Should I publish the idea on my blog? Try to contact a company who would be interested? Try to patent the idea? Thanks for any advice.
then, you can start openly discussing the invention either with investors or companies while you work through the full patent process.
If the invention is not patentable, then I'd say write about it, contact companies or people who might be interested.
If you want to be involved in the project long-term, make sure they are aware of that, and maybe they'll hire you on if you've got the requisite skill.
As a green initiative which 'might' be profitable, don't ignore grants or philanthropic groups which may be interested in funding or introducing you to people who might be able to help.
In general, find a way to protect your idea, and then get out there and talk about it.
There will still be a target market for certain Green things no matter who is in control though, because there is an identifiable subset of consumers who value it enough to pay for it.