Cambridge University has introduced a significant update to its Bitcoin Electricity Consumption Index (CBECI) after a three-year hiatus, leading to a substantial revision in its estimates of Bitcoin's global energy consumption attributable to miners. The revised data challenges earlier assessments that portrayed Bitcoin as a massive energy consumer. Specifically, the CBECI model, for the year 2021, initially estimated Bitcoin's electricity consumption at a staggering 104 terawatt-hours (TWh). However, the revised estimate now stands at a significantly lower 89.0 TWh, marking a notable reduction. To put this in perspective, one terawatt-hour (TWh) equates to one trillion watts of energy output for a duration of one hour. Similarly, the estimate for 2022 underwent a downward adjustment of 9.8 TWh, dropping from 105.3 TWh to 95.5 TWh. This places Bitcoin's electricity consumption for that year in line with the energy used by U.S. tumble dryers, which stands at 108 TWh. The previous methodology employed by the university assumed that any "profitable" hardware introduced in the previous five years contributed equally to the network's hashrate.

However, this approach began to reveal its limitations following China's mining restrictions in 2021. Alexander Neumueller, the author of the report, explained that the overestimation stemmed from not accounting for the increasing efficiency and power of Application Specific Integrated Circuits (ASIC) hardware devices used in mining. These improvements led to a more energy-efficient mining process, ultimately reducing the overall energy consumption. Despite the update, Cambridge's revised methodology still relies on certain assumptions and simplifications. Nevertheless, the updated CBECI provides a more accurate understanding of Bitcoin's energy consumption. The current estimate for 2023, according to the university, stands at 70.4 TWh, reflecting the ongoing trend of improved energy efficiency in the Bitcoin mining industry.

In summary, Cambridge University's updated Bitcoin Electricity Consumption Index challenges earlier perceptions of Bitcoin's energy consumption, highlighting a significant reduction in energy usage. This revision underscores the evolving landscape of Bitcoin mining, characterized by increasing efficiency and the adoption of more energy-efficient hardware. While questions about the environmental impact of cryptocurrency persist, the updated index provides a more nuanced perspective on the energy dynamics of the Bitcoin network.