Professor Andrew Urquhart from Birmingham Business School has highlighted concerns over Bitcoin's energy consumption, emphasizing the environmental impact of its proof-of-work (PoW) system. According to the 2025 Cambridge Digital Mining Report, Bitcoin's annual electricity usage is estimated at 138 TWh, with 52.4% sourced from sustainable energy. The report also indicates a total emission of 39.8 million metric tons of CO2 equivalent. The discussion gains further relevance as Ethereum's transition to proof-of-stake (PoS) in 2022 slashed its energy consumption by nearly 99.9%, prompting questions about Bitcoin's potential shift to more sustainable methods. The article also considers the role of Bitcoin mining in supporting green energy by using excess renewable power, though its overall environmental impact remains a topic of debate.