Since 2011, Google has been challenging innovative teens aged 13-18 from all around the world, to use their technology and scientific know-how to transform the world into a better place. Contestants are categorized into three age categories (13-14, 15-16, 17-18) and five semi-finalists are selected from each. The fifteen youngsters are then flown to the company's headquarters in Mountain View, CA, to present their ideas to a group of judges, who select a winner from each category, one of whom is also declared the overall winner.

Natural Bacteria Combating World Hunger

This year's top prize, which was announced on September 22nd, went to a group of three 16-year-old girls from Ireland whose invention tackles one of the biggest issues facing our society - world hunger. Ciara Judge, Émer Hickey and Sophie Healy-Thow's project involves using a bacteria called Diazotroph that is naturally found in soil, to speed up the germination process of certain crops like barley and oats by as much as 50%. If deployed on a large scale this breakthrough has the potential to increase food yields substantially, and help alleviate the severe food shortage faced by some developing countries.

The young girls said that they thought of this idea after reading about the widespread famine in the Horn of Africa (Somalia, Ethiopia, Eritrea, Djibouti and Sudan), in 2011. In addition to the exciting prospect of saving the lives of millions of people, their innovation also won the trio a $50,000 scholarship from Google, a 10-day trip to the Galapagos Islands, and a chance to participate in astronaut training. Their high school also received a grant of $10,000 USD for science or computer equipment.

Fruit-Fly Inspired Flying Robots

Tiny robots that can be crucial allies in search and rescue missions following natural disasters, impressed the judges enough to win its inventor, Mihir Garmimella, the top prize in the 13-14 age category. The eight-grader says he stumbled upon the idea in the summer of 2013, following an unsuccessful attempt to squash fruit flies that were feasting on some ripe bananas. This led the youngster to wonder if small robots built with similarly quick instincts could be used to map the damage caused during earthquakes. While small-helicopter-like robots called quadrotors built for this purpose already exist, they are not capable of sensing and avoiding falling debris, which limits their usefulness in disaster zones.

So the young boy decided to create the Flybot. He began by fitting a small commercial quadrotor with two simple infrared distance sensors and then used his programming skills to ensure that the tiny device could sense and move away from moving objects as efficiently as the pesky fruit flies. Mihir was awarded $25,000 USD and a full-year's mentorship from an expert, to pursue his project further.

Cleaning Up Oil Sands Waste

Haley Todesco, a 17-year-old from Alberta, Canada, took home the title in the 17-18 age group category. For her project, she tackled another big world issue - pollution caused by oil extraction. According to the young girl when a heavy oil known as bitumen is extracted from oil sands (a natural mixture of sand, water, clay and oil), the residue left behind contains toxic non bio-degradable compounds that are collectively known as Naphthenic acids (NAs). These could present a major environmental hazard for humans and wildlife if allowed to accumulate.

Her invention, which was inspired by a fifth grade project that involved using pop bottles and sand to make water filters, involves cleaning up the toxic waste in a quick and efficient manner using filters made from sand and bacteria. It took the young girl two years of research and countless number of experiments, to make this breakthrough.

But it has been worth it. In addition to the Google category win, on September 3rd, she also received the 2014 Stockholm Junior Water Prize, which came with a scholarship of $15,000 USD and an additional $5,000, for her school.

Also recognized for their brilliant inventions were two other teenagers. 15-year-old New Yorker Kenneth Shinozuka won the Scientific American Science in Action award, for building a wearable sensor that helps people suffering from Alzheimer's disease. India's Arsh Dilbagi, took home the Voters Choice award for his device that enables people with speech impediments, to communicate by exhaling.

To read about some of the other cool inventions or find out how you can help change the world, check out: