Transcribed
Technology pathways to transform biomass into biofuel.
2.3.5 Technology pathways to transform biomass into biofuel Sources of biomass Feedstocks Conversion process Products Chemical Oilseed Transesterification Biodiesel or Fats and oils crops renewable diesel Hydrotreating Grains Starches Bi ological Conventional al cohol Sugar crops Sugars Ethanol, butanol fermentation Enzymatic hydrolysis and fermentation Anaerobic digestion Methane Agricultural residues Novel approaches Cellulose hemicellulose and lignin Thermochemical Trees and grasses Hydrocarbons and Руrolysis natural oils from which desired fuel Algae Gasification can be produced Catalyst to liquid fuels Third generation eg gosoline or diesel equivalents, syngas, and hydrogen Source: Pena 2008.
Technology pathways to transform biomass into biofuel.
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Biomass combustion is a carbon-free process because the resulting CO2 was previously captured by the plants being combusted. At present, biomass co-firing in modern coal power plants with efficiencies...
up to 45% is the most cost-effective biomass use for power generation.
The technical process for transforming biomass to biofuels
is shown in Figure 2.3.5. The first generation of biofuels were made from the oil, starch, and sugar contained in cultivated crops. More recently, the technology improved to extract
cellulose from non-edible vegetation—a second generation of biofuels—which minimizes competition with food
production. The latest, third-generation technology, still at a
pilot stage, uses algae grown in water bodies to avoid land-use competition. Ethanol and biodiesel are the main biofuels and can be added to gasoline and diesel.
It has been about 10 years since the US and Europe
implemented various policies and incentives to promote biofuel production. According to Agriculture Outlook 2012,
co-published by the Organisation for Economic Co-operation
and Development and the Food and Agriculture Organization of the United Nations, 65% of EU vegetable oil, 50% of
Brazilian sugarcane, and about 40% of US maize production is used as feedstock for biofuel production. During 2009–2011,
global production of ethanol averaged 98.2 billion liters (equal
to 8.6% of gasoline use by volume) and of biodiesel 21.3 billion liters (3.1% of diesel). High global oil prices have been a major
factor behind such high production, which is projected to double by 2021. The leading Asian producers of ethanol are the PRC at 8,094 million liters, India at 1,976 million liters, and Thailand at 777 million liters, and of biodiesel Thailand at 664 million liters, Malaysia at 563 million liters, and Indonesia at 397 million liters.
However, the current generation of biofuels has three significant problems. First, biomass cultivation, transportation, and processing requires energy that must be subtracted from biofuel energy content to
arrive at net energy output. The net energy ratio, or energy available in biofuel per unit of energy used to produce it, is lowest converting maize to ethanol. Depending on the production process, the ratio is
four times or more for cellulosic biomass and biodiesel. Second, the
first-generation biofuels compete with food production by directly using
food crops or land used to grow them. With its large poor population,
Asia already faces challenges producing enough affordable food. Food
security could be jeopardized if too many farmers chose to switch to
biofuel crops. Third, biofuels are not yet cost-competitive with traditional
transportation fuels, typically requiring significant subsidies.
Research is under way worldwide to address the first two issues
by producing biofuels from materials that do not compete with food
production, using the so-called “cellulosics” in crop residues, plants with
high-energy content that grow well on degraded land, and algae. At this
point these technologies are not yet cost-competitive, but if they reach
fruition they could make a substantial contribution. In the meantime,
according to the IEA, ethanol from sugarcane currently being produced
in Brazil and Thailand, shows significant potential to mitigate GHG
emission, if no indirect land-use change occurs (IEA 2011c). The analysis
shows lifecycle net GHG gains from using biofuels made from palm
oil produced in Indonesia and Malaysia, the world’s largest producers.
However, other analyses conclude that net gains from biofuel production
are illusory owing to land-use changes to support their production
(EPA 2012).
As with solar and wind, biofuels other than ethanol are not yet costcompetitive.
The IEA shows the cost of producing conventional biodiesel
in 2011 at nearly double that of gasoline and projects it remaining
more expensive than gasoline for the foreseeable future. On the other
hand, the IEA projects ethanol costs falling below gasoline costs before
2020 because of scale expansion and efficiency improvements. Thirdgeneration
biofuels from cellulosics, both ethanol and biodiesel, are
not projected to become cost-competitive with gasoline until sometime
around 2030 (IEA 2011c). In lieu of cost-competitiveness, the rapid growth of biofuel production in Asia and elsewhere has been driven by biofuel subsidies. In Asia, the governments of the PRC, Indonesia, and Malaysia in particular provide subsidies. One study estimated that biofuels subsidies in the PRC in 2006
amounted to $115 million, or roughly $0.40/liter, and projected that such
subsidies would reach about $1.8 billion by 2020 (International Institute for Sustainable Development 2008). The study found comparably large biofuels subsidies for Indonesia in 2006–2008. In sum, the prospects of biofuels improving energy supply adequacy and environmental sustainability depend heavily, as with solar and wind, on aggressive investment in new technologies that will reduce their cost
and overcome land-use conflicts.
Source : IEA Biomass - http://www.iea.org/publications/freepublications/publication/name,3738,en.html
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