Sustainability is a topic of increasing interest. The United Nations has released a list of 17 goals for sustainable development for the global community. Blockchain is a recent technological innovation that shows great promise in changing industries. In this paper, we look specifically at smart grids and supply chain management systems as areas where sustainable technological innovation can happen. To identify software engineering aspects of blockchain in smart grids and supply chain management, we start upon online libraries focusing on engineering and information technology, and we opted for the methodology of systematic mapping studies in software engineering. The search strategy identified 535 papers, of which 60 were identified as main studies for our mapping. To the best of the authors' knowledge, no previous similar studies exist. Results of the study show that the research connecting blockchain technology to smart grids and supply chain management systems is still young. None of the techniques or systems have yet been implemented in a real life setting. As such, more work has to be done before we can look at the actual implications of putting such technologies into use. Software engineering practices could prove to be very useful in the process of development. We propose that future studies can focus on bringing the technologies closer to real life implementations, as well as how to involve the end users in the development of the blockchain-based systems.