7.4.7.1 Production processes, emissions and emission intensities

The main production processes for the food industry are almost identical, involving preparatory stages including crushing, processing/refining, drying and packaging. Most produce process residuals, which typically go to waste. Food production requires electricity, process steam and thermal energy, which in most cases are produced from fossil fuels. The major GHG emissions from the food industry are CO₂ from fossil fuel combustion in boilers and furnaces, CH₄ (GWP=21 (IPCC, 1995)) and N₂O (GWP = 310 (IPCC, 1995)) from waste water systems.

The largest source of food industry emissions is CH₄ from waste water treatment, which could be recovered for energy generation. For example, the Malaysian palm oil industry emits an estimated 5.17 MtCO₂-eq (1.4 MtC-eq) from open-ponding systems that could generate 2.25 GWh of electricity while significantly reducing GHG emissions (Yeoh, 2004). Emissions from the Thai starch industry (Cohen, 2001) are estimated at 370 ktCO₂-eq/yr (101 ktC-eq/yr), 88% were from waste water treatment, 8% from combustion of fuel oil and 4% from grid electricity. Although individual food industry factory emissions are low, their cumulative effect is significant in view of the large numbers of factories in both developed and developing countries. Typical energy intensities estimated at about 11 GJ/t for edible oils, 5 GJ/t for sugar and 10 GJ/t for canning operations (UNIDO, 2002).

7.4.7.2 Mitigation opportunities

The most important mitigation opportunities to reduce food industry GHG emissions in the near- and medium-term include technology and processes related to good housekeeping and improved management, improvements in both cross-cutting systems (e.g., boilers, steam and hot water distribution, pumps, compressors and fans) and process-specific technologies, improved process controls, more efficient process designs and process integration (Galitsky et al., 2001), cogeneration to produce electricity for own use and export (Cornland, 2001), and anaerobic digestion of residues to produce biogas for electricity generation and/or process steam (Yeoh, 2004). These technologies were discussed in Section 7.3, but some specific food industry applications are presented below.

In Brazil, electricity sales to the grid from bagasse cogene-ration reached 1.6 TWh in 2005 from an installed capacity of 400 MW. This capacity is expected to increase to 1000 MW with implementation of a government-induced voluntary industry programme (Moreira, 2006). In India, the sugar industry has diversified into cogeneration of power and production of fuel ethanol. Cogeneration began in 1993–1994, and as of 2004 reached 680 MW. Full industry potential is estimated at 3500 MW. In 2001, India instituted a mixed fuel programme requiring use of a 5% ethanol blend, which will create an annual demand for 500 M litres of ethanol (Balasubramaniam, 2005).

Application of traditional boilers with improved combustion and CEST (Condensing Extraction Steam Turbines) in the southern African sugar industry could produce surpluses of 135 MW for irrigation purposes and 1620 MW for export to the national grid (Yamba and Matsika, 2003) in 2010. Sims (2002) found that if all 31 of Australia’s existing sugar mills were converted to CEST technology, they could generate 20 TWh/yr of electricity and reduce emissions by 16 MtCO₂/yr (4.4 MtC/yr), assuming they replaced coal-fired electricity generation. Gasifying the biomass and using it in combined cycle gas turbine could double the CO₂ savings (Cornland, 2001). Proposed CDM projects in the Malaysian palm oil industry (UNDP, 2002), and the Thai starch industry (Cohen, 2001) demonstrated that use of advanced anaerobic methane reactors to produce electricity would yield a GHG emission reduction of 56 to 325 ktCO₂-eq/yr (15 to 90 MtC-eq/yr). Application of improved energy management practices in the coconut industry (Kumar et al., 2003) and bakery industry (Kannan and Boy, 2003) showed significant saving of 40 to 60 % in energy consumption for the former and a modest saving of 6.5% for the latter. In the long term, use of residue biomass generated from the food industry in state-of-the-art Biomass Integrated Gasifier Combined Cycle (BIG/CC) technologies, could double electricity generation and GHG savings compared to CEST technology (Yamba and Matsika, 2003; Cornland et al., 2001).

Virtually all countries have environmental regulations of varied stringency, which require installations including the food industry to limit final effluent BOD (Biochemical Oxygen Demand) in the waste water before discharge into waterways. Such measures are compelling industries to use more efficient waste water treatment systems. The recently introduced EU-directive requiring Best Available Techniques (BAT) as a condition for environmental permits in the fruit and vegetable processing industry (Dersden et al., 2002) will compel EU industry in this sector to introduce improved waste water purification processes thereby reducing fugitive emissions due to anaerobic reactions.