These grants are usually advertised at the beginning of summer with the deadlines at the end of summer. It used to be known as Local Agenda 21 Environmental Partnership Fund or LA21 until recently and it still helps to search for it that way. It helps to support local environmental initiatives.
Here is a link to Fingal County Council‘s website; they have put up a pdf with the national list of successful 2019 projects with short descriptions and their various local authorities. Dun Laoghaire-Rathdown County Council and Dublin City Council have a page on their website for it as well, and South Dublin County Council has one for 2018.
Here is a link to the Irish government’s page about Local Agenda 21, with a very good list of contacts and information. Additionally, it might be an idea to search over a past list for projects similar to yours for ideas. For example, if your project was to do with bees, you could go to the national list of 2019 projects and press ‘Command + f’ (keyboard command for ‘find’) and type ‘bees’ into the search box to look for projects where the word ‘bees’ appears.