Sophisticated attacks on Energy Delivery Systems (EDS) are no longer theoretical, and instead pose a serious threat to American economies. The EDS community has worked collaboratively to develop security requirements to protect EDS against such attacks, but the documents that contain these requirements are often dense, ambiguous and difficult for humans to understand, resulting in highly subjective security implementa-tions that reduce their effectiveness. Therefore, there is a need for a methodology that models and visualizes security requirements enabling quick retrieval, understanding and analysis, along with the evaluation and evolution of the implementations of such requirements within EDS. With this in mind, this paper presents a collaborative tool called OntoEDS that provides a well-defined representation of security requirements within ontological representations, and a set of ontology exploration techniques to analyze and evaluate the implementations of such requirements against the current attack surface. We also present a case study exemplifying the usefulness of our tool surrounding the series of EDS attacks that occurred in Ukraine in 2015 and 2016.