Fræðaþing landbúnaðarins - 06.02.2004, Blaðsíða 125

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In addition to being considered carbon neutral (zero emissions), because biomass
conversions only emit the amount of CO2 that is sequestered, the process does not
increase net CO2 levels in the atmosphere. Methanol produced from biomass has,
furthermore, been found to emit between 40 - 80% less greenhouse gas (GHG)
emissions than methanol produced from natural gas and emit less particulate matter,
carbon monoxide and hydroxide (CEC 2000, see Table 1).
Table 1. Total GHG emissions of fuel cell vehicles using methanol produced from
biomass andfrom natural gasfor afamily car (5 seats) (Ohlström et al. 2001)
Process g C02 (eq)/km
Methanol produced from natural gas 117
Methanol produced from biomass 6
Reformulated gasoline including MTBE from biomass 185
Reformulated diesel from cmde oil 111
Hybrid vehicles - 85% methanol from biomass blended with 15% gasoline 117
Hybrid vehicles - 85% methanol from natural gas blended with 15% gasoline 145
Conversion of Biomass Resources
Biomass can be used to generate energy in several ways: the traditional approach of
direct combustion for heat as energy, as well as from new emerging techniques -
production of biodiesels from crops rich in organic oils (such as sunflower),
production of alcohols (from beetroot, wheat, shorgum, etc), and production of
methanol from wood wastes and forest residues.
Much of the research emphasis in renewable energy resource production has focused
on using agricultural crops or wastes to produce liquid fuels by fermentation
processes (e.g., ethanol). This approach has been further expanded to include the
production of heating materials and even cloth (Cargill-Dow 2000, Hettenhaus et al.
2000, Brown 2003, Kopetz 2003; many others). Conversion of agricultural products
(e.g., sugar cane, com) to ethanol for mixing with gasoline has been practiced for
some time, and this practice has even been institutionalised in countries like Brazil
(Mancini 1998). The use of agricultural biomass and organic wastes to produce
ethanol is a well-established and commercialised industry in many countries.
Similarly, wood is now being considered as the initial raw material for ethanol
production. In the US, the feasibility of using wood to produce ethanol is also being
considered to replace methyl-tert butyl ether (MTBE) as a gasoline oxygenate additive
for gasoline. Biodiesel can replace fossil diesel fuel in engines without substantial
modifications. The alcohol derivative can be mixed with up to 15% of gasoline
without technical engine modifications (QLG 1997, Nyström and Comland 2003).
The conversion of biomass feed stocks (using wastes from pulp mills) is being
considered to produce methanol as an automotive fuel in a “CO2 neutral” process
(Ohlström et al. 2001). This is driven in part because road transport contributes 85%
of the CO2 emissions generated by the EU transportation sector (Ekbom et al. 2003).
Methodologies for conversion of biomass to energy need to be further developed to
maximize effíciency and environmental quality. We suggest that the contribution of
wood to energy production has the potential to increase significantly if wood were to
be transformed using green or sustainable practices. At present, wood is mainly being