Scope for significant GHG emissions cut in agriculture

At the same time as the United Nations Framework Convention on Climate Change (UNFCCC) conference on Climate Change opened in Poznan, a new report on building a low carbon economy was published on Monday, 1st December, by the Government’s Committee on Climate Change, chaired by Lord Turner. The Soil Association welcomed the announcement by Lord Turner that there is ‘scope for significant emissions cuts in agriculture’. Peter Melchett, the Soil Association director said ‘we share Lord Turner’s apparent disappointment that so little has been done to look for options to reduce greenhouse gas (GHG) emissions in agriculture. When the food we buy accounts for 30% of our personal carbon footprint we think it’s a scandal that, in the Committee on Climate Change’s words, ‘the policy framework for delivering abatement (from farming) is underdeveloped’. This means the government have neglected the climate change impact of food and farming, and the Soil Association welcomes the fact that the Committee on Climate Change will be making this a priority over the next 12 months. How might this be achieved? Read on and find out.

One of the options for reducing GHG emissions from agriculture is to treat organic waste by digestion and to capture the biogases produced during digestion. As I read the press statement item in the Soil Association page I remembered a book entitled ‘Biofuels for Fuel Cells: renewable energy from biomass fermentation’, to which I contributed a chapter and which is abstracted in CAB Abstracts. In chapter 2, Boeriu et al. reported that 170 Gton of biomass is produced through photosynthesis in green plants, of which only 6 Gton is being cultivated (of the cultivated approximately 62% is used as food, 3% non-food uses and 33% for fuel/energy and housing). Agricultural residues from primary agricultural production, such as straw, foliage and hulls amount to about 5 Gton/year. These residues are a source of biogas, which should be captured and converted to energy. Feedstocks for bioenergy plants can include residues from agriculture and forestry. In fact there is a company in Iowa, USA (BFC Gas and Electric) which has been producing biogas from agricultural residues and other wastes since 1995.

New agricultural waste regulations came into force on 15 May 2006 and affect whether or not farmers can burn, bury, store and use their waste on the farm or send it elsewhere. This means farmers had to stop using farm tip/dump and burning plastics and other materials. Farmers had until 15 May 2007 to comply with the new rules and to register for any agricultural waste exemptions. The Environment Agency published guidelines on how to handle waste, specifically for farmers. One of the options is biological treatment, and composting is suggested as an example.  Part 2 of the book I mentioned above deals with biomass fermentation, including systems design. One interesting system is described to obtain hydrogen gas from potato peel. Biomass digestion by anaerobic digestion produces gases such as methane and hydrogen.

According to the International Energy Agency, bio-energy offers the possibility to meet 50% of our world energy needs in the 21st Century. Therefore, the Committee on Climate Change should be looking into ways of capturing biogas from agricultural organic wastes for use as energy and thus reduce GHG emissions and carbon footprint from the agricultural sector. My chapter (Chapter 23) in Biofuels for fuel Cells describes processes for cleaning up biogases to remove the poisonous hydrogen sulphide, which is produced during protein degradation, in order to obtain pipeline quality biogas. Please also search CAB Abstracts and the Environmental Impact database for more material on climate change and waste reduction. For example, waste digestion technology used for biogas production in Germany back in 2006 is shown in this article in the CAB Abstracts database.

 

References

Lens, P. Westermann, P; Haberbauer, M. & Moreno, A. (2005). Biofuels for Fuel Cells: renewable energy from biomass fermentation. London, IWA Publishing.

IEA Bioenergy. http://www.ieabioenergy.com

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