Airplanes

Airplanes

Project Drawdown defines the airplanes solution as: the increased use of technologies to reduce aircraft fuel burn. This solution replaces conventional aircraft with existing global fleet-wide fuel efficiency.

Air travel is estimated to cause approximately 2.42 percent of manmade carbon dioxide emissions in the world (BDL, 2014). However, its expansion is causing increasing alarm. Airplane fuel efficiency efforts aim to reduce fuel use per passenger-kilometer of air travel. Though freight-only aircraft fuel efficiency is not analyzed here, part of the impact on air freight fuel use is accounted for in the large fraction of total air freight that is carried in the belly of passenger aircraft. [1]

As there are numerous technologies and operational approaches for reducing airplane fuel use, only the most impactful technologies in use today to improve fuel efficiency were included in this study. Therefore, well-publicized but non-commercial technologies such as aviation biofuels were excluded.

Methodology

This analysis includes the newest, most fuel-efficient aircraft (called “intermediate generation”), [2] as well as the use of fuel efficiency retrofits to existing aircraft. Intermediate generation aircraft are expected to be 15-20 percent more fuel-efficient than earlier models, in part as a result of more fuel-efficient engines, new wingtip devices, [3] and light weighting approaches. Research suggests that the combination of these three technologies in a retrofit would amount to efficiency improvements comparable to a newer aircraft model. In this study, new and retrofitted aircraft are compared to conventional aircraft with the existing global fleet-wide fuel efficiency.

Total Addressable Market [4]

The total addressable market for airplanes is measured in terms of total interurban passenger travel by air, projected for every year of analysis (2020-2050), in billion passenger-kilometers. Current adoption [5] was taken as the total passenger-kilometers provided by existing intermediate generation aircraft, in the single-aisle and twin-aisle categories.

Projected adoption of fuel-efficient aircraft was based on the expected production of intermediate generation aircraft, according to published delivery rates of major suppliers. [6] Delivery rates were assumed fixed for each aircraft type.

Adoption Scenarios [7]

Impacts of increased adoption of airplanes from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the existing fraction of higher-efficiency aircraft remains constant.

• Plausible Scenario: Fuel burn is improved by 15 percent, Boeing and Airbus supply aircraft at their published rates, and aircraft older than 24 years are retired.
• Drawdown Scenario: Aircraft delivery rates and retirement remain the same as in the Plausible Scenario. However, a third supplier is included that produces new, comparable single-aisle aircraft by 2025 and twin-aisle aircraft by 2035. [8] Additionally, fifty aircraft are retrofitted annually.
• Optimum Scenario: This scenario differs from the Drawdown Scenario in only two key ways: 1) efficient aircraft are assumed to take more passengers (a higher load factor of 90 percent, compared to 80 percent in other scenarios); 2) fuel burn is reduced by 18.3 percent. Everything else remains the same as in the Drawdown Scenario, including the existence of an additional supplier.

Emissions Model

Emissions for each scenario were estimated using the fuel emissions factor taken from the Intergovernmental Panel on Climate Change (IPCC) guidelines, and applied to fuel consumption data from the International Council on Clean Transport (ICCT).

Financial Model

Costs of adopting the intermediate generation aircraft are reported as the additional cost compared to adopting aircraft with average fleet efficiency. For each intermediate generation aircraft, an equivalent conventional aircraft was priced and the price difference was derived. [9] The average difference for single-aisle aircraft was around US$11 million, [10] and that of twin-aisle was US$40 million. [11] Operating costs, which included fuel costs, were derived using historical data from the International Energy Agency (IEA). [12] The solution’s operating costs were reduced by the efficiency improvements noted above.

Integration [13]

To prevent double-counting, steps were taken to ensure that the total travel demand of all non-urban passenger Transport Sector solutions remained below the projected total non-urban travel demand.

Results

In the Plausible Scenario, a potential reduction of 5.05 gigatons of carbon dioxide-equivalent greenhouse gas was found from 2020-2050, which corresponds to a 63 percent adoption rate by 2050. Net costs over that time would be US$662 billion above the conventional approach. Efficiency improvements are estimated to bring operating savings of US$3.2 trillion, however. For the Drawdown Scenario, the emissions avoided amounted to 5.2 gigatons with 80 percent adoption; the Optimum Scenario would result in 6.5 gigatons of emissions reduced.

Discussion

The use of more efficient aircraft is desirable for airlines in times of higher fuel prices. It would have direct bottom-line impacts, as fuel often represents a third of operating costs. For much of 2016, however, fuel prices were low, and there is no assurance that prices will return to their previous levels of almost three times higher. Nevertheless, Project Drawdown’s calculations indicate a large buffer in operating savings and marginal costs that make the investment in fuel-efficient aircraft financially viable for airlines at lower fuel prices. Using Jet A fuel prices of March, 2017, the operating savings are still high at US$1.2 trillion for the Plausible Scenario.

Limitations

There are limitations to this approach. For example, the potential of other technologies being implemented was excluded in this study. [14] Also, the Reference Scenario conservatively assumes fixed fleet efficiency. These limiting assumptions were made to show the impact of existing technologies on the airline industry. The results indicate that airlines have a role to play in the planet reaching the point of drawdown.