Modern (that is, overwhelmingly fossil-fueled) civilization needs highly concentrated sources of energy that can be conveniently delivered to the megacities where most of humanity will soon live. No other fuel can fit this need as efficiently and with such a relatively low environmental impact as natural gas (its combustion releases less carbon dioxide per unit of useful energy than coal or oil). The conclusion is obvious: The world should speed up its unfolding transition from coal and crude oil to natural gas by using the fuel not only for heating, electricity generation, and as feedstock for industrial syntheses but also as a transportation fuel. Spending toward that goal would bring faster and more durable gains than subsidizing such dubious conversions as turning corn into ethanol or pouring huge sums into money-losing solar enterprises.


–Vaclav Smil, Professor of Environment at the University of Manitoba, Placing the American Gas Boom in Perspective