The carbon footprint argument it a little weak. The impact of producing fertiliser has already be spent and its just sitting there stockpiled waiting for a market. They never mention that none of the fertiliser used in algae farming will ever contaminate the land or waterways. Some twit even worked up a carbon footprint on pet ownership, dogs being the worst because they eat red meat. I'm waiting for the study on how eco-unfriendly having children is.