Lessons from energy balances for the production strategies of biofuels

Abstract

Energy balances from photon to biomass can help to assist the optimization of the productivity of algal photobioreactors. These balances identify those processes which decrease the efficiency of biomass production. The presented setup allows to quantify the efficiency of absorption, photochemistry, the metabolic losses and the electron partitioning into the macromolecular pools. The quantitative estimate of the metabolic losses under optimal and suboptimal conditions (e.g. nutrient limitation or excess light) yields the “real” value for the number of photons needed to transfer one carbon molecule from CO2 into the biomass (P/C value). The experimentally measured values are higher than estimated from the reduction degree of the biomass, especially in the case of proteins and lipids. The reason of this finding is discussed.