The world's biggest band have given their new album away for free on iTunes. But what's in it for them?

U2 sent shockwaves through the music industry last night by announcing at the launch of the new iPhone 6 that their new album 'Songs of Innocence' was to be given away completely free of charge on Apple's iTunes online music store.

To say that this is an unconventional method to release new material would be an understatement and it could potentially be seen as a seismic shift in the way music is delivered to its audience. Since the advent of iTunes and, more lately Spotify, the means by which people experience music has been subverted. Purists suggest that this is to the detriment to the concept of the album as a standalone collection of music, as today's listeners seem more content to download or stream a series of individual tracks as they grow their personally curated collections. It's the musical equivalent of separating the wheat from the chaff.

By partnering with Apple and giving their entire record away for free, U2 have embraced the digital age in a way that many of their contemporaries have appeared so hesitant to do and also encouraged fans to download and listen to the albums as a whole rather than to cherry-pick their way through it by downloading the odd single here or there.

But what exactly is in this for U2? Quite a lot, it turns out. Bono has said on many occasions, and as recently as last week, that he doesn't believe in "free" music so it would be naive to suggest that this is an entirely philanthropic gesture by U2. Various figures are traversing the internet this morning about exactly how much U2 will earn from their "free" album and it's entirely possible that this could generate Bono and co. more than any other album they've released in the last two decades.

The Wall Street Journal quotes a source "familiar with the talks" who said U2 were paid an astonishing $100 million for their participation, with Apple only too happy to realign with the group they previously worked with ten years ago to release a special U2 iPod. This move was also presumably designed to incentivise the purchase of U2's back catalogue in iTunes to a younger audience and to highlight ticket sales for the eventual tour on the back of 'Songs of Innocence' (though it's unlikely they would have needed to much help in that regard).

Jimmy Iovine, record producer and co-founder of Beats, explained Bono's intentions further to Time.

"The charts are broken", he said. "The old music industry has reached a low point and hasn't kept up with the digital world. He wants to see the artists' reach measured by how much they're listened to, by whatever medium or method."

U2 are following the lead of Beyonce, Jay Z and Radiohead who in the past have released music either unannounced, packaged with a tech company or free. In fact, Beyonce sold around 800,000 units of her last album within a week (though fans had to pay for it) when it was made instantly available on iTunes and U2 are expected to far eclipse that figure.

What can we take from this? It's a pretty strong indicator from U2 that they think the traditional means for music distribution is broken and what they have done with 'Songs of Innocence' is set a very appealing, if completely unsustainable, precedent. When the sales figures are released in a week or so we expect there'll be a few happy faces around the Vico Road but where does this leave the bands who are relying on album sales to generate income or recoup losses?

Releasing an album for free (or by having Apple write you a Euro Millions sized cheque) is a luxury only afforded to the 1%, leaving countless other bands trying to keep their balance on the shaky ground that is today's music industry.

When the world's biggest band acknowledges that the system in place to sell music to the public is broken, where does that leave the little guy? U2's free album will no doubt be a delight to many but it might just be the clearest indicator yet that the system we have in place is irreparably damaged.