Aviation is often portrayed as a villian in the battle to reduce the emissions of greenhouse gases. It currently accounts for about 3% of greenhouse gas emissions in the European Union. That’s about as much as the estimates of computer equipment’s carbon footprint. So why all the fuss?
The problem with aviation is twofold. Firstly, it one of the only areas where emissions are predicted to rise. Much of the blame for this is being laid at the door of the low-cost airlines, who have made flying cheaper and more popular. The aviation sector has seen an 87% increase in carbon dioxide emissions since 1990, with an increase of as much as 25% being predicted for the future.
Secondly, the greenhouse gas emissions from aircraft might be more damaging than other emissions. The Intergovernmental Panel on Climate Change (IPCC) carried on research on the subject. It found that the aerosols in jet engine exhausts had a range of additional negative impacts at high altitude. For example, the contrails and aerosols could alter the properties of clouds, thereby depleting protective ozone in the stratosphere.
It’s thought that aircraft emissions potentially cause two to four times the global warming effect of carbon dioxide produced on the ground.
Campaigners want us to take fewer flights, particularly short-haul ones. The economic downturn is proving their ally. 4.6 million fewer people flew through British airports in 2008 than the year before. This is the first reduction in passenger numbers since 1991. Airports with a large number of budget airline flights faired the worst.
London Stansted’s passenger numbers were 6% lower than the previous year, whilst London Gatwick’s dropped by 2.8%.
Also, a large number of airlines including XL, Zoom and Silverjet went bankrupt in 2008, further` reducing passenger numbers.
However, as economies recover, the demand for air travel is likely to increase. In particular, demand is likely to come from India and China as air travel becomes more affordable.
The aviation industry is not ignoring environmental concerns. The Director-General of the International Air Transport Association, Giovanni Bisignani, pointed out that over the past thirty years, aircraft noise had been reduced by three quarters and fuel efficiency had increased by 70% over the last 40 years. But he admits that current levels of greenhouse gas emissions are ‘politically unacceptable’.
The aircraft themselves are changing. Some changes are small but effective. Have you noticed the little winglets on the edges of many modern airliners? They increase lift and reduce drag. Both Boeing and Airbus have research programmes to increase the efficiency of winglets, with Boeing already filing patents for winglets with variable geometry.
Aviation Partners, a company that specializes in making these devices, says that by 2014, winglets will have saved five billion gallons of fuel!
The use of composite materials, that reduce weight and therefore need less power to lift, is increasing. The latest Boeing 787 Dreamliner is being made completely out of composites and should be 20% more efficient than the aircraft it replaces.
We might also see more aircraft unpainted: paint adds five hundred pounds in weight.
Inside the aircraft, fuel efficiency is being increased with advanced avionics and simple measures like cutting the weight of the service trolleys.
The new, larger aircraft capable of carrying more passengers, like the Airbus A380 and next generation Boeing 747, reduce the amount of greenhouse gases produced per passenger mile. Also we’re seeing long-haul, high capacity aircraft with only two, more economical, engines, such as the Airbus A330 and the Boeing 777.
Much fuel is wasted by aircraft being held in holding patterns before beng allowed to land. More efficient air traffic control with reduced taxi times, slower flying speeds and and more direct routes could all increase fuel efficiency. It’s estimated that if Europe had one single air traffic control authority, aircraft fuel consumption could be reduced by 12%.
But what of developments for the future? Hydrogen power for aircraft is likely to remain on the drawing board for many years to come.
Fossil fuels are likely to power aircraft for the foreseeable future. However, the use of biofuels is being developed. Sir Richard Branson, head of Virgin Atlantic, has set up a company to develop more environmentally-friendly aviation fuels.
In February 2008, a Virgin Atlantic Boeing 747 flew from London Heathrow to Amsterdam Schipol using a fuel extracted from a mixture of coconuts and Brazilian babassu nuts. Both these nuts do not compete with staple food sources and came from mature plantations. However, at high altitudes this biofuel is likely to freeze.
The competitions held by the X Prize organization have already been responsible for big leaps in technically-difficult areas such as space travel and self-driving vehicles. It’s just received funding for a competition to produce an aviation-grade biofuel.
But environmental groups have claimed that aviation biofuels are not the answer. Dr Doug Parr, Greenpeace’s chief scientist, said that less air travel was the only answer and labelled Virgin’s flight as ‘high-altitude greenwash’.
In the future, aircraft may even be nuclear-powered, just like Thunderbirds, the cult ’60s TV series. The US had a test programme in the 1950′s, but the concept of nuclear-powered bombers became redundant with the introduction of intercontinental ballistic missiles.
Ian Poll. Professor of Aerospace Engineering at Cranfield University has called for a government-funded research programme to examine the feasibility of nuclear-powered aircraft. All we need now is Thunderbirds’ resident genius, Brains, to invent them!
