Environmental impact assessment of energy recovery from food waste in Singapore
comparing biogas production to incineration
As a small and land scarce country, effective waste management is ofoutmost importance in Singapore. In this study the production of biogasthrough anaerobic digestion from the organic fraction of municipal solidwaste (OFMSW) was compared to incineration of the waste. At the momentalmost all of the OFMSW in Singapore is incinerated. Three differentscenarios were compared to the reference scenario (incineration): one with alarge scale biogas plant that can treat half of all OFMSW in Singapore, onewith a medium scale biogas plant about 15 times smaller than the large oneand one with a small scale biogas plant that can treat waste from e.g. ashopping center or a food center.By using life cycle assessment (LCA) the different scenarios were comparedin terms of global warming potential (GWP), acidification, eutrophication,energy use and land use. Two alternatives for utilization of the biogas werealso compared through LCA, generation of electricity and the use of thebiogas in heavy vehicles.From an environmental perspective production of biogas is a better way totreat OFMSW than incineration. When biogas is used for electricitygeneration the impact on GWP decreased about 80-130 CO2-eq/toncompared to the incineration scenario and also has lower impact onacidification and eutrophication. The result also showed that the use of thegas as a vehicle fuel gives about the same impact on GWP as when the gasis used to generate electricity but a much lower impact on both acidificationand eutrophication. In terms of scale, the medium and large scale plantshave less environmental impact than the small scale plant when the gas isused as a vehicle fuel. When the gas is used to generate electricity, the smallscale scenario had higher GWP but lower acidification and eutrophication.The prevention of leakage of biogas during production and upgrading iscrucial for the environmental impact on GWP. A leakage of only a fewpercent of the produced gas will lead to a loss of all the gain in saved greenhouse gas emissions.