Renewable energy Great hope or false promise

During the course of 1991 a series of viewpoint papers will be published in Energy Policy on the subject of renewable energy. In this article, the guest editor for the series discusses the motivation for addressing this issue at the present time, and lays down a challenge, based on consideration of the thermodynamic impacts of post-industrial energy-use, which presents itself first and foremost to proponents of renewable energy: do renewable energy technologies offer the hope of providing clean, long-term energy options for the 21st century, or do they present only false promises which have no significant hope of realization in the foreseeable future?