U.N. Secretary General Ban Ki-moon called for a revolutionary change in the world's energy mix. So why is the World Bank conducting business as usual? This new working paper by CGD senior fellow David Wheeler focuses on the bank's latest proposed venture, a huge coal-fired plant to be fueled by the Mmamabula coal field in Botswana. Using current cost estimates for coal-fired and low-carbon electricity, Wheeler calculates that a CO2 accounting charge of only about $35 per ton would be enough to make solar power competitive with coal. The difference, he argues, could easily be covered by the bank's Clean Technology Fund and other sources. He urges the bank to quickly adopt an explicit carbon accounting charge for all energy projects and says that given the current scientific consensus it would be very surprising if this is below $50/ton of CO2.