The main purpose of this project was to compile and update the 2016 Taiwan National Greenhouse Gas Inventory of Waste Sector using the recommended methodologies in 2006 Intergovernmental Panel on Climate Change Guidelines for National Greenhouse Gas Inventories (IPCC 2006 Guidelines). The total emission of the waste sector in 2016 was 4,108.8 kt-CO2 eq. Among the waste sector emissions, the largest contributor was domestic wastewater treatment accounting for 37.9%, followed by industrial wastewater treatment accounting for 34.2%, solid waste disposal accounting for 23.6%, incineration of waste accounting for 3.4%, and biological treatment of waste accounting for 0.9%. Breakdown of emissions in 2016 by GHG showed that the largest contributor to the emissions was CH4 accounting for 88.6%, followed by N2O accounting for 8.2 %, and CO2 accounting for 3.2%. In addition to National Greenhouse Gas Inventory updation of Waste Sector, other results of this project were as followed:
1. Evaluate and analyze 7 National Inventory Report of Annex I parties in 2018 to understand and identify the latest international trends, emission trends and characteristics, and focal points of inventory review reports. Furthermore, the European and the U.S. policies towards circular economy, initiatives of biogas recovery and reusing, emission parameters, and other strategies and evaluation of achieving GHG emission reduction targets were also reviewed for developing waste management strategies.
2. Visited 6 domestic wastewater treatment plants and 5 industrial wastewater treatment plants to identify the benefits of biogas recovery for CH4 emission reduction. Implementation of Taiwan government biogas recovery system for wastewater treatment will provides 35.8% emission reduction potential from domestic wastewater treatment plants and 40.3% emission reduction potential from industrial wastewater treatment plants.
3. Measure on-site GHG emissions of each wastewater treatment process in paper industry and food manufacturing industry, so as to establish the country-specific industry emission factors. Through analyze of the measure results, the emission factors of paper industry in Taiwan is 1.23×10-3 kg CH4/kg COD and 3.50×10-5 kg N2O/kg-N (Weighted arithmetic mean). On the other hand, the wastewater samples of food manufacturing industry in Taiwan is still insufficient for reviewing and establishing emission factors.
4. Study the methodologies and emission parameters for estimating CH4 and N2O emissions from domestic wastewater treatment and CH4 emissions from industrial wastewater treatment. Relative to the previous estimation, CH4 emission from domestic wastewater treatment in 2016 will reduce 28.2 % and N2O will reduce 49.3%. Besides, CH4 emissions from industrial wastewater treatment will also reduce 43.4%.
5. Implement uncertainty analysis of waste sector emissions in 2016 using “propagation of error method” and “Monte Carlo method”, and analyze the uncertainty trend from 2014 to 2016. The uncertainty analysis results of waste sector total emission by Monte Carlo method will reduce 3.8% negative deviation and 1.9% positive deviation in comparative to propagation of error method.
6. Hold 3 expert meetings to confirm probable reduction benefits and suggestions of biogas recovery from wastewater treatment plants, and reviewing the rationality of country-specific emission factors for industrial wastewater treatment plants.
7. Assist Taiwan EPA to compile National Greenhouse Gas Inventory of Waste Sector from 1990 to 2016, and submit the related estimation results to the National Greenhouse Gas Inventory platform.