Optimal strategy of container vertical transportation energy structure conversion on port yard

Based on the dynamic programming theory, the minimum total cost during crane lifetime was taken as objective function, the carbon emission amount and investment cost were taken as constraint conditions, the dynamic changes of crane operation cost and carbon emission were considered, and the dynamic discrete programming model of container vertical transportation energy structure conversion on port yard was established. The athwart order method was carried out to solve the model, and the optimal strategy of crane energy structure conversion was determined. Calculation result shows that when rubber tire gantry (RTG) is 1 year old, the energy structure conversion should be completed at the start of the sixth year, and the total cost during the total lifetime of single crane under the optimal strategy is 9 376 600 yuan. When RTG is 2 years old, the energy structure conversion should be completed at the start of the fifth year, and the total cost during the total lifetime of single crane under the optimal strategy is 9 585 900 yuan. When RTG is equal to or older than 3 years, the energy structure conversion should be completed at the start of the second year, and the total cost during the total lifetime of single crane under the optimal strategy is 9 673 300 yuan. When the carbon limit value is less than or equal to 100 t, RTG energy structure should be converted immediately. When the carbon limit value is more than 400 t, the energy structure conversion should be completed at the start of the sixth year, and the constraint of carbon emission can be ignored. Because the carbon emission cost only accounts for 0.6-0.7 percent of operation cost and does not affect the decision greatly, it is advised to reduce carbon emission by increasing carbon tax or controlling carbon limit value.