Blockchain has peculiar characteristics among various digital technologies due to its decentralised and cryptographic properties. The combination of intelligent energy systems and blockchain can innovate new forms of transactive energy and navigate the digital journey to transform the future of renewable energy systems. This review studies various blockchain implementations in the smart energy domain and presents the findings on operational and transactional challenges in a blockchain-based smart renewable energy system. We also identify the differences between operations and transactions in smart energy systems. Furthermore, we identify the most pronounced cryptocurrencies in different studies. The findings highlighted various challenges concerning the implementation of blockchain-based smart energy systems. We identified how these challenges spawn across operational and transactional deliverables. Building on these findings, we discuss various challenges impacting the operational and transactional domains, which we believe have significant value for researchers, practitioners, policy makers, entrepreneurs, and start-ups. It will provide long-term benefits to humankind in fulfilling energy requirements, promoting sustainable energy use by developing countermeasures to combat identified challenges and leveraging the optimal use of blockchain technology.