Storing Hydrogen and Methane for Improved Clean EVs

Under the guidance of Northwestern University, a research group has developed and synthesized novel materials with ultra-high surface area and porosity for storing methane and hydrogen for fuel cell-powered vehicles.

Highly porous programmable sponge for clean energy storage. Image Credit: Northwestern University

Such gases are fascinating clean energy substitutes to fossil fuels that generate carbon dioxide. The designer materials, which are a kind of metal-organic framework (MOF), have the ability to store much more methane and hydrogen compared to traditional adsorbent materials at very low costs and safer pressures.

We’ve developed a better onboard storage method for hydrogen and methane gas for next-generation clean energy vehicles. To do this, we used chemical principles to design porous materials with precise atomic arrangement, thereby achieving ultrahigh porosity.

Omar K. Farha, Study Lead Researcher, Northwestern University

Adsorbents are porous solids that bind gaseous or liquid molecules to their surface. Due to its nanoscopic pores, the surface area of a 1-g sample of the Northwestern material (including a volume of six M&Ms) would cover 1.3 football fields.

Also, the novel materials could be a huge step forward for the gas storage industry as a whole. This is because several applications and industries necessitate the use of compressed gases like methane, hydrogen, oxygen, and others, stated Farha, who is an associate professor of chemistry in the Weinberg College of Arts and Sciences and a member of Northwestern’s International Institute for Nanotechnology.

The study combines both molecular simulation and experiment, and was recently published in the Science journal.

Farha is the lead and corresponding author of the study. Zhijie Chen, a postdoctoral fellow in Farha’s team, is the study co-first author. Penghao Li, a postdoctoral fellow in Sir Fraser Stoddart’s laboratory, Board of Trustees Professor of Chemistry at Northwestern, is the other co-first author. Stoddart is an author of the paper.

The ultra-porous MOFs, called NU-1501, are developed from organic molecules and metal ions or clusters that assemble themselves to develop highly crystalline, multidimensional, and porous frameworks.

According to Farha, to image the structure of a MOF, it is essential to imagine a group of Tinker toys in which the clusters or metal ions are the square or circular nodes and the organic molecules are the rods keeping the nodes together.

At present, methane- and hydrogen-powered vehicles need high-pressure compression to function. The hydrogen tank’s pressure is 300 times greater compared to the pressure in car tires. As a result of hydrogen’s low density, it is costly to achieve this pressure, and it could also be hazardous since the gas is extremely flammable.

By creating novel adsorbent materials that have the ability to store methane and hydrogen gas onboard vehicles at considerably low pressures, engineers and scientists can accomplish the goal of the U.S. Department of Energy for the advancement of the next-generation clean energy automobiles.

To achieve these targets, both the weight and size of the onboard fuel tank must be maximized. In this research, the highly porous materials balance both the gravimetric (mass) and volumetric (size) deliverable abilities of methane and hydrogen, thereby enabling the scientists to reach a step forward in achieving these goals.

We can store tremendous amounts of hydrogen and methane within the pores of the MOFs and deliver them to the engine of the vehicle at lower pressures than needed for current fuel cell vehicles.

Omar K. Farha, Study Lead Researcher, Northwestern University

The scientists at Northwestern University developed the concept of their MOFs and, in partnership with computational modelers at the Colorado School of Mines, verified that this class of materials is highly fascinating.

Furthermore, Farha and his group developed, synthesized, and characterized the materials. They also partnered with researchers at the National Institute for Standards and Technology (NIST) to perform high-pressure gas sorption experiments.

The study was financially supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy.


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