11.08.2015   Biofuels for Road Transport

Solar Conversion Efficiencies of Physical Methods

Besides biological processes, there are also physical conversion processes for solar energy. Efficiencies for a number of physical methods of converting solar radiation into heat, H2 or electricity are in Table 2.3. It can be seen that solar conversion efficiencies of photovoltaic cells are much higher than the conversion efficiencies for the transport biofuels in Table 2.2.

Table 2.3 Efficiencies for the conversion of solar radiation to electricity or heat

Type of conversion

Output

Conversion

efficiency

Correction factor for fossil fuel input into conversion apparatus (MJ output — fossil fuel input/MJ output)

Overall

energy

efficiency

(%)

Photovoltaic

silicon

(Mohr et al. 2007; Fthenakis et al. 2008)

Electricity

-14

0.75-0.8

-10.5-12

Hybrid

photovoltaic

silicon/

collector

Electricity/

heat

15%

(electricity)

+40% heat (He et al. 2006; Tripanagnostopoulos et al. 2006)

0.9-0.95

49.5-52

Photovoltaic

III-V

Electricity

15-30

(Green et al. 2003)

0.8-0.9 (dependent on insolation)

(Meijer et al. 2003; Mohr et al. 2007)

12-27

Solar thermal

electricity

turbine

Electricity

10-28% (Mancini et al. 1994)

0.93

(Norton et al. 1998)

9.5-26.5