The viability of any project relies on the relationship between the capital costs and the benefits. The capital cost is most sensitive to the relationship of the distance between the cooling load and the source of cold water. Typical system studies have shown that for medium sized systems between the peak cooling load values of 5,000 and 20,000 tons, the maximum viable distance from the cooling load point to the cold water is 3 to 6 miles. Figure 4 was developed using data extracted from the referenced documents as well as actual project experience.
DWSC projects are sized based upon the existing and planned cooling loads. Depending upon the capital cost of the DWSC project relative to a conventional chilled based system, the installed DWSC capacity is designed to meet peak load or remain as a base loaded, bottoming type of facility. The value of a ton of installed DWSC capacity is considerable when evaluating the savings due to the reduction in operating costs. Much like in the power industry, high efficiency high capital cost systems are designed and operated as base loaded system. Less expensive, less efficient systems are utilized to meet peak loads.