Beyoncé has announced she is giving away free concert tickets for life to one lucky fan, so long as they adopt a vegan lifestyle.

The superstar singer and her husband Jay-Z had previously challenged fans to become more plant-based and now it appears the couple are trying to use their fame to offer a unique reward for those who do.

In a post on Instagram, the 37-year-old attached a link to a website called 'The Greenprint', which tries to explain the "positive impact we can have on the world by eating plant-based meals".

The Greenprint challenges fans to share their own type of plant-based lifestyle

The site outlines the benefits that eating more plants can have on the wider world and encourages users to share how their diet affects the planet - ranging between plants for every meal to just plant-based at work.

Beyoncé herself appears to be adopting meatless Mondays and plant-based breakfasts but just choosing any of the options is enough to get an entry into the prize draw.

The Grand Prize winner will get two tickets for each Beyoncé and/or Jay-Z tour for a maximum of 30 years, with the total prize worth up to $12,000.

JAY Z and Beyonce perform on their On The Run Tour

Unfortunately the competition is only open to US citizens with a winner to be announced on May 22.

Written by the pair's personal trainer, Marco Borges, the Greenprint book purports to be a revolutionary new lifestyle and features an introduction by Beyoncé and Jay-Z themselves.

The website shows a sliding scale of how going vegan can impact the world, including a number of lofty goals.

By eating 10 plant-based meals, you're told you could have the environmental impact equivalent to 16 trees absorbing harmful gases from the air in a month or to fill 268 pitchers of water for a family in India.

At the other end of the scale, ten years of it could cut carbon emissions enough to power two shelters in Haiti for a year.