Your goal isn't writing a book. It is solving a problem or educating the masses about a topic or entertaining people in need of cultural release. Identify what you are doing, then put your plan to paper. Put your thoughts on paper and state your goals. Then seek those grants.
Grants arise from foundations, endowments, nonprofits, and charities.
But they also come from businesses and corporations. The key is to find the sponsor that matches your needs then preparing a request that makes them come looking for you waving a check. Your writing skills must be used in your solicitation as much or more than in your actual project. As a writer, you have a project, or else you have a hobby. It is that simple.