Fræðaþing landbúnaðarins - 06.02.2004, Síða 126

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used as the sole fuel source in cogeneration plants (e.g., electricity, low-pressure
steam production) and for heat/power generation by co-firing with coal or other fossil
fuel sources. Conversion to sustainable options such as linking biomass generation of
methanol to H has the potential to reduce GHG emissions by 80-90% over current
practices (Makinen and Sipilá 2003).
Emerging Opportunities in Linking Biomass Conversions to Hydrogen Fuel Cell
Systems
The practice of using biomass to produce methanol has only recently been suggested
as a fuel source for hydrogen fuel cells (Sigurdardottir et. al. 2003, Vogt et al. 2004).
Sigurdardottir et. al. (2003) and Vogt et. al. (2004) proposed a system which
potentially can increase the use of biomass as a renewable resource in decentralized
energy production systems that generate electricity using H fuels cells (see figure 1).
Methanol is the key liquid fuel driving rapid developments in fuel cell technology
(Methanex 2003, IdaTech 2003, The Economist 23/10/97 & 22/04/99). While
traditionally methanol is mostly produced from natural gas, a non-renewable resource
(Kheshgi et al. 2000), wood based processes being developed today are becoming
more sophisticated and efficient, for example, flash pyrolysis and hydrothermal
liquefaction (Bridgewater 1999, TNO 2003). As recent as the 1990s, methanol
production from wood was considered economically not viable since it was less
expensive to produce it from natural gas (Sedjo 1997, Ohlström et al. 2001). Several
factors are changing the economic accounting scenarios of the past: inclusion of
environment sustainability and security factors as part of cost/benefit analyses, tax
incentives/carbon tax on energy production (implemented in Sweden, Austria, others),
regulations mandating the increase in the proportion of energy consumed from
renewable resources to mitigate GHG emissions (CEC 1997, FAO 2002).
Using forests or agricultural resources and wastes to generate altemative energy is
optimal, as renewable resources are being used, and biomass conversions can be made
using environmentally sound chemical practices. These practices can also provide
environmental services such as maintaining forest nutrient status by reapplying the
residues from biomass conversion processes on the site (Andersson and Emilsson
2003). Mákinen and Sipilá (2003) suggested ethanol and biodiesel are short-term
solutions for acquiring biofuels and that the most significant GHG emission
reductions will likely come from using methanol and hydrogen fuel cell systems.
Wood has a more consistent chemical composition, it a more efficient and reliable
starting material to produce methanol (Brown 2003). Wood can be used as a starting
material to produce methanol using one of two main processes: 1) gasification, and 2)
pyrolysis. In the past 10 years, much engineering research and development are
allowing the commercialization of biomass conversion systems. In particular,
European countries, such as The Netherlands, Finland, Sweden, and Germany, have
been very active in this area. While not yet perfected, gasification or pyrolysis of
biomass efficiently produces a liquid fuel such as methanol.
A system for transforming forest biomass to methanol on a small scale has not been
commercialized to date, but is a logical goal since wood is a higher quality, starting
material with a more consistent chemical composition than many other types of
biomass. These qualities make wood a more reliable material to transform to
methanol. The efficiency of chemical conversion and the resulting products will vary