Photosynthesis energy efficiency

In photosynthesis, absorbed solar radiation is captured as chemical energy. In this spontaneous natural conversion of absorbed solar radiation, the solar energy efficiency ranges from 0.8% for land plants to 6.6% for sea plants. In laboratory experiments efficiencies above 30% have been observed. Table 17.1 summarizes the results of solar energy conversion, as discussed in this chapter and where the value for wind energy creation is given as reported in [14]. 

In 2002, a prominent collection of scientists wrote, Biomass plantations can produce carbon-neutral fuels for power plants or transportation, but photosynthesis has too low a power density ( 6 W/m2) for biofuels to contribute significantly to climate stabilization. These researchers find the scale of our growing energy demand so daunting that they conclude that none of today s current options for renewable energy or energy efficiency are up to the... 

However, from the efficiency point of view, it has to be considered that the biomass formation always requires the conversion of solar energy to some type of biomaterial, and this can be realized only by the photosynthesis process, whose energy efficiency is lower than 1% (see Sect. 1.3). 

Dutton HJ(1997) Carotenoid-sensitized photosynthesis Quantum efficiency, fluorescence and energy transfer. Photosynth Res 52 175-185... 

Total solar energy available on the acre during growing season Photosynthetic efficiency of com plants, i.e., percent of available energy used in photosynthesis Energy equivalent of earth s carbon production Mean solar radiation Photosynthetic efficiency of the world... 

In summary, the initial energy and electron transfer events of photosynthesis are under tight kinetic control. Photosynthesis captures solar energy efficiently because the excited singlet state of chlorophyll is quenched rapidly by processes that occur with time constants that are much shorter than the fluorescence lifetime, which is about 5 ns in diethyl ether at room temperature. 

The maximum efficiency with which photosynthesis can occur has been estimated by several methods. The upper limit has been projected to range from about 8 to 15%, depending on the assumptions made ie, the maximum amount of solar energy trapped as chemical energy in the biomass is 8 to 15% of the energy of the incident solar radiation. The rationale in support of this efficiency limitation helps to point out some aspects of biomass production as they relate to energy appHcations. 

The specific carbon dioxide-fixing mechanism used by a plant will affect the efficiency of photosynthesis, so from an energy utilization standpoint, it... 

In photosynthesis, the reaction involves eight photons for each oxygen molecule, each with an energy of about 1.8 eV (175kJ/mol). Hence the efficiency of... 

Photoinduced ET at liquid-liquid interfaces has been widely recognized as a model system for natural photosynthesis and heterogeneous photocatalysis [114-119]. One of the key aspects of photochemical reactions in these systems is that the efficiency of product separation can be enhanced by differences in solvation energy, diminishing the probability of a back electron-transfer process (see Fig. 11). For instance, Brugger and Gratzel reported that the efficiency of the photoreduction of the amphiphilic methyl viologen by Ru(bpy)3+ is effectively enhanced in the presence of cationic micelles formed by cetyltrimethylammonium chloride [120]. Flash photolysis studies indicated that while the kinetics of the photoinduced reaction,... 

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