The use of additives and fuel blending to reduce emissions from the combustion of agricultural fuels in small scale boilers

• Peat as a fuel blend can reduce ash melting and particulate related problems
• High N content of peat leads to increased NOx emissions.
• Kaolin has significant potential as a PM1 reduction tool.
• Fuel indices can characterise fuels PM1 emission and ash melting temperatures.
• Additives and blends can make agri-residues suitable for use in domestic boilers.

The results of tests to determine the efficacy of fuel blending and additives to reduce emissions from the combustion of agricultural fuels are presented. It was shown that peat blended with miscanthus and tall fescue has the potential to significantly reduce both PM1 emissions and problems related to ash melting. However, the high nitrogen content of the peat (1.5%) compared to the two agricultural fuels tested (miscanthus – 0.33 and tall fescue- 0.69) leads to increased NOx emission with increasing proportions of peat in the blend. The results also showed that for both fuels a kaolin addition rate of 4% gave significant reductions in PM1 emissions. With increasing peat/kaolin addition ash sintering temperature increased while potassium release decreased. With further developments in the use of additives and fuel blending it is foreseen that pellets from agricultural fuels may form a viable alternative to wood pellets.