In the last few years, the adoption of renewable technologies and energy-efficiency strategies has become increasingly important for reaching the ambitious target of an 80-95% reduction in greenhouse gas emissions by 2050. In order to limit the increase in the Earth's average temperature, fully renewable energy systems have to be adopted in all energy sectors.

As such, several countries have agreed on the necessity of developing and implementing a novel sustainable energy paradigm in the building, transport, and industrial sectors. To support this new approach to energy use and production, scientists and companies have focused their attention on the use of renewable energy technologies, improvements in functional energy use, energy efficiency, novel efficient energy conversion systems, etc.

In this context, this Special Issue, "Renewable Energy Systems 2023", aims to summarize the most recent and important advancements and studies dealing with the integration of renewable technologies into new or existing systems for the production of energy and non-energy outputs. The papers presented within this Special Issue reprint cover the potential use of renewable energy for power production, heating, cooling, water management, and transport.

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