An estimated 20,000 aircraft currently ferry some 3 billion passengers around the world annually, and contribute about 2% of the world’s annual greenhouse gas emissions. In 20 years, more than 50,000 planes and many more passengers could be flying. The difficulty in apportioning responsibility for jet emissions among countries makes it among the more complex problems of the global climate change fight. Also, as jet fuel prices rise alongside those of crude oil, it makes sense for governments and airline companies to move towards alternative sources of fuel.
Budget carrier SpiceJet Monday operated India’s first “technology demonstrator” flight on biojet fuel, which Ajay Singh, the airline chief, said could “reduce dependence on traditional aviation fuel by up to 50% on every flight and bring down fares”.
Dehradun-based CSIR-Indian Institute of Petroleum (IIP) manufactured 330 kg of biofuel especially for Monday’s 40-odd-minute Dehradun-Delhi flight. The Bombardier Q400 turboprop aircraft with 28 people on board burnt a mix of 75% traditional aviation turbine fuel (ATF) and 25% oil extracted from the Jatropha plant, sourced from nearly 500 farmer families in Chhattisgarh. Biofuel blends for jet engines can also be prepared using biomass, animal fat, vegetable oil, agricultural waste, and natural gas. The bio-oil concentration can rise to 50%, beyond which, however, the combustibility of the fuel can be impacted.
Science and Technology Minister Harsh Vardhan said only “three to four nations are using biojet fuel”. In 2008, Virgin Atlantic flew a Boeing 747 between London and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts. In January this year, Australian flag carrier Qantas operated a 15-hour flight from Los Angeles to Melbourne using a blended fuel that was 10% derived from Brassica carinata, an industrial variety of mustard.
The International Air Transport Association (IATA) is committed to an average annual improvement of 1.5% in fuel efficiency from 2009 to 2020, a cap on net aviation carbon emissions from 2020 (carbon-neutral growth), and a reduction in net aviation carbon emissions of 50% by 2050, relative to 2005 levels. IATA has also set a target of 1 billion passengers flying on aircraft using a mix of clean energy and fossil fuels by 2025. It has noted that given the current immaturity of the supply chain of the aviation biofuel industry, these fuels have lower economies of scale and can cost almost two to three times higher than conventional ATF. So far, more than 5,000 commercial flights have been operated across the world using biofuels.
An international research programme led by NASA reported last year that the use of biofuels can reduce particle emissions in jet exhaust by as much as 50%-70%. But the equation is sometimes not simple: In a 2014 analysis of biofuels for the aviation industry, IATA had noted: “According to a lifecycle assessment by the Yale School of Forestry on the plant jatropha (a tropical drought-resistant, oil-rich flowering plant), just one source of potential biofuels, its use could either reduce greenhouse gas emission by up to 85%, or increase them by 60%, depending on the circumstances in which it is produced.”
Commercial use of aviation biofuel is still some way away. The infrastructure to mass-produce biojet fuel, and to deliver it at airports, is awaited. The airport at Los Angeles is one of the few that have the relevant infrastructure to support biofuels. Fuel companies are still working out sustainable ways to manufacture biofuel for aircraft. The 2014 IATA analysis said that the production of the first generation of biofuels had shown that the displacement of other agricultural activity, if not monitored carefully, could become a significant long-term concern. Second generation fuels, it said, posed greater extraction challenges. The Indian government is working on ways to use biofuel in the aviation sector; Transport Minister Nitin Gadkari said Monday that a Cabinet note would be moved on a “special policy” in this regard.