Historically, algae have been seen as a promising source of protein and have been ac­tively cultured by humans for centuries, mainly for food. Growing algae as a source of protein on a large scale in open ponds was first conceived by German scientists during World War II (Soeder 1986). The first attempt in the USA to translate the biological requirements for algal growth into engineering specifications for a large — scale plant was made at the Stanford Research Institute (1948-1950). During 1951, Arthur D. Little made a further advance through the construction and operation of a Chlorella pilot plant for the Carnegie Institute (Burlew 1953). These studies even­tually provided some of the most comprehensive early information on the growth, physiology, and biochemistry of algae.

Under certain growth conditions, many microalgae can produce lipids that are suitable for conversion into liquid transportation fuels. In the late 1940s, nitrogen limitation was reported to significantly influence microalgal lipid storage. Spoehr and Milner (1949) published detailed information on the effects of environmental conditions on algal composition and described the effect of varying nitrogen supply on the lipid and chlorophyll content of Chlorella and some diatoms. Investigations by Collyer and Fogg (1955) demonstrated that the fatty acid content of most green algae was between 10 and 30% DCW. Werner (1966) reported an increase in the cellular lipids of a diatom during silicon starvation. Coombs et al. (1967) reported that the lipid content of the diatom Navicula pelliculosa increased by about 60% during a 14-h silicon starvation period. In addition to nutrition, fatty acid and lipid composition and content were also found to be influenced by a number of other factors such as light (Constantopolous and Bloch 1967; Nichols 1965; Pohl and Wagner 1972; Rosenberg and Gouaux 1967) and low temperatures (Ackman et al. 1968). With the advent of the oil embargo in the early 1970s, a search for alternative energy sources set the stage for an almost 20-year research effort devoted to biofuel production from algal lipids.