The Carbon Sponge: The Use of Adsorbed Natural Gas in Vehicles Authors: Carol Faulhaber, Sarah Barker, Jacob Burress,

1. Motivations • Big Picture • ALL-CRAFT is investigating methods for storing large capacities of natural gas at low pressures using Adsorbed Natural Gas. Compressed Natural Gas tanks in current natural gas vehicles are large cylindrical shaped tanks that take up passenger and trunk space. The purpose of ALL-CRAFT is to design ANG natural gas tanks that conform to the available space in any vehicle. The use of natural gas in vehicles is more environmentally friendly, costs less, and would allow the United States to utilize national resources. ALL-CRAFT is currently investigating the storage capacity of carbon made from waste corn cob to use in ANG natural gas tanks. • Our part • We are analyzing the lab’s current method of testing the storage capacity of carbon. We conducted two experiments to find the appropriate time to outgas carbon samples and expose them to methane. We also tested several samples of carbon, comparing the storage capacities for each sample, and conducted and complete isotherm of one sample to find the deliverable amount of methane, or the amount of methane actually used by the engine, and the pore size distribution. • 2) Experimental Setup • Outgassing Time Experiment: • Step 1: Outgas sample cell without carbon for 30 minutes at 400°Celsius and then measure mass. Then attach sample cell to methane setup and expose to methane for 20 minutes and weigh. • Step 2: Insert carbon sample into the sample cell, outgas sample for 4 hours at 400°Celsius, and measure mass. • Step 3: Attach sample cell to methane setup, expose to methane for 4 hours at 500 psig, and measure mass. • Step 4: Outgas sample for 3 hours, measure mass, attach to methane setup, expose to methane for 4 hours at 500 psig, and measure mass. Repeat this process, but substitute 2, 1, and .5 hours for the outgassing time. • Equilibration Time Experiment: • Step 1: Outgas sample cell without carbon for 30 minutes at 400°Celsius and then measure mass. Then attach sample cell to methane setup and expose to methane for 20 minutes and measure mass. • Step 2: Insert carbon sample into the sample cell, outgas sample for 4 hours at 400°Celsius, and measure mass. • Step 3: Attach sample cell to methane set up, expose to methane for 8 hours at 500 psig, and measure mass. • Step 4: Outgas for 4 hours at 400°Celsius, measure mass, attach to methane setup, expose to methane for 4 hours at 500 psig, and measure mass. Repeat this process, but substitute 3, 2, 1, .5, .25. and .166 hours for the exposure time. Carbon Sample Testing: Step 1: Outgas sample cell without carbon for 30 minutes at 400°Celsius and then measure mass. Then attach sample cell to methane setup and expose to methane for 20 minutes and measure mass. Step 2: Insert carbon sample into the sample cell, outgas sample for 2 hours at 400°Celsius, and measure mass. Step 3: Attach sample cell to methane setup, expose to methane for 1 hour, and measure mass. Step 4: Outgas for 2 hours at 400°Celsius and measure mass. Attach to methane setup, expose to methane for 1 hour at 500 psig, and measure mass. Full Isotherm for Carbon Sample S-33/K Step 1: Outgas sample cell without carbon for 30 minutes at 400°Celsius and then measure mass. Then attach sample cell to methane setup and expose to methane at 500, 450, 400, 350, 300, 250, 150, 100, 75, 50, and 25 psig for 30 minutes each, measuring the mass in between each exposure. Step 2: Insert carbon sample into the sample cell, outgas sample for 2 hours at 400°Celsuis, and measure mass. Step 3: Attach sample cell to methane setup, expose to methane for 1 hour at 500 psig and then at 450, 400, 350, 300, 250, 200, 150, 100, 75, 50, and 25 psig for 1 hour each. Between each exposure measure the mass of the sample cell. Figure 2: Outgassing pump and oven Figure 3: Methane Setup • 3) Results and Discussion • record for adsorption held by AGLARG. Using this data the deliverable amount of methane calculated is 172.2 g/kg for a pressure range of 500-25 psig. • 4) Conclusions • The results of the equilibration and outgassing experiments have enabled the lab to test a sample of carbon in about one-fourth of the original time. We tested several samples of carbon and performed a complete isotherm on one sample using the results of the equilibration and outgassing experiments. Using the data collected from the isotherm, the pore size distribution and deliverable amount of methane are found. The amount of methane adsorbed by the sample is also higher than any other sample recorded, giving hope to the future of ALL-CRAFT, and helping us reach our goals. • 5) Acknowledgements • - Funding provided by the National Science Foundation. The Carbon Sponge:The Use of Adsorbed Natural Gas in Vehicles Authors: Carol Faulhaber, Sarah Barker, Jacob Burress, Dr. Peter Pfeifer From fig. 4 one can determine that the results for the 30 minute and one hour outgassing times are significantly less, and therefore not as good as the 2 hour outgassing time. From fig. 5 one can see that the 30 minute equilibration time is the minimum time needed to achieve a result within the error bars. To be on the conservative side we have chosen to use 1 hour. Fig. 6 represents the methane uptake of several samples of carbon at 500 psig. The purpose of testing several samples of carbon is to optimize the activation process. Fig. 7 represents the amount of methane stored in a sample of carbon per mass of carbon. This sample of carbon has an uptake that is about 20% better than the current