Landing a new role in power generation

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Aircraft landing on runways across the UK could feed electricity into the National Grid by converting braking energy into electricity.

The long-term concept is the centrepiece of a £160,597 EPSRC-sponsored feasibility study involving academics from Liverpool, Lincoln and Loughborough universities, plus industrial partner EADS UK. Initial results of the research are expected in October this year.

The inventor of the ambitious concept Qing-Chang Zhong, an electrical engineer from Liverpool University, proposes that once aeroplanes touch down on the runway they would catch up with and attach to a moving platform — the parking vehicle — equipped with energised coils in its wheels.

The inertia of the rolling aircraft would push the parking vehicle forward and the electricity generated in the coils would be processed by a power conditioning and control system on the ground.

Zhong envisions parking vehicles would be connected — like a tramcar — to low-lying electrical wires on the side of the runway so that the generated electricity could be fed into the grid after processing, essentially changing the aircraft/runway into a power generator.

He estimated that the average power dissipated during the 30 second landing of a 40-ton aircraft travelling at 150mph amounts to 3MW.

eathrow Airport, where an aircraft lands every two minutes, would give an average power source of 750kW.

Zhong said that the key enabler of this technology will be the parking vehicle, which must move down the runway ahead of the landing aeroplane at 150mph, the speed at which most aircraft travel when first touching down.

He admitted that such an untested concept raises many safety concerns that will need to be addressed in his feasibility study.

One of the top tasks, added Zhong, will be to identify an optimal topology for the energy-converting vehicle. There will also need to be a thorough assessment of the mechanical impact of it on the aircraft. Much of this impact could be alleviated by driving the vehicle at a similar speed to the aircraft, said Zhong.

Heathrow Airport could provide an average power source of 750kW

He added that the parking vehicle’s power system will be capable of getting it up to such great speed. ‘Once the aircraft attaches to the parking vehicle it will be changed to a generator,’ he said.

According to Zhong, if his mathematical models prove to be true, the energy recovered from the generator would far outweigh any energy exerted by the power system. However, a major challenge will be developing the right power conditioning methods and control system to process the electricity recovered from the landing aircraft before feeding to the grid. The electricity generated will have a variable voltage and frequency because the speed of the aircraft decreases as time passes. Also, the speed, mass and braking force of each aircraft are different.

Zhong said that aircraft land discontinuously, which means that the electricity generated is impulsive.

He has applied for a patent for his energy-recovering concept and is aware of a patent on only one other aircraft energy-recovery system.

Zhong said that particular system regenerates power back to the aircraft, but it requires an on-board installation. With Zhong’s concept, airport operators would be able to implement the technology without involvement of aircraft manufacturers and airlines.

The EPSRC study will primarily be conducted in simulation, however Zhong and his colleagues are expected to conduct basic experimentation to support and confirm the simulation results. A test rig is being set up at Liverpool University to verify the theory and technology for the power conditioning and control system.

If the study is successful, Zhong said he will be able to further develop his concept for more intensive lab tests, leading to a prototype.

Details of Qing-Chang-Zhong’s EPSRC grant can be read here: http://gow.epsrc.ac.uk/ViewGrant.aspx?GrantRef=EP/H004351/2