PHOTOSYNTHETIC EFFICIENCY OF CHLORELLA BIOMASS GROWTH WITH REFERENCE TO SOLAR ENERGY UTILISATION.

The photosynthetic efficiency (PE) of a growing algal culture was determined from the growth yield (Y), that is, biomass produced/light absorbed and the calorific value of the biomass (k); PE equals kY. To obtain the maximum photosynthetic efficiency the algae were grown in light-limited chemostat cultures in urea-mineral salts media plus CO//2 and steady-states were obtained at different specific growth rates. With a given light input the biomass output rate was independent of the specific growth rate up to at least 70% of the maximum specific growth rate. The photosynthetic efficiency was independent of the incident light intensity over the range studied, 5. 3-21. 3 W m** minus **2. The light source had a spectral range of 400-700 nm and its mean wavelength was assumed to be 575 nm.