The car tires were abundant and easy to spot. As were newspapers, made from trees with tough cell walls. Then there were tons of soil aged and packed with decomposed garbage from the 1980s, when Madonna belted out “We are living in a material world, and I am a material girl” and Star Wars brought us a future that didn’t seem to include trash cans anywhere.

At the closed Perdido Landfill in Escambia County, Florida, they’re digging into the past to eliminate old garbage that could contaminate groundwater and clear space for future trash. In the process, they’re also mining for any treasure that could help offset the cost of doing so. During its first phase, which ran from 2009 to 2011, the dig uncovered a copious amount of soil that was then used to cover up new trash, a practice required by federal and state regulations.

This article was originally published by Ensia.

Can autonomous cars be a boon for the environment?

The transportation sector is the second largest source of greenhouse gas emissions in the United States, accounting for 27 per cent of the harmful gases emitted into the atmosphere, according to the U.S. Environmental Protection Agency. On the road, cars in the U.S. guzzle about 2 billion barrels of oil each year.

The rooftops of school buildings are rarely considered hot real estate. But tiling them with solar panels has proven an effective way for Potentia Solar to grow its project development and management business.

The Toronto-based company, founded in 2000, has built 45 megawatts of projects at over 200 school sites across Ontario. It's working on installing another 45 megawatts at hundreds more, says Potentia chief executive Daniel Argiros.