Electric green taxiing systems (EGTS) have emerged as a beacon of hope for reducing fuel consumption and emissions in the aviation industry. The idea is simple, use electric motors in the wheels to taxi airplanes instead of relying on the fuel guzzling main engines. 

Despite many successful demonstrations, widespread adoption of EGTS has yet to take off. Why?
 

The Economic Hurdle

While the environmental benefits that EGTS provides are absolute, airlines are still businesses, and cost plays a major role in their decision making. Installing an EGTS system adds significant weight to the aircraft. This extra weight translates to carrying less fuel, cargo or passengers, which negates some of the fuel savings seen with EGTS during taxiing on the ground. This is especially the case for longer flights.

Furthermore, the upfront cost of purchasing and installing an EGTS system can be quite substantial. Airlines, particularly budget carriers, are often hesitant to invest in new technologies without a clear and immediate return on investment. While some companies propose leasing models to address this, widespread adoption requires a compelling economic case.
 

Balancing Efficiency

There are two main approaches to EGTS design: systems powering the nose wheel of an aircraft, and systems that power the main landing gear. 

Nosewheel-based systems are simpler to install, but have limitations. The turning radius of wheels equipped with EGTS are restricted by the maximum steering angle. This means that undergoing tight maneuvering on busy airport grounds will be challenging, especially for larger aircraft.
 

Main landing gear-based systems offer better maneuverability for aircraft, but require more complex engineering and integration with the existing landing gear systems. This adds to the cost and development time of such systems.

Another factor to consider is the evolution of aircraft themselves. Modern airplanes, particularly single-aisle models like the Airbus A320, are becoming increasingly fuel-efficient. 

This reduces the overall benefit of EGTS on newer aircraft types. Additionally, the trend towards longer-range, single-aisle aircraft further diminishes the appeal of EGTS, as the weight of such a system is of higher significance on longer flights.

This does not mean EGTS cannot find a niche in the aviation market. Older, less fuel-efficient aircraft could benefit more from electric taxiing due to their (relative) inefficiency. Additionally, airports with significant taxi times due to congestion could see a greater reduction in fuel burn and emissions with widespread EGTS adoption.

The Future of Electric Taxiing

The future of ETS likely lies in its integration with the next generation of aircraft. Designing these systems as part of the overall aircraft architecture from the beginning could address weight and cost concerns. Additionally, advancements in battery technology could offer lighter and more powerful options for powering the electric motors of an EGTS system.
 

Furthermore, as environmental regulations tighten and the pressure to reduce emissions intensifies, the economic argument for EGTS could become more compelling. 

Collaboration between airlines, manufacturers, and regulatory bodies will be crucial in pushing this technology forward.
 

Electric taxiing systems offer a promising solution for reducing fuel consumption and emissions during aircraft ground operations. However, the economic realities, technical limitations, and evolution of aircraft design have hindered the widespread adoption of EGTS systems. 
 

Nevertheless, EGTS  could still find a niche in the widespread aviation market and potentially become a stepping stone towards more advanced electric or hybrid propulsion systems for future aircraft.  

The path forward will likely involve technological advancements, a shift in economic considerations, and a collaborative effort from various major stakeholders in the aviation industry.