Promotion costs a lot can be more expensive than the development of the project itself, because now without advertising is not one project and does not live long on the market
In the case of project Greencoin, promotion can be much cheaper and easier because the project plans to work in the field of environmental protection and many people are willing to donate development assistance to the project.
By the way, there are some environmental and charity organisation and Greencoin can have a promotion with their help.