For a century, almost all light-duty vehicles (LDVs) have been powered by internal combustion engines operating on petroleum fuels. Energy security concerns about petroleum imports and the effect of greenhouse gas (GHG) emissions on global climate are driving interest in alternatives. Transitions to Alternative Vehicles and Fuels assesses the potential for reducing petroleum consumption and GHG emissions by 80 percent across the U.S. LDV fleet by 2050, relative to 2005. This report examines the current capability and estimated future performance and costs for each vehicle type and non-petroleum-based fuel technology as options that could significantly contribute to these goals. By analyzing scenarios that combine various fuel and vehicle pathways, the report also identifies barriers to implementation of these technologies and suggests policies to achieve the desired reductions. Several scenarios are promising, but strong, and effective policies such as research and development, subsidies, energy taxes, or regulations will be necessary to overcome barriers, such as cost and consumer choice.

Lately it has become a matter of conventional wisdom that hydrogen will solve many of our energy and environmental problems. Nearly everyone -- environmentalists, mainstream media commentators, industry analysts, General Motors, and even President Bush -- seems to expect emission-free hydrogen fuel cells to ride to the rescue in a matter of years, or at most a decade or two. Not so fast, says Joseph Romm. In The Hype about Hydrogen, he explains why hydrogen isn't the quick technological fix it's cracked up to be, and why cheering for fuel cells to sweep the market is not a viable strategy for combating climate change. Buildings and factories powered by fuel cells may indeed become common after 2010, Joseph Romm argues, but when it comes to transportation, the biggest source of greenhouse-gas emissions, hydrogen is unlikely to have a significant impact before 2050. The Hype about Hydrogen offers a hype-free explanation of hydrogen and fuel cell technologies, takes a hard look at the practical difficulties of transitioning to a hydrogen economy, and reveals why, given increasingly strong evidence of the gravity of climate change, neither government policy nor business investment should be based on the belief that hydrogen cars will have meaningful commercial success in the near or medium term. Romm, who helped run the federal government's program on hydrogen and fuel cells during the Clinton administration, provides a provocative primer on the politics, business, and technology of hydrogen and climate protection.