For most of human history, the dominant concerns about energy have centered on the benefit side. Inadequacy of energy resources of the technologies for harvesting, converting, and distributing those resources has meant insufficient energy benefits to human beings and hence inconvenience, and constraints on its growth. The 1970’s, then, represented an turning point. Energy was seen to be getting costlier in all respects. It began to be believable that excessive energy costs could pose threats on a par with those of insufficient supply. It also became possible to think that expanding some forms of energy supply could create costs exceeding the benefits.