III. A.1. Introduction

The concept of microalgae biomass production for conversion to fuels (biogas) was first suggested in the early 1950s (Meier 1955). Shortly thereafter, Golueke and coworkers at the University of California-Berkeley demonstrated, at the laboratory scale, the concept of using microalgae as a substrate for anaerobic digestion, and the reuse of the digester effluent as a source of nutrients (Golueke et al. 1957; Golueke and Oswald 1959).

Oswald and Golueke (1960) presented a conceptual analysis of this process, in which large (40- ha) ponds would be used to grow microalgae. The algae would be digested to methane gas used to produce electricity. The residues of the digestions and the flue gas from the power plant would be recycled to the ponds to grow additional batches of algal biomass. Wastewaters would provide makeup water and nutrients. The authors predicted that microalgae biomass production of electricity could be cost-competitive with nuclear energy.

This concept was revived in the early 1970s with the start of the energy crisis. The National Science Foundation-Research Applied to National Needs Program (NSF-RANN) supported a laboratory study of microalgae fermentations to methane gas (Uziel et al. 1975). Using both fresh and dried biomass of six algal species, roughly 60% of algal biomass energy content converted to methane gas.

With the establishment of ERDA, the NSF-RANN activities were transferred to this new agency, which initiated a program in biomass fuels production. The Fuels from Biomass Program at ERDA funded a new project at Berkeley to develop a microalgae wastewater treatment and fuel production process. This project, started in 1976, was carried out at the Richmond Field Station of the University of California-Berkeley, and continued for about 4 years in parallel with several related projects. These projects included an ERDA-funded biophotolysis project (reviewed in Benemann et al. 1980), a NSF-RANN project on N-fixing blue-green algae (cyanobacteria) for fertilizer production (Benemann et al. 1977), and an EPA-funded project on algal bioflocculation in oxidation ponds (Koopman et al.1978; 1980).

The initial objective of the ERDA microalgae fuels project was to develop methods by which particular species of microalgae could be maintained in open ponds used for wastewater treatment. There are many large (>100 ha) and many hundreds of smaller wastewater treatment pond systems in California and elsewhere in the United States. The problem addressed by this project was the removal (harvesting) of the algal biomass from the effluents. Not only did the algal biomass represent a potential resource for the production of biogas, but the algal solids discharged from the ponds were pollutants that resulted in eutrophication and dissolved O2 reduction in the receiving bodies of waters. Thus, there was considerable interest in lower-cost and less energy-intensive microalgae harvesting technologies and wastewater treatment processesn general. In the absence of cost-effective microalgae harvesting technologies, microalgae pond systems, although widely used, could not meet the increasingly stringent wastewater treatment plant discharge standards, specifically in regards to suspended solids (mainly algal cells). A process that could reduce algal solids in pond effluents would have a ready market and potential near-term applications.

This was the justification for the initial emphasis on wastewater treatment processes from microalgae production. However, the ERDA/DOE Fuels from Biomass Program soon shifted its emphasis towards large-scale biomass production systems, having multi-quad (quad = 1015 Btu) impacts. This accounted, in part, for the early emphasis by this program on large-scale biomass “energy plantations” and even immense ocean energy farms, which some thought would provide solutions for the perceived U. S. energy crisis (Benemann 1980).

Large effects on U. S. energy supplies would probably not be plausible with wastewater treatment systems, which in aggregate represent a maximum potential of perhaps only one- or two-tenths of a quad of fuels (Benemann et al.1998, in preparation), a fraction of 1% of U. S. energy needs. However, wastewater systems can arguably serve as an initial step in the long-term development of larger, stand-alone systems. Although this argument was controversial at the time, the Univeristy of California-Berkeley project continued to emphasize wastewater treatment systems in its R&D. However, the supporting economic analyses carried out by the ASP (see Section

III. D.), started to focus on very large-scale, stand-alone systems. Section III. A. of this report reviews the algal mass-culture projects that were supported by ERDA and DOE before the ASP was initiated.