The Belt and Road Initiative (BRI), initially proposed by China in Fall 2013, involves large-scale development of infrastructure, including energy infrastructure, in Asia, Europe, and Africa, and thus has the potential to affect global climate. In this work, we analyze publicly available information for 458 power plant development projects in 15 representative countries across the BRI regions from eight years prior to BRI (January 2005), to 6 years after BRI (June 2019) in which Chinese engineering contracting companies played a significant role. The data indicate that coal, gas, and solar photovoltaics (PV) activities increased to different degrees after BRI was introduced. We find that 75% of the new generation capacity after October 2013 has gone to fossil fuels, while the rest has gone to hydroelectricity (14%), solar PV (6%), wind (3%), and others (2%). Those numbers have important carbon emissions implications. Based on current trends, the total BRI-associated power development in the 15 countries could generate 37 (range 26–48) gigatonnes (Gt) of committed carbon dioxide (CO₂) emissions by the end of 2030, corresponding to 4–11% of the remaining carbon budget for the 1.5-degree climate goal. Extrapolation of these results to all BRI countries gives an estimate of 56 (range 40–72) Gt CO₂ for cumulative BRI-related committed emissions by 2030, corresponding to 7% to 17% of the remaining 1.5-degree carbon budget. If the projected growth of fossil fuel power generation in BRI slows down prior to 2030, there are commensurate reductions in emissions implications. To provide context for these numbers, we define a “greenness ratio,” which can be used to measure the level of environmental sustainability of BRI in the power sector.