Clean energy can put America back to work.

Clean energy, the power behind a low-carbon economy, is no fad.

Angela Merkel, chancellor of Germany, has called it the "third industrial revolution," following coal and oil. Cisco has said it's bigger than the Internet. It involves all sectors - engineering, technology, steel, manufacturing, software and of course, the noble trades. But only those countries with solid, far-thinking policy commitments to support the growth of that industry will get a piece of this enormous economic pie. America is missing the boat, and ignores at its peril lessons from its own history.

Almost all of the high-tech sectors that drove the American manufacturing machinery during the 20th century were the result of policy decisions by the federal government. While those who adhere to free-market ideology may be loathe to admit it, the big economic drivers - from the auto sector to aerospace, from the Internet to medicine - were all seeded by smart policy and the public sector. These markets were shaped and supported during their initial stages. Clean energy is no different.

Silicon Valley, an ongoing source of technological prowess and economic might, was born not only by entrepreneurs toiling away in their garages. Military and economic demand for the microchip is what enabled the industry to lower costs enough to address the consumer market. The Internet itself came about largely because of development and demand on the academic side. Aerospace dominance also came about through military demand. Medical advances have always been supported by the public sector, predominantly through the National Institutes of Health. Even the auto sector got its big boost through the federal government's decision to build the interstate highway system.

It is now inevitable that the world will transition to a low-carbon economy. Americans may dither on climate change, but the atmosphere cares nothing for political or ideological argument. There is no significant doubt in the scientific community about what's happening to the climate. Indeed we've known since the mid 1800s that carbon dioxide is a greenhouse gas. Lowering carbon emissions is not optional.

But climate change is only part of the picture. The need for energy security and cleaner air also drives this sector.

The upside is this: The transition to a low-carbon economy will be the largest infrastructure build in human history. Trillions of dollars will be deployed globally over the next several decades. Countries will be net buyers or net sellers of this technology. If America gets it right, we will be selling this stuff to the rest of the world, and our manufacturing sector will run at capacity to meet the upsurge in demand for clean technology.

Solar power will come from next-generation solar panels and giant solar thermal plants that focus the sun's rays to generate steam. These plants will produce power well after dark by storing some of that heat in a giant thermos. A network of giant wind turbines, both onshore and offshore, will be connected together with high-efficiency DC lines. This is how wind energy becomes reliable. Enhanced geothermal wells will mine the heat that exists beneath our feet.

Building retrofits will lower our energy use, and make our economy more profitable, as will more efficient industrial processes. Third-generation biofuels that do not compete with food will provide liquid fuels, and large-scale battery production will power electric cars.

This transition will employ people across all sectors and so means more to American workers than the Internet ever did. But right now, China is creating those jobs. Europe is building that technology.

Clean energy can put Americans back to work. But we need clear, strong signals from the federal government that this sector is of strategic importance. We've done it before, and were rewarded with decades of economic growth.

Tom Rand, PE, Ph.D., is a venture capitalist, author and engineer. His latest book is "Kick the Fossil Fuel Habit." To reach him, visit www.tomrand.net.