Renewable energy is a global interest area in achieving sustainable development. Renewable energy sustainability has been assessed using the most commonly used dimensions of this concept: economic, environmental, social, and institutional dimensions. In this paper, we designed a composite index named the Renewable Energy Sustainability Index. The proposed index may represent a national monitoring mechanism that points out the strengths and weaknesses of a state in terms of renewable energy. The data were normalized by calculating the z-score. We tested the proposed index on a selection of 15 European countries ranked by final energy consumption and with different levels of development. The Kayser-Mayer-Olkin values were above the 0.700 limit, which indicates the robustness of each dimension. The proposed index reveals the development stages of renewable energy sustainability and can provide solutions to increase the sustainability of a country by improving positive impact indicators and mitigating negative impact indicators.

In 2015, Romania was the first country in Europe that achieved EU targets regarding the share of renewables in the generation mix, far ahead of the 2020 deadline. Starting with the energy structure in Romania, the paper: (1) analyses the evolution of the main indicators in the renewable energy sector, (2) discloses the perspectives of renewable energy in Romania synthesizing the main trends of development in the field, and (3) analyses the challenges facing with the development of renewable energy in Romania. Based on analyzing the exploratory data, the paper makes a preliminary prediction of the development of the sector for future decades and proposes targeted countermeasures and suggestions. Romania still has unexploited potential concerning renewable energy sources. Since Romania registered continuous economic growth, the demand for electricity is steadily growing, and this trend is expected to continue. Additionally, Romania could introduce a support mechanism for developing the potential of unexploited existing resources. The results of the present study may be useful for further research regarding public policies for the development of renewable energy. Furthermore, it can represent a useful analysis in order to identify future trends of renewable energy in Romania.