A review on the utilization of hybrid renewable energy

The utilization of renewable energy is significantly important for the world because global energy consumption is increasing, while conventional energy sources are no longer sufficient to meet the energy demand, triggering energy crises. However, variation in solar radiation and wind speed caused by climate and weather conditions restricts the stable operation of renewable energy systems, therefore, causing the output to fluctuate. A hybrid renewable energy (HRE) system can be highly efficient by combining multiple renewable energy sources and is regarded as a promising solution to the above issue. In this review, a comprehensive summary and discussion of the uses of HRE in terms of space heating, cooling, hot water usage, power generation, hydrogen production, drying and multi-generation are conducted. Hybrid system configurations, specific devices, application procedures, and performance are reviewed. Moreover, the challenges and outlook for HRE utilization are discussed, including the following points: proper use of the local sources in view of disperse and regional distribution of renewable energy; development of hybrid storage subsystems for HRE to improve the stability of the energy supply; further optimization of the operation strategy and system size to minimize the cost in order to promote the application; and, clear identification of the supporting local policies of renewable energy, especially considering HRE. Furthermore, the research potential is described for HRE utilization integrating direct CO2 reduction.