Performance and Impact of Macroalgae Farming
Marine macroalgae, also referred to as seaweeds or kelp, are a group of exceptionally diverse aquatic plants. Macroalgae can be found along nearly all coastlines around the globe and in some cases also in the open ocean. They have traditionally been used for food and feed, as well as fertilizer. In 2016, the world produced approximately 26 million wet metric tons of seaweed, primarily through highly labor-intensive farming techniques. While macroalgae production has increased six-fold over the past quarter-century, the current state of macroalgae “mariculture” is not capable of achieving the scale, efficiency and production costs necessary to support a seaweed-to-fuels industry. Dramatically increasing productivity will require significant advancements in the domestication of macroalgae and new farming technologies. To accelerate the development of critical tools and technologies, the MARINER program is supporting projects in five areas: 1) Integrated Cultivation & Harvest System Design, 2) Critical Enabling Components, 3) Computational Modeling, 4) Monitoring Tools, and 5) Breeding & Genomic Tools.
Project Innovation + Advantages:
Makai Ocean Engineering will lead a MARINER Category 3 project to develop tools to simulate the biological and structural performance of offshore macroalgae systems. Macroalgae farming systems will require significant capital and operating costs. Investment and management decisions can be guided by the development of advanced modeling tools to help better understand the nature of macroalgae production for profitable operation. Makai's project will result in a hydrodynamic-mechanical model which simulates forces on offshore algae structures from to waves and currents. Output from the model will be used to size primary components of the offshore systems, and to create cost estimates based on these components. Several scenarios will be modeled for varying wave sizes, water depths, and currents, and thus the results will inform trends in system cost versus oceanographic conditions. These trends will be used to determine the capital cost required per hectare of farm. Additionally, a three-dimensional and time-varying ocean circulation and biological algae model will be developed to simulate the transport, mixing, and consumption of nutrients and resulting algae growth rates. Multiple algae farm configurations will be modeled to gain an understanding of the tradeoffs between system size and nutrient supply requirements. Modeling tools like Makai's system will be critical for designing macroalgae farm components and systems which meet target costs and harvest yields to make them commercial viable and scalable.
If successful, MARINER projects strive to develop the tools needed to allow the United States to become a world leader in marine biomass production for multiple important applications, including the production of biofuels.
Production of biofuels and bioenergy from domestically produced marine biomass could ensure that the U.S. has at its disposal a scalable, domestic source of low-carbon energy supplies.
Growing large amounts of macroalgae would not compete with land-based food crops, requires no fresh water and can be grown without the addition of energy-intensive, synthetic nitrogen fertilizer. Large-scale macroalgae cultivation may help reduce the negative effects of nutrient overload and ocean acidification in many coastal ocean regions.
A domestic macroalgae industry would not only create a valuable new source of domestic energy, but also create significant new economic and employment opportunities in many waterfront communities along the U.S. coasts from Maine to the Gulf of Mexico, Alaska, and the Pacific Islands.