algae

Fast-growing, oil-producing species of microalgae have become the focus of attention for both biomass and biodiesel biofuels, but questions remain about scalability, economics, and the competition between large-scale microalgae cultivation and agriculture, with regard to water, fertilizer, and land use. By cultivating microalgae on domestic wastewater, the water and fertilizer problems can be overcome, and by using algae for improved wastewater treatment, economic and environmental benefits can be realized. Land use for traditional large-scale algae cultivation systems, open ponds and closed photobioreactors (PBRs), continues to be a formidable challenge, however.
Assuming that algae production must be linked to existing wastewater treatment facilities and given that these facilities are deeply embedded in urban infrastructure, the integration of algae production into exiting urban infrastructure is both prohibitive in cost and unrealistic to implement. Alternatively, installing algae production in remote locations at great distances from the wastewater facilities requires significant investments in pipelines and transport infrastructures as well as in energy for pumping water and delivering materials. Could the solution for a practical and affordable large-scale algae production system, linked to wastewater treatment be located offshore, at least for coastal cities?
We propose a system called OMEGA (Offshore Membrane Enclosures for Growing Algae), consisting of floating photobioreactors (PBRs) made of flexible plastic sheets welded into a series of interconnected chambers. The modular PBRs are attached to each other to form a system that is attached to moorings or tethered to piers. If necessary, the system is protected by a breakwater.
The OMEGA PBRs are filled with secondary-treated wastewater redirected from established outfalls and inoculated with oil-producing freshwater algae. Nearby Power Plants or other sources of fossil fuel combustion provide CO2 to stimulate algae growth. Unlike land-based PBRs, which require significant energy input for mixing and temperature control, OMEGA uses surface waves for mixing and the heat capacity of the surrounding water for temperature control. The salinity difference between wastewater and seawater is used for forward osmosis, which 1) concentrates nutrients in the wastewater, stimulating algae growth; 2) dewaters the algae, facilitating harvesting; and 3) cleans the wastewater released into the surrounding environment. If the cultivated freshwater algae accidentally escape into the surrounding, seawater they pose no threat to the marine environment, as they cannot survive in saltwater.
While the proposed OMEGA system overcomes many of the difficulties inherent in existing land-based algae cultivation, there remain long-standing challenges in biology, engineering, environmental impact, and politics. Some of these challenges are associated with algae cultivation in general (e.g., growth control, grazers, pathogens, and dewatering) and others with OMEGA in particular (e.g., materials, permitting, fouling, marine mammals). These issues and others are under investigation as part of an OMEGA feasibility study supported by grants from NASA ARMD and the California Energy Commission. The purpose of this paper is to evaluate if indeed the future of algae biofuels is offshore?

Meeting the Energy Independence and Security Act (EISA) renewable fuels goals requires development
of a large sustainable domestic supply of diverse biomass feedstocks. Macroalgae, also known as
seaweed, could be a potential contributor toward this goal. This resource would be grown in marine
waters under U.S. jurisdiction and would not compete with existing land-based energy crops.
Very little analysis has been done on this resource to date. This report provides information needed for an
initial assessment of the development of macroalgae as a feedstock for the biofuels industry.
The findings suggest that the marine biomass resource potential for the United States is very high based
on the surface area of the marine waters of the U.S. and rates of commercial macroalgae production in
other parts of the world. However, macroalgae cultivation for fuels production is likely a long term effort.
Analysis of the available data showed that considerable scale up in cultivation over current world-wide
production and improvements in processing throughout the supply chain are needed.
Despite the high resource potential, the United States does not currently have a macroalgae production
industry and would have to develop this capability. In order to meet current renewable fuels goals, the
scale of the effort would have to be high in comparison with activity in other parts of the world. For
example, replacing 1% of the domestic gasoline supply with macroalgae would require annual production
rates about ten and one-half times current worldwide production. This could be accomplished through
cultivation on 10,895 km2 of ocean surface, based on current rates of production reported for the
international macroalgae cultivation industry. Advances in cultivation technology already being tested
could potentially increase production from three to ten fold with a corresponding decrease in the area
needed for cultivation to meet specified production goals. While it is no surprise that the cost estimates to
produce fuel from macroalgae are currently high, it should be noted that this is based on a limited amount
of available data and that production costs for macroalgae can benefit from increased efficiency and scale.
A thorough analysis is warranted due to the size of this biomass resource and the need to consider all
potential sources of feedstock to meet current biomass production goals. Understanding how to harness
this untapped biomass resource will require additional research and development. A detailed assessment
of environmental resources, cultivation and harvesting technology, conversion to fuels, connectivity with
existing energy supply chains, and the associated economic and life cycle analyses will facilitate
evaluation of this potentially important biomass resource.

This model was developed at Idaho National Laboratory and focuses on crop production. This model is an agricultural cultivation and production model, but can be used to estimate biomass crop yields.

The Decision Support System for Agriculture (DSS4Ag) is an expert system being developed by the Site-Specific Technologies for Agriculture (SST4Ag) precision farming research project at the INEEL. DSS4Ag uses state-of-the-art artificial intelligence and computer science technologies to make spatially variable, site-specific,
economically optimum decisions on fertilizer use. The DSS4Ag has an open architecture that allows for external input and addition of new requirements and integrates its results with existing agricultural systems’ infrastructures. The DSS4Ag reflects a paradigm shift in the information revolution in agriculture that is precision farming.