(409e) Dimethyl Ether Chemical Storage Cycle for Uninterrupted Renewable Power

With increasing global demand for limited fossil fuel resources and escalating atmospheric greenhouse gas (GHG) emissions, there is growing interest to develop technologies for harnessing intermittently available renewable energy sources such as solar energy. In terms of end use of primary energy, electrical power generation is among the fastest growing sectors and also represents a major stationary source (~40%) of global CO₂emissions.

To date, the use of non-hydro renewable energy for electrical power generation has thus far been limited to peak shaving rather than base-load applications. In the absence of efficient large-scale energy storage options, the intermittent nature of renewable energy sources remains the grand challenge for baseload power generation. For example, to provide uninterrupted power supply of 100 MW from solar energy in the US (with solar energy being available for 4.8 h of a 24 hour-day), approximately 2 GWh of electrical energy storage is needed.

Carbon storage cycles (CSC) involving cyclic transformation of carbon atoms between carbon dioxide and carbon fuel have the potential to achieve high storage efficiency (~54–59%) for GWh-level energy storage with much reduced storage volumes compared to other options. During the period of renewable energy availability, the cycle utilizes stored liquid carbon dioxide to synthesize a carbon fuel and then store it in liquid state. When renewable energy is not available, the carbon fuel is oxidized to deliver electricity. The produced carbon dioxide is captured, liquefied and stored for reuse during energy availability [1].

Here, we review the novel features of the CSC, and three exergy based metrics that allow systematic screening of carbon fuel to be utilized in the cycle and present the process simulation details and results of dimethyl ether chemical storage cycle [2]. Dimethyl ether is identified as one of the attractive carbon fuel candidates by the exergy based metrics and the resulting ~57% storage efficiency is in accordance with the prediction of the metrics.

[1]       Al-musleh EI, Mallapragada DS, Agrawal R. Continuous power supply from a baseload renewable power plant. Applied Energy 2014;122:83.

[2]       Gençer E, Al-musleh E, Mallapragada D, Agrawal R. Uninterrupted Renewable Power through Chemical Storage Cycles. Current Opinion in Chemical Engineering 2014.