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statistics and carbon analysis informatics for biofuels


opposite is true: the available data volume is huge, and only a small fraction of it can be manageably handled. In the case of greenhouse gasses it all


started with two observation stations, on Hawaii and Antarctica, 50 years ago. The Keeling curve showed both a remarkably regular annual planetary respiration cycle which, when statistically smoothed, revealed a clear rising curve in residual atmospheric carbon dioxide. Half a century on, those two observation stations have become 120 or so but, as Manning et al[2]


comment,


this is ‘very small... compared to the several thousand surface temperature monitoring stations, and... geographic gaps in the measurement network signifi cantly hinder scientifi c investigation and understanding of the carbon cycle and carbon-climate interactions’. Attention has widened from carbon dioxide to embrace methane and other pollutants, become a matter of political public attention, but only a couple of hundred scientists worldwide are directly involved in measuring or studying their levels distribution. They do, of course,


showing reductions in cost, primary energy consumption (PEC) and carbon dioxide emission (CDE) under different strategies for integrating organic Rankine cycle heat sources with combined power, heat and optionally cooling systems


Selected summary results from Hueffed and Mago[10]


a way to remove greenhouse gasses from the atmosphere, but raising new questions. Solution of carbon dioxide in seawater reduces pH values and alters the carbonate


ALL FINDINGS IN THIS AREA ARE PROJECTIONS, STANDING OR


FALLING ON THE RELIABILITY OF MODELLING AND ANALYTIC METHODS USED TO BRIDGE THE GAP


have access to computerised analytics unimaginable to Charles David Keeling as the 1950s tipped over into the 60s, but there are still limits to what can be done. All fi ndings in this area are projections, standing or falling on the reliability of modelling and analytic methods used to bridge the gap. All of which brings us back to carbon


quota trading. Quotas are based on aggregated upward reporting of emissions from the externality producer level, but the resulting fi gures don’t match those assembled from atmospheric monitoring. The discrepancy isn’t surprising. Quite apart from vested interest[3]


chemistry of seawater. One result of this is to retard calcifi cation, though there has been little concrete research into the extent to which this affects ocean organisms (see ‘Musselling in on the action’). Ideally, the best sinks are functional replacements for lost land-based photosynthesis and this is an area where a lot of data analytic effort is focused. UN Food and Agriculture Organisation


(FAO) statistical estimates, compiled from producer and national reporting, suggest[4] that emissions attributable as externalities to production of lamb produced in New


in minimising


estimates, the range of industrial emission sources is wide: from leaky gas pipelines to agriculture. They also include complex mixed carbon equity effects such as clearance of carbon sink forest to create arable farmland, which consumes fuels and artifi cial fertilisers, but also serves to provide partial photosynthetic carbon sequestration in its turn. Carbon sinks, which capture carbon


compounds from the atmosphere and lock them up for a time, are one side of the equation. The oceans are suggested as a potential carbon capture sink, offering


www.scientific-computing.com


Zealand for UK consumption break down as roughly 80 per cent incurred during ‘birth to farm gate’ production, 12 per cent in the retail and consumption parts of the chain, 5 per cent on transport, and 3 per cent during processing. While a reduction of 5 per cent is well worth making, this shows that transport (the ‘food miles’ often quoted) is a long way from being the biggest issue in livestock farming carbon reduction. Sheep farming is a relatively low-impact sector; in cattle farming the production phase is more emission-intensive still. Since nothing seems likely to slow the


global shift towards meat and dairy diets, investigation of the ways to reduce their carbon footprints is a major focus of attention. One approach is to investigate ways of increasing the carbon sequestration potential of crops, whether for human or livestock consumption. Researchers in New Zealand and Scotland are, for instance, running very similar GenStat mediated statistical studies designed to assess the effects of different factors from root depth to planting dates. Root depth, bulk and longevity turns


out to be one critical issue. Most crops go through a cycle in which they grow (locking up carbon through photosynthesis) and are harvested (usually for their above ground leaves or fruits) and cease to function. The parts of their structures that are below ground thus become carbon repositories, gradually decomposing to become part of the soil and thus nutrients for further plant growth. It would be nice, as Douglas Kell of the Manchester Interdisciplinary Biocentre recently[5]


commented, to be able Map from Manning et al[2] showing ground-


based sampling stations, which measure both atmospheric carbon dioxide and methane concentrations (magenta symbols) or carbon dioxide only (cyan symbols)


to tie carbon capture to root density in a single precise quantitative relation but, of course, life isn’t like that. Once again the linkage is statistical, summarising a large range of variables (initial carbon levels, photosynthetic conversion rates, microbial activity, soil aridity and stability, to pick just a few) in a gradation of likelihood bands. The range covered by the resulting estimates is very large, although most of them cluster between 0.3 and 0.8 tonnes of carbon sequestered per hectare per year. Of course this capture is not permanent (with time the root structures decay and the carbon is respired back into the air), but it is a time lock on a signifi cant carbon mass. Data analysis shows that the carbon content of soils just within the United Kingdom varies by more than 1,500 per cent from site to site, and that the intensity and longevity of the effect is strongly linked to depth, bulk and durability of the root structures. Since


DECEMBER 2011/JANUARY 2012 13


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