Isabella O'Brien, 13, of Dundas, Ont., and Calvin Rieder, 18, of Oakville, Ont., were two of 20 finalists who will travel to Google headquarters in Mountain View, Calif., to present their projects to the competition's judges in person. The winners will be announced on Sept. 21.
O'Brien, who will start Grade 9 in September, wanted to find a way to reduce ocean acidification caused by increased carbon dioxide in the atmosphere from burning fossil fuels.
Two years ago, while on a trip to Mexico with her family, she went diving and saw a lot of dead coral. At a nearby ecological centre, she read about ocean acidification and how it was damaging the coral.
After some more research, she learned that adding calcium carbonate to the oceans could be a possible solution. She also determined that the seafood industry generates six million tonnes of shells a year from oysters, clams and mussels. Those shells are made of calcium carbonate.
"Right now, they generally go to the landfill," she said.
O'Brien thought she might be able to find a better use for them. For her Grade 7 science project at St. Augustine Catholic Elementary School in Dundas, Ont., she tested how ground-up shells added to jars of seawater would affect the acidity, and found they did make the water less acidic. The project made it all the way to Canada's national science fair.
"Even though buffering the entire ocean isn't feasible, it might be possible to create protected marine areas to mitigate local impacts of ocean acidification and ensure the survival of our most threatened marine organisms," she said in a video submitted to the Google Science Fair.
Rieder's project involved building two systems to provide cleaner drinking water for people in the developing world.
He had read that there were a billion people around the world who don't have basic access to water, and some walk many hours each day to collect the water they need to survive.
"I found this really shocking," said Rieder, who just graduated from Grade 12 and will be starting an engineering program at the University of Toronto this fall. "I wanted to do something."
While camping, he learned about a trick for collecting water vapour from the air.
"You can dig a hole and stretch a piece of plastic over it, and at night water can condense on the plastic, which can be collected."
He decided to see if the same concept could be used on a bigger scale to help people without good access to water.
He started working on the project in Grade 7. Initially, his system would only collect water if the air was very humid — if it came from a clothes dryer exhaust, for example. He made little improvements every year, and within three years, he could collect water from normal air.
The latest version, an aluminum condenser with reflectors and a radiator panel to help cool it, has collected nearly a litre in one night.
He has also incorporated the condenser into a water purification system called a solar still for use in places that have contaminated water.
O'Brien, Rieder, and the other finalists have the chance to win prizes that include a $50,000 scholarship, a 10-day National Geographic Expedition to the Galapagos, a trip to the LEGO headquarters in Billund, Denmark, and a tour of Virgin Galactic's Mojave Air and Spaceport.