Currently, an estimated 20,000 aircraft ferry 3 billion passengers around the world in a year. In 20 years, more than 50,000 planes and many more passengers are expected to fly. With this volume of air travel, jet emissions add fuel to the already burning problem of global warming and climate change.
According to the International Air Transport Association, the global airlines’ body, the aviation industry contributes to 2 per cent of the total global greenhouse gas emissions. It has set out a target for 1 billion passengers to fly on using a mix of clean energy and fossil fuels, by 2025.
The global aviation industry has been experimenting with biofuel for some time now. So far, more than 5000 commercial flights have been operated across the world using biofuels. 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 2011, Alaska Airlines operated 75 selected flights on a cooking oil blend, while Dutch Airline KLM flew weekly biofuel flights between New York and Amsterdam for six months in 2013. Last year, Australian flag carrier Qantas operated a 15-hour flight from Los Angeles to Melbourne using a blended fuel that was 10 per cent derived from an industrial variety of mustard.
Bombardier Q400, India’s first ever partially biojet fuel-powered aircraft, took off on August 27, 2018 from Dehradun and landed at the Delhi airport after a 45-minute flight.
The 72-seater SpiceJet flight, which carried 28 people including 5 crew members, had its engine fueled with 75 per cent aviation turbine fuel (ATF) and 25 per cent biojet fuel. The biofuel was a mix of oil extracted from the seeds of Jatropha plant sourced from Chhattisgarh. Five hundred farmer families were involved in the production of Jatropha, a tropical drought-resistant, oil-rich flowering plant. The CSIR- Indian Institute of Petroleum (IIP), Dehradun prepared 330 kg of biofuel especially for the pilot project. A key advantage of this biofuel is that it is of the ‘drop-in’ variety. i.e., it can be used in existing aircrafts without any engine modifications.
The biofuel was first tested on a 20-minute flight with crew only, a day before the maiden flight. The flight result showed that biofuel had 1.8 per cent higher energy density than regular ATF. The advantage of using biojet fuel as compared to ATF is that it reduces carbon emissions and enhances fuel efficiency. It has the potential to reduce dependence on traditional aviation fuel by up to 50 per cent on every flight and thereby bring down air fares.
Biojet fuels are fuels derived from renewable bio-resources, which are used for aircraft. It is mostly carbon-neutral and can be prepared partially from renewable resources such as agricultural wastes and residues, biomass, non-edible oils, animal fat, vegetable oils, natural gas and bio-degradable fractions of industrial and municipal wastes. Biojet fuels generate the same amount of power as regular fuels and dissipate less heat and hence, are cheaper than regular fuel.
Biojet fuels will benefit farmers by giving a boost to agriculture. They reduce stress on the extraction of fossil fuels and provide alternative sustainable and clean energy methods. Further, it reduces dependence and imports by non-oil producing nations. Biofuel flights could make air travel cleaner and more efficient, thus drastically reducing the cost of airline operations and reducing the dependency on ATF.
Extensive use of biofuel for regular flights appear distant. The bio-oil concentration can only rise up to 50 per cent, beyond which, the combustibility of the fuel can be impacted.
An international research programme led by NASA reported that the use of biofuels can reduce particle emissions in the jet exhaust by 50-70 per cent. On the flip side, lifecycle assessment by the Yale School of Forestry found that the use of biofuels could reduce greenhouse gas emission by up to 85 per cent or increase them by 60 per cent, depending on the circumstances under which it is produced.
The infrastructure to mass-produce biojet fuel and deliver at airports is expensive. Fuel companies are still working out sustainable ways to manufacture biofuel for aircraft. 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. On the other hand, second-generation fuels posed greater extraction challenges.
As technology improves, there may be possibilities of having flawless alternative energy methods, which could pave the way to a cleaner environment all over again.