing and configuration of battery-supported, grid-tied MGs. To this end, this paper introduces a novel computationally efficient, stochastic MG design optimisation model that enables the simultaneous handling of multiple uncertain inputs. Notably, the model yields in-depth, accurate, and robust infrastructure decision-making support, particularly with regard to the optimal size of battery storage, by specifically analysing the worst-case, most likely case, and best-case uncertainty characterisation scenarios. To demonstrate the effectiveness of the model within a community renewable energy project scheme, a case study of a grid-connected, battery-storage-supported MG in the town of Ohakune, New Zealand is presented. Importantly, the numerical simulation results indicate that the life-cycle cost of the MG would have been underestimated by as much as ~8% (equating to NZ$0.3 m) in the most likely case – with an associated ~15% (equating to 143 kWh) battery size underestimation – if the variability inherent in forecast inputs was not factored into the analysis. Also, the proportion of the energy storage capacity to the total renewable power generation capacity is ~71%, ~76%, and ~68% in the best-case, most likely case, and worst-case scenarios, respectively, suggesting that the risk-seeking and risk-averse MG planning strategies have a slightly contradictory effect on the storage-to-generation ratio. Comprehensive sensitivity analyses of different battery technologies with different specific power, specific energy, and depth-of-discharge specifications have also demonstrated the robustness and validity of the model, whilst additionally identifying the sodium‑sulfur (NaS) battery technology as the most profitable choice in grid-connected MG development applications – which can be primarily attributed to the fact that it provides the best trade-off between the specific power and specific energy.

Impact on the power mix and economy of Japan under a 2050 carbon-neutral scenario: Analysis using the E3ME macro-econometric model

ABSTRACT This study uses the E3ME macro-econometric model to simulate what Japan’s macroeconomy would look like and how Japan's energy composition would change if the country were to achieve carbon neutrality by 2050. The results indicate that renewable energy will account for about 90% of the power supply configuration in 2050, assuming nuclear power plants are phased out by 2040. It is also predicted that GDP will increase by 4.0%–4.5% compared with the baseline scenario and that employment will improve by 1.5%–2.0%, resulting in simultaneous achievement of carbon neutrality and economic growth. The main reasons for these projected outcomes are that increased investment in renewable generation capacity in the power sector would be accompanied by increased investment in decarbonization technologies across individual economic sectors, increased private consumption resulting from increased employment and energy efficiency savings, and an improvement in the trade balance due to a substantial reduction in fossil fuel imports. In addition, the costs of energy due to policies to reduce or eliminate carbon would rise by 45%–55% point at most above the baseline scenario even in 2050; however, this would be of little burden on the economy, considering the substantial reduction in fossil fuel energy demand. Overall, it is estimated that energy bills would be 45% lower for consumers and 11% lower for industry in 2050 compared with the baseline. Key policy insights The study shows that achieving climate neutrality does not require difficult trade-offs with economic growth. Instead, it can provide economic opportunities that arise from switching to renewables and decarbonization technologies. The rapid reduction in global renewable costs for wind and solar technologies means that the net zero transition does not have to rely on relatively more expensive nuclear power. The true costs of nuclear could be a lot higher when the costs of safety regulations are properly accounted for. Instead, investment in electricity storage should be prioritized. A well balanced decarbonization policy mix for each sector is required. Policy makers should not rely on carbon pricing instruments alone. Supporting policies such as R&D spending, renewable subsidies, regulations and energy demand reduction should also be considered.

A Multiobjective Optimization Approach for Retrofitting Decision-Making towards Achieving Net-Zero Energy Districts: A Numerical Case Study in a Tropical Climate

Buildings are among the main reasons for the deterioration of the world environment as they are responsible for a large percentage of CO2 emissions related to energy. For this reason, it is necessary to find solutions to this problem. This research project consists of constructing the metamodel of an urbanization located in Panama, Herrera province. The classification and systematization of its main elements, using the software DesignBuilder and SysML diagrams, were carried out for its subsequent implementation in an optimization analysis that seeks to approach the NZED standard. The main objectives of the optimization are reducing the energy consumption at the lowest possible price while maintaining or improving thermal comfort. In this study, it was possible to reduce electricity consumption to at least 60% of the original value and about 10% of the renewable energy generation capacity by implementing optimization techniques within the retrofit category related to the envelope of the buildings and the occupant’s behavior.

Comparing open source power system models - A case study focusing on fundamental modeling parameters for the German energy transition

Recent European and German climate targets call for a faster power system transition towards variable renewable energy sources. With the increasing importance of Open Science, several Open Source models have been developed in recent years. However, only a few studies exist that compare their performance against each other. Therefore, this study performs a comprehensive model comparison of five mature Open Source power sector models. For this purpose, we apply eight fully harmonized and simplified one-year scenarios for the German power sector, to analyze deviations in model results. First, an in-depth analysis of two base scenarios for 2016 and 2030 reveals that linear programming-based models differ substantially from models with pre-implemented dispatch orders. Other deviations occur across all models and are mainly caused by the indifferent use of flexibility options such as storage and transmission. Second, variations of parameters and characteristics with a political significance are individually applied to the 2030 base scenario to identify their impact on model results. This includes CO2 emission budgets, increased demands by sector coupling, coal exit strategies, and renewable generation shares. The results prove that some models are far more sensitive to these parameters than others, and renewable generation shares alone are not sufficient to reach desired effects in emission reductions. Finally, a comprehensive scenario for 2030 combines all measures to evaluate general trends that result from the most recent updates in German energy policy. Model results indicate that the new targets require substantially increased investments into renewable generation capacities, storage, and transmission.

Transient stability and FRT technologies of different synchronous wind turbine

With the global energy transformation towards to a 100% renewable-based power system, the installed capacity of renewable energy generation has continued to grow rapidly in recent years. At the same time, due to the loss of synchronous machines, the grid-connected large-scale renewable energy bring great challenges to the safe and stable operation of power grid. In order to improve the stability of power grid, different synchronous wind turbine have widely attracted the attention of academia and industry. That is totally different on transient stability of vector synchronous wind turbine and self-synchronous wind turbine, and the fault ride through (FRT) control strategy is also different. Thus, the transient stability and FRT technologies of vector synchronous wind turbine and self-synchronous wind turbine are studied separately. There are many solutions for the FRT of vector synchronous wind turbine from different technical schemes. According to the different scope of application and implementation methods, it can be roughly divided into two categories: software improvement and hardware addition. Different FRT strategy of self-synchronous wind turbine are used under a smaller grid fault and serious grid fault, self-synchronous wind turbine recalculate the voltage and phase angle of the potential in the converter according to the PCC voltage, PCC phase angle, reactive power demand and residual active capacity under a smaller grid fault. When there is serious grid fault, the vector control and self-synchronous control modes switching FRT strategy is necessary.

Financiers' perceptions of risk in relation to large hydropower projects

Abstract More renewable electricity generation capacity will be needed to support progress towards Sustainable Development Goals and the Paris Agreement objective in lower income and lower-middle income countries (LICs and L-MICs). In the context of declining availability of public sector finance for energy generation, there is a widespread expectation that much of the new generation capacity will need to be financed entirely by the private sector or through public-private-partnerships (PPPs). Sustainably developed large hydropower could play a vital role in a future electricity mix dominated by intermittent renewables. In addition to generating low-cost, low-carbon electricity at a large scale, hydropower is capable of delivering ancillary services that are needed to facilitate greater penetration of intermittent renewable electricity. However, concerns over social and environmental outcomes, uncertain financial returns and thus a widespread perception of large hydropower as a ‘high risk’ investment has so far made it difficult to attract private sector investment for such projects, especially in many LICs and L-MICs. This paper addresses the gap in the existing knowledge base by developing a conceptual analytical framework for public and private sector actors. The framework provides a structured approach to the analysis of risk which can aid governments, developers, lenders and investors in maximising the likelihood of a project obtaining sustainable finance. The findings suggest that many of the greatest risks associated with large PPP hydropower projects in LICs and L-MICs are those that can cause reputational damage to the involved parties, such as social and environmental risks. The results presented in this paper will enable governments and developers to take targeted action to reduce risk and thus facilitate more effective use of the PPP financing model for large renewable energy infrastructure projects in LICs and L-MICs where additional large-scale sustainable electricity generation capacity is most needed.

Hydropower development, policy and partnership in the 21st century: A China-Nigeria outlook

Regardless of the challenges facing renewable energy development in today’s world, hydropower is still the most broadly patronized source of renewable energy, with a global installed capacity of 1330 GW in 2020. Hydropower contributes the largest share of the total installed renewable energy globally, accounting for more than 54% of renewable energy generation capacity worldwide. In this 21st century, the quest for a global shift to a carbon-emission-free future has been epitomized by China through its way of overcoming some crucial challenges to becoming the number one hydropower producer in the world. China is currently the top exporter of its hydropower technology and expertise to a reasonably significant number of countries across the globe. Due to failed energy policy implementation, Nigeria, on the other hand, has been languishing in air pollution from fossil fuel energy generation due to poor and erratic electrical energy supply from the grid, despite its enormous hydropower potential. However, a resurgence of Nigeria’s National renewable energy and Energy Efficiency Policy in 2015 resulted in a consortium signed between China and Nigeria, placing China at the helm of reviving Nigeria’s hydropower industry, yielding some positive outcomes so far. A partnership between technologically advanced and undeveloped countries, particularly Africa, is required to overcome significant avoidable hydropower constraints towards attaining their full hydropower output potential. In this way, the imperative to guaranteeing a globally cleaner and more sustainable energy future is more reassuring.

Generation expansion planning with revenue adequacy constraints

Generation capacity expansion models have traditionally taken the vantage point of a centralized planner seeking to find cost-optimal generation capacity to reliably meet load over decadal time scales. Often assuming perfectly competitive players, these models attempt to provide guidance for system planners without necessarily ensuring that individual generators recover all of their costs from market revenues during their lifetime. In this work, we incorporate revenue adequacy constraints in a two-stage generation expansion planning model. After making generation investment decisions in the first stage, day-ahead unit commitment (UC) and dispatch decisions are made in the second stage, along with market-clearing pricing decisions. To approximate a market equilibrium, the duality gap between the second-stage non-convex UC problem and its linearly-relaxed dual is used as a regularizer. Case studies are presented to contrast a traditional planning model with our revenue adequacy-constrained model, which find that our model leads to different planning decisions. More specifically, our model invests in more renewable generation capacity by incurring a small increase in the total costs.

Scope of Hydrogen-Based Vehicles in India: A Review

India is dealing with the problem of high automotive emissions as the number of vehicles on the road is rising. The primary cause of these emissions is the burning of crude oil. India imports crude oil from nations with abundant oil supplies because it lacks the resources to meet all of the country's energy needs for cars. There is a need to look for a carbon-free alternative fuel that is locally accessible in sufficient quantity to suit India's energy needs in order to address the problems related to oil imports and vehicle emissions. Hydrogen is a clean fuel choice among the potential energy sources because its combustion only yields water as a byproduct, and also due to its purity and high energy content, hydrogen energy offers a sustainable alternative to fossil fuels. India has the benefit of producing hydrogen from renewable sources like solar and wind during periods of lower demand because of its continuously expanding renewable energy generation capacity, and Asia is one of the continents with a wealth of these resources. Also, the exponential increase in food waste generation has prompted the scientific community to convert it into value-added resources. The main elements influencing the adoption of hydrogen as a cost-effective energy source in Asian nations are the availability of resources, safety requirements, public acceptance, and appropriate government incentives. The current analysis discusses the need to use hydrogen as an alternative fuel, its production processes, storage concerns, transportation, and the sources that are available. In various Asian nations like Japan, Korea, China, India, and Malaysia, particular focus has been placed on the notion of a renewable hydrogen economy. Perspectives on fuel supply, environmental effects, and social acceptance could help the biohydrogen energy sector evolve in a favorable way.

Long-Term Resource Adequacy in Wholesale Electricity Markets with Significant Intermittent Renewables

Growing amounts of intermittent renewable generation capacity substantially increases the complexity of determining whether sufficient energy will be available to meet hourly demands throughout the year. As the events of August 2020 in California and February 2021 in Texas demonstrate, supply shortfalls can have large economic and public health consequences. An empirical analysis of these two events demonstrates that similar supply shortfalls are likely to occur in the future without a paradigm shift in how long-term resource adequacy is determined for an electricity supply industry with significant intermittent renewables. An alternative approach to determining long-term resource adequacy that explicitly recognizes the characteristics of different generation technologies is outlined and its properties explored relative to current approaches.

Chance-constrained unit commitment with energy storage systems in electric power systems

The high penetration of renewables has amplified errors in forecasts of wind and solar power generation that are made to support the operation of power systems. To guarantee the security and reliability of the power system, sufficient dispatchable power generation capacity must be reserved. Various studies of the use of risk assessment to improve operational performance have been carried out. However, most methods of so doing are designed to cover a given risk level of uncertainty, which is determined from forecasts rather than actual results. As renewable generation and load capacity increase, defining the risk level without considering unit commitment (UC) may limit scheduling efficiency. In this study, chance-constrained programming is combined with goal programming to optimize risk-based UC. Solar power generation, wind power generation, and demand forecast errors are handled by the optimization of reserve schedules and adjustments of risk by imposing a penalty cost. The proposed risk-based UC model is transformed into a mixed-integer linear programming (MILP) problem using the equivalent deterministic form and piecewise linear functions to find an efficient solution. Case studies of a realistic Taiwan power system in 2025 are considered; these include peak (Summer 2025) and off-peak (Winter 2025) scenarios. Simulation results reveal that the flexible operation of a battery energy storage system (BESS) (upward/downward reserve) reduces risk costs by a significant amount (19.12%∼100%). Sensitivity analysis reveals how the risk preferences of the System Operator (SO) can be represented in terms of predefined risk levels and confidence intervals to capture the uncertainties in load, wind power generation, and solar power generation forecasts. The spinning reserve level is optimized to reduce the risk cost and the addition of BESS in flexible operations further reduces the risk cost. Lastly, pumped storage units as a downward reserve can reduce wind spillage and excess solar power generation costs.

Effects of cumulative energy aid projects on renewable energy generation capacity

Development cooperation plays an important role in helping aid recipient countries follow low carbon development pathways. Although the nature of cooperation varies across donors and recipients, intentions of renewable energy technology diffusion and structural changes are common for projects in the energy sector. Aid projects promoting renewable energy in developing countries are seldom assessed through econometric methods as the varieties and differences across projects and countries limit generalization. This paper attempts to explore how cumulative number of renewable energy aid projects enhances generation capacity in recipient countries. Using fixed-effect models on such type of projects from 2000 to 2013, we examine the effects of cumulative energy aid project numbers and other control variables on the yearly changes in generation capacity. A positive and statistically significant relationship was found suggesting cumulative learning effect from implemented projects. Presence of host country policies was also found to be important for growth in capacity. Findings of this study adds to the debate of whether density of energy aid projects leads to donor competition or greater fragmentation. Insights from this study can also improve aid providers’ strategy for interventions in the energy sector of recipient countries.

Effects of state and federal policy on renewable electricity generation capacity in the United States

Multiple studies have examined the impact of state-level renewable portfolio standards (RPS) on renewable electricity generating capacity. Two of the most widely cited of these papers (Yin and Powers, 2010; Shrimali et al., 2015) both conclude that as an RPS mandates higher shares of renewable generating capacity within a state, utilities respond by increasing the renewable electricity generating capacity. When we update the data for those models, we find that conclusion is not robust. We also modify those models and extend the datasets out to 2018, and in every model-permutation fail to corroborate the original conclusions. Finally, we examine the impact of the 2009 American Reinvestment and Recovery Act, and find it has had a significant, positive impact on renewable electricity generating capacity. We conclude that state-level RPS are not a sufficient substitute for federal action to reduce greenhouse gas emissions from the electricity sector. Federal leadership matters. This paper also demonstrates the importance of investigating the robustness of previous results to data refinements.

A hybrid fuzzy investment assessment framework for offshore wind-photovoltaic-hydrogen storage project

The offshore wind power-photovoltaic-hydrogen storage (OWPH) system has been considerably valued due to its advantages in improving power quality and increasing the absorption capacity of renewable energy power generation. To promote the rapid development and smooth implementation of the OWPH system, constructing a scientific investment decision-making framework is of utmost significance. Firstly, a criteria system that includes economy, resource, environment and support conditions, is established, where probabilistic hesitant fuzzy elements are introduced to depict the quantitative indicators and hesitant fuzzy linguistic term sets are employed by decision-makers to evaluate qualitative indicators. Then, a relative-entropy-based model is built to calculate the importance of decision-makers and a weighting model combining probabilistic linguistic-DEMATEL with the idea of maximizing deviation method is also built to compute the criteria weights. Moreover, an S-shaped utility-based PROMETHEE method is proposed to determine the optimal investment alternative(s). Finally, the proposed framework is applied in a case study to certificate the feasibility. The results illustrate that scheme A2 possesses the optimal comprehensive performance and the ranking order may vary with the change of decision-makers’ risk attitudes. This research provides investors with scientific decision reference and also extend the methods in the decision-making field.