Google has announced the winners of this years Google Science Fair, an annual, worldwide science and technology competition for 13-18 year olds. This year's Grand Prize winner is a project that used bacteria to speed up the germination process of certain crops.

Ireland's Ciara Judge, Émer Hickey and Sophie Healy-Thow carried out a study into the effects of the Diazotroph family of bacteria, which occur naturally in soil. They found that it could reduce the germination time of certain crops, such as barley and oats, by up to 50 percent. In showing this, the girls, all 16, have found a potentially significant means of combating the growing global food challenge and reducing the amount of fertilizer needed for crop growth.

In recognition of their work, Judge, Hickey and Healy-Thow will each receive a 10-day trip to the Galapagos Islands, a US$50,000 scholarship from Google, a personalized LEGO prize and the chance to participate in astronaut training at the Virgin Galactic Spaceport.

Elsewhere, the winner of the 13-14 age was Mihir Garimella from the US, who built a flying robot inspired by the way fruit flies detect and respond to threats. Garimella built a sensor module with two infrared distance sensors, which uses algorithms to model the trajectory of and escape from approaching threats.

Judge, Hickey and Healy-Thow also won the 15-16 age group, and the 17-18 age group was won by Canada's Hayley Todesco. Todesco found a way to break down naphthenic acids using novel sand bioreactors. Using these bioreactors, she found it was possible to reduce acid concentrations and large biofilms four times for efficiently than by using batch bioreactor controls. The work could help to clean up waste from polluted oil sands.

The Scientific American Science in Action award was awarded to Kenneth Shinozuka for his work with wearable sensors to help those living with Alzheimer's and the Voter’s Choice award went to Arsh Dilbagi for his project Talk, which allows those with speech difficulties to communicate using their breath as a device controller.

The Google Science Fair has been running since 2011. Submissions have included an octupus-inspired propulsion system and a flashlight powered by body heat.

The video below provides an overview of the winning project.