III. D.1. Introduction

One of the major accomplishments of the ASP was the development of detailed engineering/cost projections for large-scale microalgae biofuels production. These analyses generally supported the view that microalgae biomass production could be performed at sufficiently low cost as to plausibly become a renewable energy source, assuming however, that the rather ambitious R&D goals of the ASP could be met. A major conclusion from reviewing these studies is that most R&D goals for this technology are related to the algal cultures themselves (productivity, species control, and harvestability), rather than the engineering aspects, such as the ponds, CO2 transfer, or biomass processing.

Historically, the first engineering and cost analysis for large-scale microalgae production of fuels was that of Oswald and Golueke (1960). These authors projected the costs of electricity generated from biogas (methane) obtained from the anaerobic fermentation of algal biomass. The algae were to be cultivated in very large (40-ha) raceway type ponds, mixed with pumps, and supplied with CO2 from a power plant. Other nutrients would come from the digesters. Municipal wastewaters would be used as make up for water and nutrients (C, N, P, etc.). The ponds were to be of earthen construction, with a depth of about 30-cm. Harvesting was assumed to be by simple settling. Electricity costs were projected to be competitive with nuclear power. Although few details were provided, the general concept outlined in this early publication has remained essentially unchanged. Perhaps the greatest change is that biomass productivities thought to be achievable at that time were less than 50 mt/ha/yr of biomass, while current projections are roughly two to five times higher.

With the initiation of the ERDA/DOE funded projects at the University of California-Berkeley during the mid-1970s (Section III. A.), additional engineering and cost analyses were conducted

(Benemann et al. 1977). The early studies were based on large (8-20-ha) ponds, with multiple channels and mixing by recirculation pumps (the required deep concrete sumps and splash pads were a major cost factor). Both the settling pond for harvesting algae by sedimentation and a covered anaerobic lagoon were part of this initial design. Total systems costs were only about $10,000/ha (somewhat over twice that in current dollars). Based on a projected yield of about 500 GJ/ha/y (10 GJ/t of algal biomass) of biogas, costs were projected at about $3/GJ. Although optimistic, this study served as a starting point for more detailed later studies.

I Publications:

Oswald, W. J.; Golueke, C. G. (1960) “Biological transformation of solar energy.” Adv. Appl. Microbiol. 11:223-242.

Benemann, J. R.; Baker, D.; Koopman, B. L.; Oswald, W. J. (1977) “A systems analysis of bioconversion with microalgae.” Proc. Symposium Clean Fuels from Biomass and Wastes, (Klass, D., ed.) Institute of Gas Technology, Chicago, pp. 101-126.