The costs of a process that include the cost of raw materials and all other chemicals that are consumed in the process such as catalysts, the cost of the utilities such as steam, electricity, fuel, cooling water, process water, compressed gases, etc. The variable costs also include unscheduled maintenance costs, royalties, licence costs, transportation costs, and costs associated with quality control and other forms of monitoring. The variable costs of a process are dependent on the rate of production. The sum of the fixed costs and variable costs is the total cost of the process. See process economics.