Actual trains are very fuel efficient for what they do. They emit less bad exhaust per ton than any gas/diesel powered car or SUV. And far greener than airplanes. Trains have been diesel-electric hybrids for decades now, long before cars learned that trick. That big diesel motor generates electricity for the traction motors underneath. At switch yards, they have smaller engines are totally electric. Here, the weight of the batteries is a positive feature, giving the train more ability to push/pull heavy loads.