Used Automobile Oil May Be a Source of Hydrogen

While the phrase “Hydrogen Economy” is heard often these days and is widely anticipated by people who hope to see our world function using renewable energy carriers, all agree that a lot of complex preparatory work still needs to be done.

One of the more interesting hydrogen projects going on now at the Florida Solar Energy Center (FSEC) deals with a unique way to produce hydrogen. Dr. Ali Raissi and Karthikayan Ramasamy are developing a process to produce hydrogen based on reformation of used automotive lubricating oils.

Used lube oil — often considered just another substance to be disposed of — can be valuable when recycled as a re-refined lubricant or as an energy source. Each year, Floridians generate more than 45 million gallons of used lubricating oils. Typically, used lubricating oil is delivered at a cost of about 10 cents per gallon, making it a potentially inexpensive source for local production of hydrogen. Another interesting attribute of used oil is that it is collected in central facilities near high population areas – exactly where hydrogen is needed to fuel automobiles and transportation systems.

Most lube oils contain a complex mixture of higher hydrocarbons very difficult to break down using thermal energy alone. After all, lube oils are especially formulated to withstand very high temperatures encountered within the internal combustion engines of automobiles. At FSEC, Raissi and Ramasamy have built a thermocatalytic reactor and process that uses supercritical water to reform lube oils into a high pressure, hydrogen-rich synthetic gas. This process is especially useful for coupling to conventional refrigeration plants for hydrogen liquefaction. The energy required for compressing hydrogen prior to liquefaction is provided upstream of the process using thermal energy instead of mechanical energy downstream after hydrogen gas evolves.

Water becomes a supercritical fluid at temperature above 374.2°C and pressure over 22.1 MPa. In the Supercritical region, densities are a fraction of that of normal liquid water, while solubility behavior is closer to that of high-pressure steam.

To date, FSEC researchers have operated this system successfully using both virgin and used/discarded oils and have demonstrated the viability of the process.

To view a video showing the laboratory apparatus and an animation of the FSEC process for producing hydrogen from used lube oil, click on http://media.fsec.ucf.edu

The Florida Solar Energy Center, a research institute of the University of Central Florida, is the largest and most active state-supported energy research center in the country. Current research activities include solar water and pool heating, solar electric and distributed generation systems, energy-efficient buildings, alternative transportation systems, hydrogen fuel, fuel cells and other energy areas. For more information about the center, visit www.fsec.ucf.edu or call the FSEC Public Information Office at (321) 638-1015.

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