A friend recently pointed me in the direction of the Sustainable Energy Authority of Ireland website. They have a tonne of fantastic resources - books, worksheets, posters and lesson plans available - for free. They cover terms such as renewable energy, recycling, acid rain, etc. You can download a lot of these as PDFs here. There are some fantastic ideas for geography and science (and the ethical curriculum if you're in an Educate Together school) lessons including experiment sheets. This is definitely one to check out!