For A Greener Future

It is heartening to note that with passenger numbers growing at an average of five per cent per annum, aviation has managed to decouple its emissions growth to around three per cent or 20 million tonnes annually. This has been achieved through massive investment in new technology and operating procedures.

It is interesting that while people can immediately see the effects of vehicles on air pollution, they do not readily perceive the contribution of high-flying airplanes to climate change. Although aviation is a relatively small contributor to climate change accounting for a mere two per cent of the world’s carbon dioxide emissions (the main cause of global warming), its share is likely to increase given the sustained growth of the aviation industry.

The principal greenhouse gas (GHG) released from powered aircraft is carbon dioxide. Other emissions include nitric oxide and nitrogen dioxide, together termed oxides of nitrogen or NOx, water vapour and particulates, sulfur oxides, carbon monoxide which bonds with oxygen to become carbon dioxide immediately upon release, incompletely burned hydrocarbons, tetraethyl lead, and radicals such as hydroxyl. The UN Inter-governmental Panel on Climate Change (IPCC) has estimated that the total impact of aviation on climate is about two to four times that of its direct carbon dioxide emissions alone excluding the potential impact of cirrus cloud enhancement. As aviation grows to meet increasing demand, the IPCC forecasts that its share of global manmade carbon dioxide emissions will increase to around three per cent by 2050. It is heartening to note that with passenger numbers growing at an average of five per cent per annum, aviation has managed to decouple its emissions growth to around three per cent or 20 million tonnes annually. This has been achieved through massive investment in new technology and operating procedures.

Concerted Initiative by Aviation Industry

The global aero engine market is estimated to touch $37.2 billion ( Rs. 2,23,200 crore) by 2020 with a compound annual growth rate (CAGR) of six per cent over the next eight years. This is one industry that responded early enough to the need for becoming more environment-friendly. Since 2005 there has been pressure from the European Union Emissions Trading Scheme (EU-ETS) a capand-trade scheme operational in the EU that has one allowance representing one tonne of carbon dioxide. It operates through the allocation and trading of emission allowances. The aim of the EUETS is to reduce emissions in a cost-effective manner, allowing companies to trade emission allowances and thereby determine how and where they reduce emissions. Original equipment manufacturers (OEMs) and operators have to grapple with high fuel costs and thus support the need to reduce operating costs and increase fuel efficiency.

It is instructive to note the work done by bodies like EnviroAero, established by the commercial aviation industry body, the Air Transport Action Group (ATAG). The ATAG is the only global association representing all sectors of the air transport industry with a mission to promote sustainable growth of the aviation industry. Sustainable Aviation UK, for instance, has provided a platform for industry and environmentalists to collaborate on solutions. Significantly, it was at ATAG’s global Aviation and Environment Summit in Geneva in 2008 that commercial aviation industry leaders signed a declaration on climate change aimed at carbon-neutral growth and a totally sustainable industry. The meet brought together all sectors of commercial aviation, aircraft manufacturers, airlines, airports, air traffic control and engine manufacturers. It was the first time the industry came together. The declaration outlined aviation’s concept of ‘carbon-neutral growth’ with an aspirational goal of carbon-free flight.

The impact of the US Continuous Lower Emissions, Energy and Noise (CLEEN) programme under the Federal Aviation Administration (FAA) also merits mention. Selected by the FAA as partners to participate in CLEEN programme through a costsharing arrangement, these companies have been working to develop technologies to reduce noise, emissions and fuel-burn as also enable the aviation industry to expedite integration of these technologies into current and future aircraft from 2015-18. Under the CLEEN programme, the FAA entered into a five-year agreement with Boeing, General Electric (GE), Honeywell, Pratt & Whitney (P&W) and Rolls-Royce. These partner companies are working towards FAA’s commitment to implement Next Generation Air Transport System (NextGen). Significantly, over this period, the FAA envisages an investment of $125 million ( Rs. 750 crore). With the funding match from the five companies, the total investment value is estimated to exceed $250 million ( Rs. 1,500 crore). Innovations by several manufacturers to lower emissions inspired by this initiative are as follows:

Pratt & Whitney

The company’s PurePower geared turbofan (GTF) engines claim higher fuel efficiency, better fuel-burn and environmental benefits, in addition to reduced life-cycle costs. A GTF engine operates through a combination of a large quiet fan and a fast and efficient turbine. In 1998, after discontinuing its upgraded PW800 where the fan section was replaced with a gear system and new single-stage fan, the company reverted to using the PW6000 turbo machinery with a new gearbox and a single-stage fan. This then evolved into the GTF programme and in July 2008, the GTF was renamed PW1000G. This engine was tested on the Boeing 747SP with the second phase of flight testing on Airbus A-340-600. Compared to conventional engines, P&W claims the PurePower engine is a leapfrog technology and can provide up to 16 per cent improvement in carbon emissions. In addition to lower maintenance costs, the noise level of the PW1000G GTF engine compared to other similar engines is 50 per cent lower. PurePower has now been selected to power the Bombardier CSeries, Mitsubishi Regional Jet, Embraer’s second generation E-Jets, option on the Irkut MS-21 and Airbus A320neo.

The company calls its PurePower PW1100G-JM its ‘greenest engine’ and is scheduled for introduction by Airbus on its “neo” series of short- to medium-range, narrow-body aircraft in 2015. These engines will be operational in India’s most profitable lowcost carrier IndiGo’s A-320neo in 2015.

CFM International

CFM International, a joint venture between GE and Safran, has announced a new LEAP-X engine for the A-320neo and other single-aisle airliners. As against the traditional all-metal ones, the innovative engine has a lightweight fan blade made of woven carbon fibres that help reduce the weight of the aircraft by 1,000 pounds. The company claims that LEAP-X will effect double-digit improvement in carbon dioxide emissions and noise levels in addition to reducing NOx emissions by 50 per cent. In an emerging competitive market, CFM recently expanded the LEAP-X engine’s turbofan diameter by two inches to improve fuelburn, putting it on an equal footing with the PW1100G PurePower.

Rolls-Royce

The Trent family of products is the company’s predominant offering in terms of environmental regulatory compliance. The Trent-900 engine uses a 116-inch swept fan, a low NOx combustor and a contra-rotating high-pressure system which minimises emissions, noise and fuel consumption, and make the Trent-900 the most environment-friendly engine powering the Airbus A380. According to Rolls-Royce, the Trent XWB is the most efficient large jet engine which will help reduce jet emissions by 16 per cent. It received 1,100 advance orders for the engine in 2012. Tests are on and it will enter service in 2014.

Stating its commitment to meeting environmental challenges, Rolls-Royce has set aggressive targets based on the goals of the Advisory Council for Aeronautical Research in Europe (ACARE). According to the company website, the ‘Phase 5’ style of low emissions combustor is present in all civil production engines and has helped to cut NOx emissions to best-in-class levels on the Trent family. Ongoing R&D in the affordable near term low emission (ANTLE) demonstrator engine with new lean burn combustion system aims to reduce engine NOx emission further.

Honeywell

In 2011, Honeywell delivered the latest version of its HTF7000 family of engines, the HTF7500E, to Embraer, for flight testing on its family of Legacy 450 and 500 series jets. Honeywell is also incorporating its green combustor technology called singular annular combustor for emissions reduction (SABER), into its HTF7000 family, helping both OEMs and operators reduce carbon dioxide, nitrous oxide and other unburned hydrocarbon emissions while lowering operating costs.

The company says a second-generation low-emission upgrade for the HT7000-series engines could be available as a retrofit option within a “couple of years” if planned durability tests on the company’s Tech7000 technology demonstrator engine prove that the product is ready. Called SABER-2, the technology combines changes to the combustor, fuel nozzles and fuel scheduling to reduce NOx emissions beyond the 25 per cent cut provided by today’s SABER 1 technology in all new HTF-family engines, including the HTF7250G for the Gulfstream G-280 and the HTF7500E for the Embraer Legacy 450 and 500. SABER-1 can also be retrofitted into HTF7000 engines on Bombardier’s Challenger-300.

Designed to address environmental issues and help operators gain overall business efficiencies, Honeywell’s SABER combustor has begun shipping with OEM engines. Also, Honeywell’s HFT7250G engine, a derivative of the HTF7000 engine, has been designed to significantly reduce emissions and noise signatures. Honeywell’s engineers are also experimenting with third-generation SABER technologies that are seen as “the next breakthrough” in emissions reductions. SABER-3 will see a more radical aerodynamic design of the combustor to lower NOx levels further.

What Lies Ahead?

IPCC estimates that aviation’s contribution to climate change could grow to five per cent by 2050 if action is not taken to control emissions. On a positive note, modern jet aircraft today are significantly more fuel-efficient, with lower carbon dioxide emissions than 30 years ago.

The demand for lightweight, energy-efficient, low-emission aero engines is expected to drive future market growth. Alternative fuels are also being explored. Though biofuels blended with traditional jet fuel were cleared for use in 2011, limited supply and high cost has restricted its immediate adoption. Companies like Virgin Fuels and GE Aviation are conducting research on biofuel technology for use in jet aircraft. Experts note that if biofuels prove to be economically viable, aero-engine design too will undergo major changes.