This book serves as a starting point for energy engineers, sustainability managers, political leaders, and properly informed citizens to explore the net value added by energy systems. Since some resources deplete and some new technologies will require time to emerge, the book takes the reader through the range of costs and benefits, considering the contexts of geography, human needs, and of time. The book takes a particularly close look at the underdeveloped world that currently lacks access to modern energy, and which is crippled by its dependence on dirty, inefficient biomass fuels to meet bare subsistence needs. The authors provide evidence for the reality that energy provides tremendous social value, ranging from the most basic survival to development, to great luxury, inevitably, at a cost. Based on this evidence the reader will be well-equipped to ask the questions: Which energy resources should be abandoned and which should be embraced as we strive for a sustainable future?