Global nuclear power capacity grew by less than 2,000 megawatts in 2007, a figure equivalent to just one-tenth of the new wind power installed globally last year, according to the latest Vital Signs Update from the Worldwatch Institute. Global nuclear capacity stands at 372,000 megawatts, but ranks as the slowest growing energy source—just 0.5 percent in 2007, compared to wind at 27 percent.

By the end of 2007, some 34 nuclear reactors were being built worldwide, 12 of which had been under construction for 20 years or more. Asia accounts for the most nuclear power plant construction, with 20 new reactors currently under way. India and China each have six reactors under construction, accounting for 8,130 megawatts, or more than a quarter of the nuclear capacity currently being built worldwide. More than 124 reactors have been retired by the commercial nuclear industry since 1964, amounting to a total of 36,800 megawatts of generating capacity.

Construction delays and cost overruns continue to plague the nuclear industry. Cost estimates for identical Westinghouse-designed nuclear plants more than doubled in 2007, to $12–18 billion, raising questions about the plants’ economic viability and doubts as to how many electric utilities would be willing to add liabilities of that scale to their balance sheets. This on top of the massive amounts of radioactive waste, and potential security (read dirty bomb/nuclear weapons) problems that these reactors cause.

In Japan, a 6.8-magnitude earthquake struck the largest nuclear complex in the world in 2007, shutting down the Kashiwazaki-Kariwa nuclear plant’s seven reactors, which account for 8,000 megawatts of Japan’s nuclear capacity. The quake was two and a half times more powerful than the reactors were designed to withstand, raising questions about whether they should ever be returned to service.

The United States saw no nuclear construction starts for the 29th straight year in 2007, though one reactor was restarted after a 22-year shutdown, and construction resumed on another reactor that had been stalled since 1988. While electric utilities submitted applications for seven new reactors, and government regulators expect additional applications in 2008, industry officials are seeking additional federal loan guarantees as a prerequisite to starting plant construction. The U.S. credit rating agency Moody’s has cautioned that many utilities are underestimating the cost of new plants and that nuclear investment could damage their credit ratings.