Solar Energy Perspectives - IEA

Solar Energy Perspectives: Industry and transport
Photo 5.5 PV roof on a plug-in hybrid
Source: Kia Motors America, Inc.
Key point
Vehicles offer surfaces to sunrays that can be used for small electricity generation.
Hydrogen could be another possible vector for introducing solar energy in road transportation.
Liquid fuels made from hydrogen would be an option, offering greater climate change
mitigation potential over unconventional oil with higher associated upstream emissions, and
even more over coal-to-liquid fuels, which entail very high upstream CO 2 emissions unless
these are captured and stored (see Chapter 9). But as such fuels would contain carbon atoms
they would offer only limited emission reductions over kerosene and other petroleum
products from conventional oil.
The use of hydrogen energy chains from renewable electricity could give vehicles greater
range, but with significantly lower energy efficiencies along the chains and, at present, much
higher costs. Carmakers maintain, however, that fuel cell cars could cost ten times less than
today by 2020 (BMW AG et al., 2011). If this reduction is achieved, fuel cell cars will offer
another means of decarbonising road transport. If renewable electricity is the source of
hydrogen, however, it should be considered a variant of electrification, not a means to further
reduce the consumption of petroleum products and associated CO 2
emissions. The outcome
would be different if the source is a concentrating solar process directly producing hydrogen
(as described in Chapter 9). Solar hydrogen might be used more conveniently when blended
with natural gas, as in gas-fired power plants.
Aviation and marine transportation have good prospects for energy efficiency improvements,
but limited options for switching away from fossil fuels, beyond biofuels and solar fuels. PV
can provide small fuel savings, as most new cargo ships include on-board electricity
generation and electric propellers. Wind power, with automatic sails or kites, could save
more significant amounts of fuels in certain applications. Unmanned planes, however, could
sustain very long aerial watching missions at low speed thanks to PV cells – an emerging
niche market that recalls the pioneer role of PV in satellites. Global positioning systems,
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© OECD/IEA, 2011