Arabian American Development Company (ARSD) has signed a contract with Gevo to extend toll processing services of the hydrocarbon processing demonstration plant at its South Hampton Resources (SHR) facility in Silsbee, Texas and construct a second demonstration unit to provide Gevo with toll-processing services necessary to process up to 16,000 pounds (7 tonnes) per month of mixed octane materials produced on the existing isobutanol to jet demonstration unit.