A fleet of electric buses owned by a Transport NSW contractor has been pictured being charged by diesel generators, raising questions about the state government’s transition to green energy.

About 15 of the U-Go Mobility buses were seen powering up at a depot in Marrickville, 2GB Sydney reported this afternoon.

“If you’re plugging a bus into a diesel generator, it’s completely pointless,” host Clinton Maynard said.

Acting coordinator general Barbara Wise has set the record straight, saying the fleet was fast-tracked to soothe bus shortages in the city’s north and are replacing trains while the government converts the South West link to a Metro service.

“Because these buses are only there temporarily, it didn’t make sense to spend a lot of taxpayer’s money to upgrade that depot to full electric, because we’ll end up moving those buses probably in the next nine to 12 months to an electrified depot,” she told 2GB.

The NSW government currently has more than 8000 diesel and gas-powered public transport buses on the roads.

The state has invested in its multi-billion-dollar program to transition the fleet to zero emissions technology in the hope of achieving net-zero emissions by 2050.

Greater Sydney is set to reach the target by 2035, outer metropolitan regions by 2040 and regional NSW by 2047.

In December, the government purchased 319 new zero-emissions buses and plans to purchase 1000 more by 2027.