2008 Winner: Outstanding Achievement In Environmental Technology And Innovation
Managing Garbage To Solve Big Problems
Dr. Patrick Hettiaratchi has a mission to change the way people think about garbage. He’s designed a revolutionary landfill ‘biocell’, which will contribute to solving some of the major problems the world is facing.
“Our biocell can help control climate change by reducing methane emissions,” he explains. “It can reduce energy consumption by creating energy from the garbage, which will also affect oil and gas prices; and it addresses land use because most of the garbage will be converted to usable compost and we can reuse the landfill site and reduce traditional landfill use.” The biocell is a large pit lined with clay and plastic. It is loaded with tonnes of ordinary garbage. When it is filled, the biocell is sealed with an organic bio-cap that lets in water but traps gases. Oxygen is sucked out of the biocell and water is added. Using a pump, the leachate is continually circulated to accelerate breakdown of the waste and increase methane output. The gas is captured and used to make electricity, theoretically about 300 kilowatts of power for about three years. When the methane production dwindles, oxygen is pumped back into the biocell and it becomes a giant composter, a process that takes about a year. The biocell is opened, compost is removed, recyclable material is harvested and the rest, about 30 per cent of the original volume, is moved to a traditional landfill. Then another biocell is set up on the same location.
Before Dr. Hettiaratchi’s biocell can accomplish the ambitious agenda, municipalities have to buy into the concept – starting with Calgary.
Dr. Hettiaratchi and the City of Calgary are conducting a full-scale pilot project of the biocell. It covers one hectare and has the capacity to process 55,000 tonnes of waste over the next five years, theoretically at least. “What works in Calgary may not work in Indonesia,” he observes. “But every country has a problem with garbage and the idea of the biocell is worth pursuing.” He cites the amount of moisture and the type of garbage as variables that need to be considered when designing the biocell.
Dr. Hettiaratchi is building an international biocell network to help advance the technology for use in various climates and conditions.
“What to do with all of our garbage is one of the world’s biggest problems,” he says. “We hope our project in Calgary gets good results so we can provide information to policy makers to make the decision to use the biocell. It has the potential to solve some of the world’s problems and benefit all of society in several ways.”
