A consortium consisting of Boeing, NASA's Glenn Research Center, MTU Aero Engines (Germany), and the U.S. Air Force Research Laboratory is working on development of jet fuel blends containing a substantial percentage of biofuel. British Airways and Velocys have entered into a partnership in the UK to design a series of plants that convert household waste into jet fuel. 24 commercial and military biofuel flights have taken place using Honeywell “Green Jet Fuel,” including a Navy F/A-18 Hornet. In 2011, United Continental Holdings was the first United States airline to fly passengers on a commercial flight using a blend of sustainable, advanced biofuels and traditional petroleum-derived jet fuel. Solazyme developed the algae oil, which was refined utilizing Honeywell's UOP process technology, into jet fuel to power the commercial flight. Solazyme produced the world's first 100 percent algae-derived jet fuel, Solajet, for both commercial and military applications. Oil prices increased about fivefold from 2003 to 2008, raising fears that world petroleum production is becoming unable to keep up with demand. The fact that there are few alternatives to petroleum for aviation fuel adds urgency to the search for alternatives. Twenty-five airlines were bankrupted or stopped operations in the first six months of 2008, largely due to fuel costs. In 2015 ASTM approved a modification to Specification D1655 Standard Specification for Aviation Turbine Fuels to permit up to 50 ppm (50 mg/kg) of FAME (fatty acid methyl ester) in jet fuel to allow higher cross-contamination from biofuel production. Worldwide consumption of jet fuel Worldwide demand of jet fuel has been steadily increasing since 1980. Consumption more than tripled in 30 years from 1,837,000 barrels/day in 1980, to 5,220,000 in 2010. Around 30% of the worldwide consumption of jet fuel is in the US (1,398,130 barrels/day in 2012). Taxation Article 24 of the Chicago Convention on International Civil Aviation of 7 December 1944 stipulates that when flying from one contracting state to another, the kerosene that is already on board aircraft may not be taxed by the state where the aircraft lands, nor by a state through whose airspace the aircraft has flown. However, there is no tax regulation in the Chicago Convention to refuel the aircraft before departure. The Chicago Convention does not preclude a kerosene tax on domestic flights and on refueling before international flights. Kerosene tax can be levied throughout the European Union on domestic flights and between Member States