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| Image by EMSL via Flickr |
A biorefinery is a facility that
integrates biomass conversion processes and equipment to produce fuels,
power, and value-added chemicals from biomass. The biorefinery concept
is analogous to today’s petroleum refinery, which produces multiple
fuels and products from petroleum.By producing several products, a
biorefinery takes advantage of the various components in biomass and
their intermediates, therefore maximizing the value derived from the
biomass feedstock. A biorefinery could, for example, produce one or
several low-volume, but high-value, chemical products and a low-value,
but high-volume liquid transportation fuel such as biodiesel or
bioethanol. At the same time, it can generate electricity and process
heat, through CHP technology, for its own use and perhaps enough for
sale of electricity to the local utility. The high value products
increase profitability, the high-volume fuel helps meet energy needs,
and the power production helps to lower energy costs and reduce GHG
emissions from traditional power plant facilities.
There are several platforms which can be
employed in biorefineries with the major ones being the sugar platform
and the thermochemical platform (also known as syngas platform). Sugar
platform biorefineries breaks down biomass into different types of
component sugars for fermentation or other biological processing into
various fuels and chemicals. On the other hand, thermochemical
biorefineries transform biomass into synthesis gas (hydrogen and carbon
monoxide) or pyrolysis oil.
The thermochemical biomass conversion
process is complex, and uses components, configurations, and operating
conditions that are more typical of petroleum refining. Biomass is
converted into syngas, and syngas is converted into an ethanol-rich
mixture. However, syngas created from biomass contains contaminants such
as tar and sulphur that interfere with the conversion of the syngas
into products. These contaminants can be removed by tar-reforming
catalysts and catalytic reforming processes. This not only cleans the
syngas, it also creates more of it, improving process economics and
ultimately cutting the cost of the resulting ethanol.
