Natural gas is much cheaper, cleaner and more abundant compared to oil. That's according to engineer Christopher Wilmer, who says Natural gas is an attractive alternative to power the world’s vehicles. However, it does have its own set of challenges. For starters, the gas needs to be highly compressed for effective use. In his SolveForX talk, titled Efficient Gas Storage and Separation, Wilmer discusses his ideas for improved collection and usage methods.
Storing natural gas more effectively would eliminate heavy tanks and expensive fueling stations. Around 65 million homes in the United States currently have natural gas and could fuel vehicles in their own garage. Natural gas is collected when oil fields are collecting the oil, but the gas is burned away instead of being stored, contributing to greenhouse gas emissions.
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Every year, 100 billion cubic meters of natural gas is being burned away. This represents approximately one percent of the world's energy demand. At the nanoscale, activated carbon has space for natural gas to be stored, but no one has found an efficient way to store and use the gas. Wilmer proposes using Metal Organic Frameworks as the porous material that can store and discharge the gas.
MOFs have trillions of perfectly formed and uniform spaces to store the natural gas. The pockets inside the framework can be programmed to stick to certain gas molecules and repel others, allowing for easy gas separation.
Wilmer uses plastics as an example of the usefulness of MOFs. Prior to the 1950s, plastics were not widely used. Fast forward to to 2015 and they're everywhere. Polymers grow as chains of monomers in one dimension while MOFs grow in all three dimensions. Instead of floppy chains of polymers, rigid three-dimensional structures are created when building the framework at the nano level.
Using customized, fully designed structures for gas storage is far superior to the random porosity size and shapes of activated carbon. The atomic precision of pores allow natural gas to be stored at around one quarter the pressure of current tanks. Refueling stations can be made cheaper and without high pressure. Meanwhile, the tanks can be lighter, cheaper and molded into different shapes.
Shape flexibility will allow vehicle manufacturers to design their tanks around the car requirements (instead of designing pockets for the large bulky tanks in their vehicles). Wilmer hopes this technology can also allow lawnmowers, golf carts or drones to successfully use natural gas.
Wilmer is full of ideas for the usage of Metal Organic Frameworks, well beyond natural gas storage. Medical oxygen, semiconductor manufacturing, and carbon capturing will all benefit from gas storage improvements.