Exelon agreed to buy fuel-cell power plants with 21 MW of capacity that Bloom Energy plans to install at 75 corporate sites in four states. Commercial customers including AT&T will purchase the electricity for each plant’s ability to provide power locally with less pollution and more reliability than the grid. Fuel cell generators produce electricity where it’s consumed from natural gas through a chemical reaction that produces fewer carbon emissions than plants that burn fuel. This is Exelon’s first investment in systems from Bloom, which will operate and maintain them. Terms were not disclosed.