Globe and Mail: Conventional fossil fuels will keep their status as the main source of global energy for at least the next two decades, but some renewables — such as biofuels, solar power and onshore wind — should soon be able to compete effectively without subsidies, according to a new study. International business advisory firm Boston Consulting Group released a report Wednesday that examined seven key renewable energy sectors. It projects dramatic gains for some in the short term, while others are expected…