Bubble Farming: Scalable Microcosms for Diatom Biofuel and the Next Green Revolution

There are two standard ways of growing microalgae for biofuel: open raceways and closed photobioreactors. Open raceways are relatively inexpensive, but are subject to airborne and exotic species contamination, requiring large amounts of relatively flat land, and constant energy input for water circulation and stirring. Closed photobioreactors are more expensive, can accumulate biofilms on the inside of the clear tubing that block light from reaching all of the algae inside, are closed to gas exchange with the atmosphere, and require frequent maintenance. We propose that bubble farming using bubble wrap solves these problems. Each water filled bubble is a microcosm isolated from the environment, except for input of sunlight and gas exchange with the atmosphere above and the soil below, yielding a carbon negative footprint. The modular design reduces losses from contamination and physical damage and makes bubble farming scalable to large areas of land with variable topography. With appropriate plastics, water would be retained, thereby eliminating both maintenance and watering. Each bubble could be prepackaged with a dry inoculum of algae (adapted to local conditions), minerals and nutrients, per agricultural seed suppliers. Using combine-scale equipment to be developed, the farmer would lay the bubble wrap onto the ground while each bubble is injected with water, sealed, and left in place until harvest time. The initial aim is biomass for extraction of biofuel. The long range goal is to develop an alga, probably a diatom, which spontaneously secretes alkanes that would separate gravitationally inside each bubble for direct harvesting of biofuel. Bubble farming is compatible with secondary plant crops located below the bubble wrap, such as nitrogen fixers, or could be used on non-arable or fallowed land, improving rather than compromising this valuable resource. Unlike permanent open raceways and photobioreactors, bubble farming could be included in crop rotation schedules. Given the massive scale of plastics currently used in farming, the development of equipment for large-scale bubble farming should be realizable. Through the achievement of targeted benefits of recyclability and economies of scale, the use of bubble wrap has the potential to reduce the cost of biofuels below that of fossil fuels. It may also be applicable to growing crops that thrive in hydroponic or aquaponics settings, and if so, many food crops could also be grown via bubble farming, protected from drought, insects and pathogens.