In recent decades, renewable energy sources have attracted increasing interest around the world. According to a report on renewable energy [1], 19% of global final energy consumption comes from renewable energy and this figure continues to grow. In particular, new renewable energies (wind, solar, geothermal, biofuels) are experiencing extremely rapid growth. For example, wind energy is growing at 30% annually. These renewable sources are becoming so attractive because of their sustainability and low environmental impact. On the other hand, renewable energy sources, such as wind power and solar power, have a high degree of volatility and intermittency. This makes the penetration of renewable energy into the electricity system difficult and requires regulation to ensure that energy supply matches energy demand. Regulation is required by each Balancing Authority (BA) over multiple time scales, corresponding to the time-scales of electricity supply and demand volatility. The resources that provide these regulatory services are collectively called auxiliary services. Federal Energy Regulatory Commission (FERC) Orders 755 and 745 are intended to provide incentives for the provision of these services. The regulatory signal to balance electricity demand and supply is on average zero energy. This makes the use of deferrable charges particularly attractive as sources of ancillary services. The basic idea is to let the gap in overall electricity consumption of deferrable loads fill the gap between energy demand and supply. Many utilities already employ deferrable loads to reduce peak demand and manage emergency situations. Florida Power and Light (FPL), for example, has more than 780,000 customers enrolled in its OnCall savings program [2]. By registering among the paper sources ......rgy. Mean field sets have been used in the analysis of bulk charges [6,12], where optimality is achieved when the number of charges increases to infinity. More details on the general theory of mean field techniques can be found in [13–15]. The research described in this proposal concerns exploiting the flexibility of deferrable load aggregates to provide an ancillary service, without significant impact on consumer or industry needs. In the proposed work, a nonlinear model for charge aggregation is developed using the mean field limit, and this model is then approximated as an LTI system for controller design. A random control structure is proposed with the aim of realizing intelligent decentralized control and avoiding synchronization. Individual risk in the mean field model is examined and also eliminated with additional local control.