When U2 burst onto the stage in Sydney tonight, most likely opening with a brash version of Vertigo, it would be easy to assume the band are going through the motions.

After all, the Australian leg of U2's tour is the final segment of a worldwide juggernaut that has already taken in three continents and about four million fans.

Not to mention the Australian shows were postponed in March, making it more than 18 months since the Irish supergroup first stepped onstage to perform the Vertigo shows.

But Bono says the rescheduled tour represents an unusually short burst of touring for U2, with concerts limited to the Asia-Pacific. He believes the band has a sense of renewal and enthusiasm they haven't felt for some time.

"I'm very happy to be here, I'm excited," Bono says.

"It couldn't be better, because it's like going out on tour but you're not looking at a 12-month stretch and we're not at the end of a 10-month stretch. This is going to be unique unto itself."

Bono reckons returning to U2 duties is like going back to school after the holidays, hinting at a much-improved mood among the band members, including guitarist the Edge, whose daughter was believed to be suffering from a serious illness in March when the Australian tour was postponed.

"I always enjoy the school holidays because when you come back to school, you see people in a different light, you always do," Bono says. "You have a new best friend. And different things turn you on."

Now it appears the Edge and Bono couldn't be closer, despite a relationship which is occasionally turbulent. The Edge, with his cool head and studied creativity, has long been referred to as the band's "scientist", while Bono is proudly the charismatic class clown.

The Vertigo production has been put together by Bono's close friend Willie Williams, who designed U2's groundbreaking ZooTV tour in the early 1990s. This time he's presenting a full-scale live experience inside Telstra Stadium.

With towering video screens, piles of red-and-black speakers to match Vertigo's colour scheme and a surprisingly steep U-shaped stage, U2 are trying to get as close to fans as possible, without Bono physically launching himself into the crowd, which he was famous for in the band's younger days.

Since the big-haired high school students from working-class Dublin formed U2 in the late '70s, Bono has evolved into not only a rock star but also "Saint Bono", the political activist.

The contrast between being a "spoilt rotten rock star" - as Bono cheerfully describes it - and an anti-poverty campaigner is too much for some critics, although U2's fanbase doesn't seem to mind.

The frontman says the entire band have had to cop criticism for his charity efforts but he thinks it would be even worse if they didn't own up to their own luxurious life as mega-rich musicians.

During the Australian tour, U2 are flying between cities on a private jet, painted with the Vertigo logo. Backstage, the band have a range of private rooms including the "U2 Quiet Room" and dining room.

Then there's the legion of loyal U2 staff travelling with them in Australia - during our chat, a man pops his head into the dressing room to see if he can charge up Bono's mobile phone.

At the mention of criticism from some quarters, Bono simply shrugs his shoulders.

"Was it Russell Simmons, the godfather of hip-hop, who said, 'You can't help the poor if you are one'?¿" Bono says. "I wouldn't be so smart-arsed about it, but there is a sort of Catholic guilt that comes with making a few bob.

"I tell you what would be even more insufferable - can you imagine if I publicly gave all my money away? They would just hang me from the gallows. They would just say, 'Get on the f---ing donkey and this way to crucifixion.' I think actually people like the fact that we own up to living it large."

U2 reunited in the studio last month to record a new song, Window in the Skies. It's one of two bonus tracks on a compilation album, U218, which they're releasing this month.

Sydney fans may be among the first to hear the song performed live when U2 play tonight.

"Have you heard Window in the Skies?" Bono says. "Wow, that's a big song.

"We went into Abbey Road where the Beatles recorded their best work, where Pink Floyd recorded Dark Side of the Moon, where Radiohead recorded The Bends. I'd been in there but we'd never recorded there. Really, we recorded in what's a rehearsal room but we were in a very heightened state from being in this holy place."

The other bonus track on U218 is The Saints Are Coming. It was recorded with Billie Joe Armstrong from Green Day for the Edge's charity Music Rising, which helps jazz and blues musicians affected by Hurricane Katrina in New Orleans.

The clip for the track has already been viewed widely on the internet, to the delight of Bono.

"A million people have watched that on YouTube," he says. "Edge led the way on that project, he's doing amazing stuff. I thought it was a really inspired idea. He was probably making a point, as well: 'This is a music thing, it's called music, Bono!' "

U2
Tonight, Saturday and Monday, 5.30pm, Telstra Stadium, Sydney Olympic Park, 132 849, $63.50-$203.50.
U218 will be released on November 18.

(c) Sydney Morning Herald, 2006.