Larger share of total energy consumed by mobile network operators (MNOs) is wasted to ensure seamless coverage. Three to six MNOs covering the same geographical area results in even more energy waste. Division of scarce resource, i.e., spectrum into small chunks also deteriorates the overall performance. With exponential growth of the traffic and insignificant marginal revenue, it is time for the regulators and MNOs to resort to new ideas in order to reduce operational cost and devise appropriate mechanisms to ensure business as well as environmental sustainability. In this paper, we propose a double auction based energy saving market where MNOs share coverage and spectrum to save energy. In this market each MNO submits bid and asks to an independent auctioneer simultaneously. The bid is the offer to offload its total traffic to some other MNO along with releasing its own spectrum to be used by the latter. Similarly, the ask is the offer by a MNO to accept excess load along with the spectrum. The auctioneer matches the bids and asks, determines the trading price and makes the offloading decisions to minimize the total energy consumption. We show that even though the information is hidden among the MNOs, this mechanism allows the MNOs to save significant percentage of energy.