Global biofuel potential

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

The global potential of conventional and emerging biofuels is limited by land availability for energy crops as well as the high cost of most existing and emerging conversion technologies (see also Chapter 7). In terms of land availability, estimates 

Although a high theoretical potential of RES exists, this potential decreases significantly when further restrictions, such as the technical availability, market constraints, environmental constraints and the economic feasibility of renewable technology options for energy conversion, are taken into account. For these reasons, it is also hard to predict how renewable capacities will develop in the future. 

Biofuel Fuel derived from organic sources, e.g., biogas, biomass and the biodegradable fraction of waste. The use of biofuel is neutral in terms of carbon dioxide emissions. 

Biomass Forestry and agricultural crops and residues used as fuel. Energy crops are grown specifically as a biomass fuel. 

---

The LCA study of ethanol focused on the evaluation of (GHG) emissions. Meanwhile, Life Cycle Impact Assessment (LCIA) studied the impacts (eg, global warming potential, ozone depletion, acidification potential) resulting from the LCI study. Finally, depending on the results obtained in the LCI and/or LCIA, many suggestions and recommendations can be offered. GHG emissions of biofuels are expressed per MJ of unit output. 

Together with Arvin Mosier, Keith Smith, and Wilfned Winiwarter I showed in 2008 that currently used methods of biofuel production (bio-ethanol and bio-diesel) could cause the atmospheric release of N2O in an amount that can wipe out any advantages provided by savings in the emissions of fossil fuel derived CO2, This is possible due to the large global warming potential of N2O, a product of fertilizer application. Earlier studies severely underestimated the importance of the N2O production. 

Worldwatch Institute (2007). Biofuels for Transport Global Potential and Implications for Sustainable Agriculture and Energy in the 21st Century. Earthscan Publications, Ltd. 

The potential of biomass to make a large contribution towards replacing conventional fuels is constrained by land availability and competition with other end-use sectors. In particular, the potential for oil seeds to generate FAME is limited. Generally, yields of biofuels from purpose-grown crops depend on the species, soil type and climate.22 At a global level, it is estimated that biofuels could substitute up... 

There is a consensus amongst scientists that biofuels used in a sustainable manner result in no net increase in atmospheric carbon dioxide (CO ). Some would even go as far as to declare that sustainable use of biomass will result in a net decrease in atmospheric CO (Jefferson et al., 1991). This is based on the assumption that all the COj given off by the use of biomass fuels was recently taken in from the atmosphere by photosynthesis. Increased substitution of fossil fuels with biomass-based fuels would therefore help reduce the potential for global warming, caused by increased atmospheric concentrations of COj. 

World Watch Institute, Biofuels for Transport. Global Potential for Sustainable Energy and Transport, Earthscan, London, Sterling, 2007. 

---