He estimates that, with one barrel of oil comprising 42 gallons, each tonne of oil shale contains approximately 25 gallons.
Times, Sunday Times (2011)
The sustained rise in energy prices has led some to forecast that a barrel of oil could be trading for more than $70 within the next year.
Times, Sunday Times (2017)
The cost of a barrel of oil depends on how and where it is produced.
Times, Sunday Times (2008)