Once in the assessment center, there is a group task first followed by individual interviews. The group project doesn't require a lot of previous knowledge but it'll be useful to understand the energy market. Mainly just looking for people who are charasamtic and contribute, For the individual interviews, a knowledge of CCGTs is required, There are also technical questions specific to each role but most likely there will be a question you won't be able to answer. The main thing is to not make up anything, just be honest when you don't know and they might give you a clue. They're looking to see you're thought process.