Solar Energy Perspectives - IEA
Solar Energy Perspectives - IEA
Solar Energy Perspectives - IEA
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Chapter 9: <strong>Solar</strong> fuels<br />
<strong>Solar</strong> gasification of biomass, if syngas is further converted into CO 2 and hydrogen, could<br />
possibly offer the cheapest non-fossil option, benefitting from the energy content of both the<br />
solar flux and the biomass.<br />
Hydrogen from CSP could be used in today’s energy system by being blended with natural<br />
gas. Town gas, which prevailed before natural gas spread out, included up to 60% of<br />
hydrogen (in volume), or about 20% in energy content. This blend could be used for various<br />
purposes in industry, households and transportation, reducing emissions of CO 2 and nitrous<br />
oxides. Gas turbines in integrated gasification combined cycle (IGCC) power plants can burn<br />
a mix of gases with 90% hydrogen in volume.<br />
<strong>Solar</strong> hydrogen could also find niche markets today in replacing hydrogen production from<br />
steam reforming of natural gas in its current uses, such as manufacturing fertilizers and<br />
removing sulphur from petroleum products.<br />
One of the major uses of hydrogen in industry today is the desulphuration of oil. Regenerating<br />
hydrogen with heat from concentrated sunlight to decompose hydrogen sulphide into<br />
hydrogen and sulphur, could save significant amounts of still gas in refineries for other<br />
purposes.<br />
Coal could be used together with gas as feedstock, and deliver dimethyl ether (DME). One<br />
molecule of methane, one molecule of carbon (coal) and two molecules of water would be<br />
recombined as two molecules of DME, after solar-assisted steam reforming of natural gas,<br />
coal gasification under oxygen, and two-step water splitting. This scheme is currently being<br />
considered in China for coal liquefaction as some of the coal-richest Chinese regions such as<br />
Qinghai, Xinjang, Shaanxi and the Ordos area in Inner Mongolia offer enough direct normal<br />
irradiance for concentrating solar power. DME could be used as a liquid fuel, and its<br />
combustion would entail similar CO 2<br />
emissions to those from burning conventional<br />
petroleum products, but significantly less than the life-cycle emissions of other coal-to-liquid<br />
fuels.<br />
Solid and liquid biofuels enhanced from solar heat could be used in virtually all transport<br />
and industry applications.<br />
169<br />
© OECD/<strong>IEA</strong>, 2011
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