http://spectrum.ieee.org/energy/renewables/a-skeptic-looks-at-alternative-energy/0

Skeptic is too strong a word. Realist?

“Perhaps the most misunderstood aspect of energy transitions is their speed. Substituting one form of energy for another takes a long time. U.S. nuclear generation began to deliver 10 percent of all electricity after 23 years of operation, and it took 38 years to reach a 20 percent share, which occurred in 1995. It has stayed around that mark ever since. Electricity generation by natural gas turbines took 45 years to reach 20 percent.

“In 2025 modern wind turbines will have been around for some 30 years, and if by then they supply just 15 percent of the electricity in the United States, it will be a stunning success. And even the most optimistic projects for solar generation don’t promise half that much. The quest for non­carbon sources of electricity is highly desirable, and eventually such sources will predominate. But this can happen only if planners have realistic expectations. The comparison to a giant oil tanker, uncomfortable as it is, fits perfectly: Turning it around takes lots of time.

“And turning around the world’s fossil-fuel-based energy system is a truly gargantuan task. That system now has an annual throughput of more than 7 billion metric tons of hard coal and lignite, about 4 billion metric tons of crude oil, and more than 3 trillion cubic meters of natural gas. This adds up to 14 trillion watts of power. And its infrastructure—coal mines, oil and gas fields, refineries, pipelines, trains, trucks, tankers, filling stations, power plants, transformers, transmission and distribution lines, and hundreds of millions of gasoline, kerosene, diesel, and fuel oil engines—constitutes the costliest and most extensive set of installations, networks, and machines that the world has ever built, one that has taken generations and tens of trillions of dollars to put in place.

“It is impossible to displace this supersystem in a decade or two—or five, for that matter. Replacing it with an equally extensive and reliable alternative based on renewable energy flows is a task that will require decades of expensive commitment. It is the work of generations of engineers.”