The cost of the reference BAC tower used in genGEO is given in Equation , where and are the specific costs of the reference BAC cooling and condensing towers, respectively. The specific cost is the ratio of tower cost to the heat rejected. Similarly, the cooling tower load fraction, , is the ratio of cooling tower heat load to total tower heat load, given in Equation S33. All tower costs are adjusted using process engineering cost index, , which our review discovered was not consistently applied to cooling tower cost in GETEM. The process engineering index represents cooling tower construction most appropriately, thus we adopt that index in genGEO.