E3 - Despite fears of "peak oil", Professor Iain Stewart discovers that huge technological advances are helping extend the life of existing oilfields, and new unconventional oil and gas supplies like shale gas and tar sands are extending the hydrocarbon age well into the 21st century.

E5 - The vast, quiet plains of the Canadian prairies are home to some of the most productive ecosystems in North America thanks to a seemingly insignificant organsim - grass!