Natural gas, mostly methane, is an attractive alternative transportation fuel to gasoline, but it suffers from a low volumetric energy density at ambient conditions. The two densification strategies in the market today, liquified and compressed natural gas, require costly infrastructure and bulky, expensive onboard fuel tanks. An alternative strategy is to pack the vehicular fuel tank with a nanoporous material adsorbent, allowing storage at room temperature and a moderate pressure. The Advanced Research Projects Agency - Energy (ARPA-E) subsidiary of the US Department of Energy set a target that an adsorbent should deliver 315 volumes STP of methane per volume of adsorbent to achieve a volumetric energy density competitive with compressed natural gas by using a 65 to 5.8 bar pressure swing.<br/><br/>Due to the high tunability of advanced nanoporous materials, one can combine different molecular building blocks to arrive at an unprecedented number of possible materials. In the attempt to explore this chemical space, researchers have designed materials in silico to construct databases of zeolites, metal-organic frameworks, zeolitic imidazolate frameworks, porous polymer networks, and covalent organic frameworks. Here, we screen these databases, consisting of over 650,000 materials, for the most promising candidates for methane storage using molecular simulations. In the process, we unearth relationships between geometric structural characteristics and performance to elucidate guidelines for design. Our screening suggests that the ARPA-E storage target cannot be reached. By considering other operating conditions, we assess what performance we can reasonably expect from nanoporous materials in vehicular methane storage.

Materials genome in action: Finding a nanoporous material for methane storage

249th National Meeting (2015)

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