This book is a reality check of where energy will come from in the future. Today, our economy is utterly dependent on fossil fuels. They are essential to transportation, manufacturing, farming, electricity, and to make fertilizers, cement, steel, roads, cars, and half a million other products. One day, sooner or later, fossil fuels will no longer be abundant and affordable. Inevitably, one day, global oil production will decline. That time may be nearer than we realize. Some experts predict oil shortages as soon as 2022 to 2030. What then are our options for replacing the fossil fuels that turn the great wheel of civilization? Surveying the arsenal of alternatives – wind, solar, hydrogen, geothermal, nuclear, batteries, catenary systems, fusion, methane hydrates, power2gas, wave, tidal power and biomass – this book examines whether they can replace or supplement fossil fuels. The book also looks at substitute energy sources from the standpoint of the energy users.  Manufacturing, which uses half of fossil fuels, often requires very high heat, which in many cases electricity can't provide. Industry uses fossil fuels as a feedstock for countless products, and must find substitutes. And, as detailed in the author's previous book, "When Trucks Stop Running: Energy and the Future of Transportation," ships, locomotives, and heavy-duty trucks are fueled by diesel. What can replace diesel? Taking off the rose-colored glasses, author Alice Friedemann analyzes our options. What alternatives should we deploy right now? Which technologies merit further research and development? Which are mere wishful thinking that, upon careful scrutiny, dematerialize before our eyes? Fossil fuels have allowed billions of us to live like kings. Fueled by oil, coal, and natural gas, we changed the equation constraining the carrying capacity of our planet. As fossil fuels peak and then decline, will we fall back to Earth? Are there viable alternatives?