Common auxiliary power (AP), which is also known as station AP, is the power used to drive the auxiliary equipment that is utilized by more than one unit in the entire power station. Generally, two types of cooling towers (CTs) are adopted in a closed cycle system, that is, an induced draft type or natural draft type depending on the technoeconomics involving capital cost, operating expenses, and consideration of site-specific issues. Induced draft cooling towers are preferred for power plants located near pithead power plants where operating expenses are lower (the overall power generation cost is less). On the other hand, natural draft cooling towers are preferred for power plants located at load centers (far off from the pithead where fuel transportation cost is high), as these do not involve any rotating equipment, thus saving AP for CT fans. The implementation of energy conservation measures for common AP reduces the average AP by 0.4%-0.7% of gross generation.