I have attached a random greenhouse as an illustration for my idea of vertical Algae farming. By using vertical tubes in a greenhouse, you can grow algae to extract oil from, which is already replacing Palm Oil. Most of the loss of Orangutan habitat is due to Palm Oil plantations. These greenhouses keep the selected algae species from being contaminated by wild algae spores as this oil is to be used for food production. It also enables the use of Carbon Dioxide gas to speed up the growth of the algae. The greenhouse design is usable anywhere there is a minimum of space available, such as on barges, building roofs, warehouses or even below ground with LED lighting.
As the water is merely a support medium, fresh, brackish or even salt water can be used. The water is removed in the extraction process and recycled.