Bitcoin is a digital currency based on a peer-to-peer payment system managed by an open source software and characterized by lower transaction costs, greater security and scalability than fiat money and no need of a central bank. Despite criticisms about illegal uses and social consequences, it is attracting the interest of the scientific community. The purpose of this work is to define and evaluate the current trends of the literature concerned with the sustainability of bitcoin, considering the environmental impacts, social issues and economic aspects. From the analysis it emerges that the transition of the whole monetary system in the new cryptocurrency will result in an unacceptable amount of energy consumed to mine new bitcoins and to maintain the entire virtual monetary system, and probably bitcoin will remain a niche currency. Blockchain, which is the base for a distributed and democratically-sustained public ledger of the transactions, could foster new and challenging opportunities. Sharing the framework of medical data, energy generation and distribution in micro-grids at the citizen level, block-stack and new state-driven cryptocurrencies, may benefit from the wide spread of blockchain-based transactions. Under the perspective of its being a driver of social change, bitcoins and related blockchain technologies may overcome the issues highlighted by numerous detractors.

Blockchain, a distributed and democratically-sustained public register of the transactions of the digital currency "Bitcoin", proposed by Satoshi Nakamoto a pseudonym of a hided developer in 2009, has been the driver of a huge number of initiatives devoted to develop and implement a peer-to-peer distributed database, and with no central authority created as an open source software. Expansion of Bitcoin, as well as other digital currencies, has been due to lower transaction costs, high security protocols and lack of inflation with respect to fiat money and no need of a clearing entity or a central bank. Although, environmental issues related to the use of this currency and, in particular, in the energy consumes, have been raised by the scientific community, but no signals of limiting factors have been detected until now. The hidden in the wings blockchain technology has been recognized the driver of innovation in various fields, contributing to create a more sustainable world. The purpose of this paper is to describe both the recent trends in the applications of the blockchain technology in the cryptocurrencies market and the new projects considering the environmental sustainability (energy consumption, materials depletion) and social impacts. The contribute of blockchain in reducing and accelerating bureaucracy and incentivizing environmentally friendly behaviour, has been discussed. Although the environmental issues related to the energy consumed in Bitcoin mining may scare companies in adopting the new technology, there is no evidence of limiting factors or carrying capacity of the entire system. In future the development of a less energy intensive alternative for validating the blocks to stack in the distributed database, would render the blockchain the ideal candidate for the applicability of sustainability paradigms in the economic, environmental and social sectors.