Contrary to the hopes and wishes of green entrepreneurs, investors, and zealots everywhere, fossil fuels will dominate the global economy for at least the next twenty years. Beyond that point, breakthroughs in nuclear fission and fusion—or even wind, water, and solar, may become cost-effective, safe, and reliable enough to replace fossil fuels. Why is this true? What are the implications? What will it mean for each of us? We’ll explain.