  An increasing concern in power systems is how to elicit flexibilities in
demand, which leads to nontraditional electricity products for accommodating
loads of different flexibility levels. We have proposed Multiple-Arrival
Multiple-Deadline (MAMD) differentiated energy services for the flexible loads
which require constant power for specified durations. Such loads are
indifferent to the actual power delivery time as long as the duration
requirements are satisfied between the specified arrival times and deadlines.
The focus of this paper is the market implementation of such services. In a
forward market, we establish the existence of an efficient competitive
equilibrium to verify the economic feasibility, which implies that selfish
market participants can attain the maximum social welfare in a distributed
manner. We also show the strengths of the MAMD services by simulation.
