YOUR NEXT CAR WILL BE A VOLT:

The convulsions in the clean-tech sector are simply symptoms of a cycle that characterizes emerging technologies: excitement, inflated expectations, and consolidation - ultimately followed by stability and the resumption of growth. Indeed, underlying recent developments are signs of a much more significant transformation: clean tech is becoming commercially viable.

Confidence in the clean-tech sector's future is rooted in the need for sustainable solutions for a planet that is supporting an ever-wealthier population. Over the next 20 years, the number of middle-class consumers is expected to rise to some three billion, from 1.8 billion today. Their new lifestyles will require resources, including energy.

This surge in demand will occur at a time when finding, developing, and extracting new sources of energy and resources will be increasingly challenging and expensive. Over the last 12 years, for example, the average real construction cost of an oil well has doubled, and in recent years new mining discoveries have been few, despite the industry's best (and often expensive) efforts. But clean-energy costs are trending in the opposite direction, ripening these solutions at a time when need - particularly in some of the world's largest developing cities - is becoming acute.

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