Certainly we will need many different technologies to stop global warming. They include electric cars and plug-in hybrids, wind turbines and solar photovoltaics, which use sunlight to make electricity from solid-state materials like silicon semiconductors. Yet after speaking with energy experts and seeing countless presentations on all forms of clean power, I believe the one technology closest to being a silver bullet for global warming is the other solar power: solar thermal electric, which concentrates the sun's rays to heat a fluid that drives an electric generator. It is the best source of clean energy to replace coal and sustain economic development. I bet that it will deliver more power every year this century than coal with carbon capture and storage -- for much less money and with far less environmental damage.

Clearly, the world needs a massive amount of carbon-free electricity by 2050 to stabilize greenhouse gas emissions. The industrialized countries need to cut their carbon dioxide emissions from electricity generation by more than 80 percent in four decades. Developing countries need to find a way to raise living standards without increasing electricity emissions in the short term, and then reduce those emissions sharply. And, over the next few decades, the world needs to switch to a ground transportation system whose primary fuel is clean electricity.

This electricity must meet a number of important criteria. It must be affordable: New electricity generation should cost at most about 10 cents per kilowatt hour, a price that would probably beat nuclear power and would certainly beat coal with carbon capture and storage, if the latter even proves practical on a large scale. The electricity cannot be intermittent and hard to store, as is energy from wind power and solar photovoltaics. We need power that either stays constant day and night or, even better, matches electricity demand, which typically rises in the morning, peaks in the late afternoon, and lasts late into the evening.

This carbon-free electricity must provide thousands of gigawatts of power and make use of a low-cost fuel that has huge reserves accessible to both industrialized and developing countries. It should not make use of much freshwater or arable land, which are likely to be scarce in a climate-changed world with 3 billion more people.

Solar electric thermal, also known as concentrated solar power (CSP), meets all these criteria. A technology that has the beauty of simplicity, it has proved effective for generations. As the Web site of CSP company Ausra illustrates, solar thermal has a long and fascinating history.

Back around 700 B.C., the Chinese first used "burning mirrors" to ignite firewood. In 230 B.C., a colleague of Archimedes built a parabolic mirror, which focuses the sun's rays to a single point, also better for starting fires. Around 212 B.C., Archimedes supposedly had Greek soldiers use their bronze shields to concentrate the sunlight on Roman ships and set them on fire.

In the 15th century, the Italians used burning mirrors to solder copper sections of the Santa Maria del Fiore cathedral. Leonardo da Vinci's notebooks contain many designs for solar concentrators, including some for industrial purposes, because he worried about the destruction of the earth's vast forests in humanity's search for fuel.

In the 1860s and 1870s, Augustin Mouchot built the first dish-shaped reflector that ran a heat engine, and he used solar thermal to heat a boiler that ran an ice maker. His assistant demonstrated a printing press running on concentrated solar. But all this work came to naught because of the general lack of direct sunlight in France and the abundance of cheap coal, which became a primary energy source for the Industrial Revolution.

A Swedish immigrant to America, John Ericsson, developed a motor driven by parabolic trough mirrors in 1870. In 1909, H.E. Wilsie added a critical component, a system for storing solar energy for when the sun did not shine. Heat is much easier to store than electricity, a fact that gives CSP a crucial -- maybe the crucial -- advantage over wind and solar photovoltaics.