The increasing prevalence of renewable energy resources introduces a high variability that complicates the task of energy management in modern power grids. Among other technologies, batteries have proven effective in managing power imbalances in such grids. However, the high cost of large-scale batteries, coupled with their enormous space requirements, could deter their adoption by large consumers such as shared facility controllers. The aggregation of residential energy storage units offers shared facility controllers (SFCs) an alternative way to leverage storage; however, a secure scheme that promotes fairness and transparency in the selection and compensation of shared storage unit owners is needed. To this end, an Ethereum smart contract that makes residential storage capacities available to SFCs via a double auction mechanism is proposed. The contract is written with solidity and deployed in the browser-based Remix-integrated development environment. Scenario tests prove the effectiveness of the smart contract in selecting and compensating the owners of shared storage capacities, according to predefined auction rules.