Integrated Energy Production and Storage Using Caes in Engineered Concrete Caverns Within Surface Lignite Quarries

Abstract

This work presents an integrated energy production and storage system based on Compressed Air Energy Storage (CAES), implemented within a surface lignite quarry. The proposed approach enables the reintegration of closed, degraded, or closed mining areas into the economic circuit while supporting environmental restoration, including the conservation of local flora and fauna. The concept capitalizes unused quarry surfaces and tailings dumps by installing photovoltaic panels on these deposits. In addition, artificial underground caverns are created at the quarry face using ecological concrete and segmented linings made of prefabricated reinforced concrete rings, designed for compressed air storage. In Romania, existing CAES initiatives are limited, mainly consisting of small-scale projects of up to 1 MWh, alongside a larger proposed project of approximately 300 MWh using external vessels, often associated with long investment payback periods. This study proposes a scalable alternative by integrating renewable energy generation with large-scale storage directly within lignite quarry perimeters. The system aims to achieve an estimated annual energy production of approximately 100 GWh per cavern, offering both economic and environmental benefits.