This new methodology will be applicable to project activities that collect Sargassum or other waste macroalgae species that would otherwise be disposed in a landfill, and processes this macroalgae into useful products. As a result, less waste is put into landfills and fewer methane emissions will take place from the baseline scenario. In addition, the products made from the waste macroalgae may also displace more carbon-intensive products, further reducing GHG emissions. The methodology is intended to apply globally and can use any kind of macroalgae species that meets the definition of waste macroalgae. The macroalgae should be collected on-shore or near-shore and not collected in the open ocean.