(355b) Comparison of Potential Alternative Process Options for Solar Energy Storage and Distribution

The TRANS-CSP study conducted by DLR in 2006 concluded that around 630.000 TWh(el) of renewable energy could be harvested economically in desert regions of Northern Africa [1]. However, the envisioned energy generation by Concentrating Solar Power (CSP) plants and its transport by high voltage lines face the drawbacks of low overall efficiency, leading to high system installation cost. Furthermore, for achieving an appropriate annual number of full-load plant operation hours, cost-intensive heat storage devices are necessary.

A new concept for storage and transport of solar energy from the earth´s desert belt is the use of Energy Carrying Compounds (ETS). This concept is based on material pairs showing an energy lean and an energy rich state. Said material pairs can be of inorganic nature, e.g. alkaline earth metal oxides/carbonates that have been presented elsewhere [2]. These ETS materials are converted into each other by uptake of solar energy in an endothermal reaction and release of the same amount of energy in an exothermal reaction. Using materials that are stable under storage and transport conditions, storage cost can be minimized when compared to CSP plants.  

Different organic and inorganic material pairs were recently investigated in our group with respect to reaction equilibrium and have been assessed with regard to overall solar-to-electricity efficiency by making use of the process modelling tool Aspen Plus.

In this contribution, material pairs and related process designs for ETS based solar energy storage recently assessed by our group are compared to each other and benchmarked to a reference process using the “classical” concept of solar power generation and distribution by power lines. The work was done within the research framework of Energy Campus Nuremberg (EnCN).

[1] German Aerospace Center (DLR) – Transmediterranean Interconnection for Concentrating Solar Power, 2006, Study commissioned by German government.

[2]    B. Müller, M. Helmle, M. Seitz, W. Arlt, Performance assessment of process chains for chemical solar energy storage, 9^th European Congress of Chemical Engineering, Den Haag, Netherlands, 2013