By Marc Gunther, senior writer at FORTUNE magazine, a columnist at CNNMoney.com, and the author of Faith and Fortune: How Compassionate Capitalism is Transforming American Business

Technology got us into this mess—a planet that’s heating up, with potentially catastrophic consequences. Our cars, our homes, our office buildings, our appliances, our computers, MP3 players and big-screen TVs all require burning fossil fuels and emitting greenhouse gases into the atmosphere. That’s the bad news. The good news is that technology can get us out of this mess—although not by itself.

As the environment writer for FORTUNE magazine, I’ve always enjoyed visiting Silicon Valley. It’s brimming with ambition and ideas and optimism and the can-do spirit that, not to be too corny about it, helped to make America what it is today. Places like Silicon Valley, where inventors, entrepreneurs and investors come together, will enable us to made an exciting and dramatic transition to a new clean energy economy.

How? If I could answer that question, I might quit my job, work on the solution and get rich. The fact is, there will be many new products and services that will take us closer to a sustainable, clean energy economy. Last year, Venture capitalists in the U.S. invested $2.7 billion in the clean-energy sector, representing about 9 percent of venture investing, according to Clean Edge, a research firm.

Here are just a few examples of technology-driven pathways to sustainability:

Energy efficiency. This is a huge opportunity, and one that won’t cost a lot of money. A McKinsey study found that about 40 percent of the greenhouse gas emissions reductions required by climate-change legislation pending in Congress could be achieved in ways that save money, by saving energy.

You’re probably reading this on a computer. Was it certified as an Energy Star machine by EPA? Microsoft, Intel, HP, Dell and many others are now working hard to get computers to run efficiently. IBM, Google, and Microsoft have found that they can save lots of energy and reduce emissions by running vast data centers more efficiently.

Renewables. The solar and wind energy businesses, while small, are booming, thanks to improved design of solar photovoltaic panels, solar thermal power plants and wind turbines. I was surprised to learn recently that about 25% of the new power-generating capacity built in the U.S. in 2007 was wind power—for the most part, replacing coal plants. Venture capital firms have financed dozens of solar startups that think they can bring down the costs of making electricity from the sun. Check out Ausra, eSolar and Makani Power, to name just three.

Alternative fuels: Putting ethanol from corn into our cars was not a good idea, but next-generation biofuels promise to get us where we want to go more cleanly, with the added benefits of reducing dependence on imported oil. Big companies like BP and Chevron are investing in biofuels, as are startups like Amyris Biotechnologies. The scientists there have already figured out how to engineer microbes to make a low-cost malaria drug. Now they are working on a fermentation process to create low-cost, clean substitutes to gasoline and diesel.

Electric cars: You’ve probably heard of the Chevy Volt, a plug-in electric car General Motors wants to get to market by 2010. The key here is creating batteries at an affordable price to store the electricity we need to drive long distances. But did you know that a U.S. startup called Project Better Place is working with Nissan and the state of Israel to get all of that nation’s cars running on electricity instead of oil?

I could go on. Clean technology will get us a smarter and more efficient electricity grid. It will get us intelligent green buildings. It will help companies manage their cars and trucks more efficiently, help cities ease traffic congestion and help each of us measure and reduce our personal carbon footprints.

Of course, technology can’t do this alone. We need the right government policies—above all, one that puts a price on carbon emissions, and thereby unleashes the power of capital and innovation to develop all these clean energy consumers. And we need to take responsibility, as citizens and especially as consumers for the impact of our own behavior. We need to buy less, waste less and conserve more—if not for ourselves, for the sake of generations to come.

About the Author

Marc Gunther has written for FORTUNE magazine since 1996. www.marcgunther.com