What is the fine-grained topic of the following text: The continuous stringent requirements of the environmental regulations along with the LNG fuel penetration and the development of port and bunkering facilities, render the use of the dual fuel engines an attractive alternative of the traditional ship propulsion plants based on Diesel engines running with HFO for reducing both the plant operating cost and environmental footprint. Only return the topic.
Dual fuel engines as an alternative for traditional ship propulsion plants for reducing operating cost and environmental impact