To date, studies of energy siting controversy and of environmental psychology have barely informed one another, despite the environmental-behaviour literature potentially having considerable relevance to understanding public opposition to energy projects. This paper points towards this relevance, using the example of a longitudinal study of public objections to a 21.5 MWe bioenergy gasifier proposed for Winkleigh in Devon, England. Local opinion surveys in 2004 and 2007 showed that public opposition to the proposed gasifier remained strong but also revealed some statistically significant change and correlations of wider interest. In the context of the environmental psychology literature, the dominant model of contextualised values, intention and behaviour, as well as other psychological approaches, are found to be helpful, both for making sense of the results and for informing a psychological research agenda on public objection to new energy infrastructure.