The MOST project aims to develop and demonstrate a zero-emission solar energy storage system based on benign, all-renewable materials. The MOST system is based on a molecular system that can capture solar energy at room temperature and store the energy for very long periods of time. This corresponds to a closed cycle of energy capture, storage and release. The MOST project will develop the molecular systems as well as associated catalysts and devices to beyond state-of-the-art performance and scale. Specifically, hybrid solar collectors utilizing up to 80% of incoming solar energy will be designed and tested together with heat release devices, that combine MOST with thermal energy storage (TES) enabling rapid temperature ramp-up cycles delivering large temperature gradients.