Rolls-Royce says the hybrid-electric propulsion system it is developing for possible use on future regional airliners has achieved a key milestone of generating more than a megawatt (1 MW) of power in ground tests. Earlier this year, the UK-based aircraft engines manufacturer started testing the Power Generation System 1 (PGS1) with the goal of generating 2.5 MW, with further tests set to continue at the company’s renovated Testbed 108 facility in Bristol, UK.

The generator, which Rolls-Royce says is about the size of a beer keg, incorporates one of the group’s AE2100 turbofan engines, as well as special controls and a thermal management system. According to the company, the 1MW power generated in tests so far is sufficient to continuously power around 1,000 homes.

“When future hybrid-electric aircraft opportunities emerge in the megawatt-and-above class, we want to be as prepared as we can be to offer a ready-made solution,” said Adam Newman, Rolls-Royce’s chief project engineer for aviation futures.

For the latest tests, the company has combined a generator with a 3,000-volt power electronics system that it has been testing at its facility in Trondheim, Norway. The work in the UK has received financial support from that country’s Aerospace Technology Institute’s MegaFlight program, while the Trondheim project has been supported by the European Union’s CleanSky 2 fund.

The PG21 generator technology could be used in hybrid-electric propulsion systems or as part of a “more-electric” system for larger aircraft. Rolls-Royce said PGS1 forms an important part of its sustainability strategy, which includes developing innovative electrical power and propulsion systems, as well as further improving gas turbine performance and promoting the use of sustainable aviation fuels.