The objective of this study is to contribute to energy efficiency in the manufacturing industry, more particularly in high energy-consuming integrated production plants. This study considers particularly job-shops where the energy necessary to realize production plans must be minimized while satisfying make-span constraints. When machines are operated in a standard way, for a given production plan, the component of energy consumption which is a variable corresponds to the unproductive periods of the machines between two operations. In this study, the cases of mechanical and thermal machines are examined to identify the energy optimal policies which allow coping efficiently with their unproductive periods. The question was at first to identify the conditions in which a shut down or an idle regime was a better solution for a machine during an unproductive period, however, the performed analysis has led to considering hybrid solutions where the machine is in a first stage shut down and then put into an idle mode until its startup to perform the next operation.

This paper considers the problem of structuring the urban airspace so that UAVs-based-urban-logistics can be performed efficiently. A two-level structure is proposed to ease accessibility of the logistics service and the safety of traffic in the urban airspace. This gives way to cope with two problems: one related with the design of local networks and another one related with the design of corridors between different urban subareas. In both cases, heuristic solution processes are proposed, discussed and illustrated.

This study considers a flexible job-shop scheduling problem where energy cost savings are the primary objective and where the classical objective of the minimization of the make-span is left in the background. An original mixed-integer formulation of this optimization problem is proposed where the processed flows of material and their timing are explicitly considered. Considering the computational complexity of this problem, it is shown how this modelling approach eases the design of a comprehensive heuristic based on energy considerations. The proposed approach is illustrated through a small scale problem.

Diesel power plants use diesel engine prime movers powered mainly by heavy fuel oil or diesel fuel and with potential for conversion to gas engines or dual fuel engines. The aim of this study was to investigate the feasibility of converting diesel engines to dual fuel engine. Natural gas is an attractive substitute to diesel and heavy fuel oil since it is cleaner, more efficient and cheaper. The conversion of a conventional diesel engine to dual fuel engine requires of the fuel injection system, reduction in air to fuel ratio, and reduction of compression ratio. The main challenges of the conversion to dual fuel diesel power plants are the cost of downtime to carry out the conversion hence lost generation, delayed transition to zero carbon emissions by advancing the use of natural gas, safety risks from use of natural gas and negative impact of methane emissions and other greenhouse gases associated with natural gas combustion. Co-combustion with biofuels and use of bio methane can assist in mitigating emissions from dual fuel diesel power plants.