In Energy at the Crossroads, Vaclav Smil considers the twenty-first century's crucial question: how to reconcile the modern world's unceasing demand for energy with the absolute necessity to preserve the integrity of the biosphere. With this book he offers a comprehensive, accessible guide to today's complex energy issues -- how to think clearly and logically about what is possible and what is desirable in our energy future. After a century of unprecedented production growth, technical innovation, and expanded consumption, the world faces a number of critical energy challenges arising from unequal resource distribution, changing demand patterns, and environmental limitations. The fundamental message of Energy at the Crossroads is that our dependence on fossil fuels must be reduced not because of any imminent resource shortages but because the widespread burning of oil, coal, and natural gas damages the biosphere and presents increasing economic and security problems as the world relies on more expensive supplies and Middle Eastern crude oil. Smil begins with an overview of the twentieth century's long-term trends and achievements in energy production. He then discusses energy prices, the real cost of energy, and "energy linkages" -- the effect energy issues have on the economy, on quality of life, on the environment, and in wartime. He discusses the pitfalls of forecasting, giving many examples of failed predictions and showing that unexpected events can disprove complex models. And he examines the pros and cons not only of fossil fuels but also of alternative fuels such as hydroenergy, biomass energy, wind power, and solar power. Finally, he considers the future, focusing on what really matters, what works, what is realistic, and which outcomes are most desirable.