Energy consumption has emerged as one of the most contentious issues surrounding cryptocurrencies as a direct consequence of the widespread digital currency usage and popularity. Assuming that prices and user acceptance continue to grow at their current rates, cryptocurrency energy consumption will continue to rise in the future. There is no question that if greenhouse gas emissions continue at their current rate, there will be some adverse effects on global warming in the not too distant future. Environmentally Friendly and Unfriendly Cryptocurrencies Cryptocurrencies have an immediate negative impact on the environment. It is because of the energy-intensive processes involved with mining new coins and validating and recording crypto transactions on the blockchain. Each cryptocurrency’s amount of energy required to mine it is unique and determined by its consensus protocol. Some cryptocurrencies, such as Cardano (ADA) and Tron (TRX), use a proof-of-stake consensus protocol and therefore use relatively little energy. Hence, they are known to be environmentally friendly. Other cryptocurrencies like Bitcoin and Litecoin are renowned for being environmentally unfriendly because they are excessively energy-intensive. This exorbitant energy consumption is a result of their proof-of-work consensus protocol. Why is Bitcoin’s energy use in the headlines so frequently? Aside from discussions regarding its volatility, the media frequent...