ABSTRACT
An estimate of the costs of converting a diesel engine to dual-fuel operation can only be made on a somewhat tentative basis. There are a wide variety of diesel engines of different makes, sizes, and ages on the market and in operation. These have numerous design and operational features that make universal generic retrofit equipment hard to devise when premium performance with cost savings is targeted. The costs are also a function of the number of engines to be converted and the type, availability, and cost of the fuels that are to be used with them. The potential benefits that arise from the employment of gaseous fuels that can permit, in principle, some design change reductions in the specific energy consumption can help to contribute toward a reduction in overall costs. For example, the liquid fuel tank and other support equipment and facilities may be reduced significantly from those of regular engines, which operate exclusively on liquid fuels. However, for example, the variable cost differential between the two types of engines in transport applications would have to include the costs of additional items, such as those of the fuel containers, maintenance, and insurance, and the associated cost of fuel gas compression. Against these costs is the value of the benefits of having positive features that are associated with the operation of properly converted engines, such as those of the invariably cheaper gaseous fuel and the improved environmental features. The economy of operating engines, whether on natural gas or other gaseous fuels, is greatly influenced by other factors that may include unit load and plant load, hours operated per year, fuel cost and its variations, capital and operational costs, and the prevailing and future prices of liquid fuels and electric power.
