In November of 2011, American commercial airlines consumed 1.83 million litres of fuel — every day — and paid a total of $US49.8 billion that month to do so. And with increasingly tight operating budgets, fuel efficiency has quickly become a primary concern for the airlines. Boeing thinks one possible solution is its new plug-in hybrid jet concept that burns 70 per cent less gas per flight with the help of local power grid.
The hybrid electric design — dubbed the SUGAR Volt — has grown out of Boeing's SUGAR (Subsonic Ultra Green Aircraft Research) project to investigate and identify viable green jet technologies that can be developed by 2050 and is funded by a NASA contract. Other design variations are looking into using hydrogen or methane-based fuel cells as potential green power supplies.
The Volt, however, appears to be the most practical system to emerge from Boeing's research, functioning much like the Holden Volt or the plug-in Prius do. Every time it's at the gate, the Volt will draw electricity from the airport's power grid, charging an array of batteries stored in the belly of the plane. Dual-turbine engines would be powered by traditional jet fuel for takeoff, but once the Volt reaches cruising altitude, the system will switch over to electrical power for the majority of the flight. Not only does this result in zero emissions for most of the trip, it requires just 30 per cent of the fuel that a conventionally-powered plane would need and effectively double the operational range of the airliners. What's more, the plane's wingspan is expected to measure double that of current commercial models, which increases energy efficiency and allows for shorter takeoffs.
There's a reason why the SUGAR Volt isn't coming out until 2030, however, and it has nothing to do with Chevrolet's licencing agreements. As usual, it's the current state of battery technology that's holding up development. As Boeing researcher Marty Bradley explains, battery technology "needs to improve many, many times over what we have today. Battery technology is being worked around the world, especially in the auto and electronics industries. We need to leverage that work to see if we can get the improvement we need in an aviation compatible package." This is partly why the Volt will have such a massive wingspan — to offset the expected mass of all those batteries. And even if the Volt itself never flies, you can be sure that the systems developed from this project will.