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A power system with 80% renewable energy sources (RES) requires significant provision of flexibility to balance the deviations of fluctuating solar and wind power. This paper focuses on how a smart mix of renewable generation technologies can reduce the demand for flexibility and therefore the overall system costs. To measure the demand for flexibility in systems with high RES generation, the term flexibility is defined and described using predictable indicators such as the difference between the highest and the lowest residual demand or the number of hours with negative residual load during a year. This definition is required to determine the optimal mix of RES installations. Optimization is performed for Germany based on the grid development plan of the transmission system operators. In contrast to most studies of the future energy system that foresee a further expansion of onshore wind, this paper shows that higher shares of offshore wind and, to some extent, photovoltaic are better suited to reducing the demand for flexibility and thus the cost of integrating fluctuating RES into the system. • Extended definition of flexibility demand for power systems based on renewables. • Offshore wind and photovoltaic requires less flexibility than onshore wind. • Uncertainty about the future renewable mix increases system integration costs. • Challenge: trade-off between levelized cost of generation and system integration. [ABSTRACT FROM AUTHOR]

The price effect of the rising share of renewable electricity, which is called ‘merit-order-effect’, leads to noticeable changes in the German power industry and debates about the electricity market design. This paper estimates the merit-order-effect induced by variable renewable energy in the German-Austrian electricity sector with a multivariate regression model. The research focus lies on the impact of the estimated effects on the marketability of variable renewable electricity generation. The results show a systematic decline of the average market revenues for wind and photovoltaic plants in the period from January 2011 to December 2013. Current market data shows a continuation of this trend into 2016. According to the German long term goals for the use of renewables, wind and solar power will play a crucial role in the future electricity generation mix. If investments in these technologies will be profitable without any regulatory remuneration mechanisms in addition to the market revenues, depends on the further cost degression and the development of the merit-order-effect. [ABSTRACT FROM AUTHOR]

Abstract: Wind energy development is booming worldwide with Germany and the United States being forerunners in installed capacity. Based on a review of relevant laws and regulations, policy, siting, and permitting documents, academic literature, and expert interviews, the paper compares the permit and environmental impact assessment (IA) policies and regulations pertaining to wind energy projects in both countries. The focus is on the potential of IAs in supporting an environmentally conscious development of wind power generation. This includes the analysis of IA regulations on the project level, strategic level impact assessment and planning processes, opportunities for public involvement and transparency of processes, and the clarity and predictability of the IA provisions. The findings suggest certain variations between both countries'' permit and IA processes for wind energy projects and further research needs, inter alia on the actual effects of strategic assessment of wind development on subsequent permitting. [Copyright &y& Elsevier]