Investigating the Energy Potential from Co-firing Coal with Municipal Solid Waste

Abstract

With the increasing population and economic development of Mauritius, the demand of electricity increases each year. This has brought a significant rise in the consumption level of fossil fuels to meet these demands. Currently, the increasing prices of fossil fuels on the international market are having severe repercussion on the economy of the country.
There are around 444, 570 tons of municipal solid waste (MSW) generated per year in Mauritius and this amount is giving rise to disposal problem. One of the disposal options could be the generation of electricity through combustion of the waste. At the same time, there are several coal power plant in the country that generate both heat and power. This study was, therefore, initiated to investigate the effect of co-firing MSW and coal. Proximate and ultimate analyses were conducted on both MSW and coal. The optimum blending ratio of MSW and coal was found to be 80 % MSW and 20 % coal by mass that is 1119 tons per day of MSW. The electrical output from the mixture of MSW and coal was 51 MW out of which 29.7 MW was generated from MSW only which represent around 58 % of the total produced power of the plant. Total cost saving from this co-firing project is estimated at 456 million Mauritian Rupees (MUR). The MSW has a lower heating value, however, it was seen that pollutant emission was reduced in the co-firing process. Gaseous pollutant emissions like CO2 was reduced significantly at this blending ratio compared to firing coal solely. Greenhouse gases (GHG) emissions were reduced on two counts: firstly reducing combustion of coal and secondly avoiding methane emission at the landfill site, which is equivalent to around 1.92 million Metric tonnes of CO2 equivalent annually.
The findings from this study showed that MSW could be a good renewable fuel for co-firing with coal combustion. It reduces both the amount of land allocated annually for landfilling and the dependence on fossil fuels.

Keywords: co-firing, municipal solid waste, coal, GHG reduction