This invention provides a method using light of different wavelengths to estimate freshwater and marine algae growth stage and algae growth rates as well as lipid content in standard media. Light absorption by the algae is measured for a specified light intensity in each of two or more narrow wavelength ranges, correcting for absorption in the medium without algae. The net light absorption is compared with a reference set of absorption values for the algae at different growth stages.
An algorithm is applied to estimate growth stage based on differences between measured absorption values and reference absorption values. Similarly, lipid content is estimated based on measured values compared to a reference set of values for lipids in algae at specific growth stages.
Repeated measurements of the light beam absorption in each of two or more wavelength ranges, and comparisons with reference values, determine changes in the algae growth stage, the growth rate, and estimated lipid content. For applications focused on maximizing lipid content, algae growth is terminated when lipid content has reached a maximum. One or more relevant environmental parameters (light intensity or wavelength, temperature, or nutrients) may be varied to optimize the lipid production of the algae and the time required to reach that production level.
This invention provides simultaneous information about algae growth and lipid content, and does not depend solely on the time of growth. It implicitly includes variables due to environmental parameters such as nutrient deprivation or other stresses.