Global enviromental issues and biofuel production
Of course we need alternatives to oil. The world uses a cubic mile of petroleum each year, and demand keeps rising as the global economy booms. At first glance, corn seems like a heaven-sent substitute. American corn farmers are the most productive in the world, growing far more of the grain than we can possibly eat, and exporting mountains of the stuff to other countries. And the corn kernel is a marvel of energy storage. Converting that compact bundle of starches into alcohol is a relatively simple trick known to generations of moonshiners. So why not build corn liquor stills on an industrial scale and use the output to power our cars and trucks?
The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, using known global atmospheric removal rates and concentration growth of N2O as a proxy for overall emissions. For both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser production, we find an overall conversion factor of 3–5% from newly fixed N to N2O-N. We assume the same factor to be valid for biofuel production systems. It is covered only in part by the default conversion factor for "direct" emissions from agricultural crop lands (1%) estimated by IPCC (2006), and the default factors for the "indirect" emissions (following volatilization/deposition and leaching/runoff of N: 0.35–0.45%) cited therein. However, as we show in the paper, when additional emissions included in the IPCC methodology, e.g. those from livestock production, are included, the total may not be inconsistent with that given by our "top-down" method. When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warming terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species, have more favourable climate impacts. This analysis only considers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertilizer and pesticide production, but it also neglects the production of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle assessment.
Any copying and distributing the material of Ukrainian Biofuel Portal
without active hyperlink is stricly prohibited !
Link to this news: Global enviromental issues and biofuel production
Copy & Paste This Code to your website:
Views: 5002 Added: 17-01-2009
Tweet
Average Rating:
Global enviromental issues and biofuel production
)
