The Bioil RigTM: growing carbon neutral fuels to replace all fossil oil extraction

Greenlight Bio Oil LLC’s patent-pending process grows and harvests locally sourced marine microalgae and cyanobacteria offshore, processes them into biofuel and converts the remaining matter into fertilizer to grow more microalgae. The process absorbs as much CO2 in fuel production as is created when the fuel is used: true carbon neutrality. 

Current research into growing algae is concentrated in developing land-based systems: either photobioreactors where algae are grown indoors in closed systems often under artificial light, or in purpose-built ponds. These have several disadvantages for the mass industrialization needed to have a significant impact on climate change. Although the productivity of algae farming is much greater than arable farming, tens of millions of acres of land and billions of tons of water would be required to generate sufficient energy to replace fossil fuels at their current rate of use. Rather than the difficult and expensive process of replicating the marine environment on land, Greenlight Bio Oil LLC proposes growing marine algae in their natural environment using an installation we call a Bioil Rig^TM. 

The Bioil Rig^TM is composed of an interconnected array of modular enclosures that float below the ocean surface. Some of these enclosures have impermeable walls. These are stocked with local algae and bacteria and kept in a nutrient-rich environment to promote rapid growth. Once sufficent biomass concentration is reached, the algae are transferred to other enclosures that have permeable walls to allow seawater to pass through. As the local sea water is rich in dissolved inorganic carbon (DIC), but poor in micronutrients, autotrophic growth becomes focused on producing lipids and carbohydrates with little reproduction. The algae are harvested when their rate of biomass growth tapers off and transferred to a processing platform. 

The algae are processed to separate out their lipids, in a similar process to vegetable oil production. Other useful products may be separated, and the remaining bioavailable material is returned to the impermeable enclosures to promote further growth. System losses of nitrogen-containing chemicals should be replaced by growing nitrogen-fixing bacteria. But other micronutrients such as phosphorous may have to be imported. So, limiting system losses is essential to economic production. However, as all organic materials will remain bioavailable, losses will promote local biomass growth and eventual carbon sequestration. Positioning permeable enclosures at the extremities will encourage reuptake of system losses. 

Given the much greater consistency of the growing environment of the equatorial seas, productivity should be higher than the land-based ponds north of the Tropics that have currently been trialed. However, assuming this as a worst case, 6 billion enclosures covering 240,000 sq miles (620 000km²) would match current fossil oil extraction of 100 million barrels per day. The marginal cost of biofuel is expected to be of order $30 per barrel, making this a practical, short-term solution to decarbonize 26% of GHG emissions, without rebuilding the global energy infrastructure in which the World has invested trillions of dollars.