**3. Conclusion**

To summarize, ANG holds strong promise in the area of fuel for transportation and other consumer sectors. The affordability depends on the availability of cost-effective adsorbents with high storage capacity with optimized deliverability. Though porous carbon, metal-organic framework, and covalent organic framework have shown promise, the target set by the DOE is yet to be complied with optimum deliverability. Selective compositions have been successful in achieving the storage capacity limits, the cost-effective and large scale production of such materials is under ways to materialize a commercializable product. These porous nanostructures are predicted to reach a high surface area up to 4000 m2 /g and beyond. A greater understanding of the pore structure, synthetic process, and mechanism of formation, pore controlling factors during synthesis and factors contributing towards the pore uniformity and stability would notably help towards the development of nonporous materials with high surface area and controlled pore structure. Therefore, the development of new cost-effective, thermally stable adsorbents with high uptake capacity and material strength is still desirable to further fulfill the commercial viability aspect of the technology.
