1 An everyday waste problem Food waste separation and collection - PDF document

Energy  electricity  carbon emission Electricity consumption accounted for ~67% of total carbon emission in Hong Kong in 2018. Integrated Food Waste Management with Renewable Energy Production Professor Irene M. C. LO PhD, JP, M.EASA, F.ASCE, F.HKIE, F.HKGSA, M.AEE, CAP, BEAM Pro, GB Faculty Chair Professor of Civil and Environmental Engineering Academician, European Academy of Sciences and Arts Hong Kong University of Hong Kong University of 14 June 2018 1 2 2 Science and Technology Science and Technology Fuel mix of electricity production in HK Carbon emission from different energy sources Others 3% CO 2 e (g/kWh) Coal Nuclear 46% Coal -fired (Castle Peak Power Station) 975 23% Gas -fired (Black Point Power Station) 414 Nuclear power (Daya Bay Nuclear Power Plant) 0 Renewable energy (solar, wind) 0 Natural Gas Renewable energy from waste-to-energy facility 28% Low CO 2 e (e.g. anaerobic digestion/co-digestion, incineration, landfill) Need to explore the potential RE from WTE facility in HK due to its lower impact on climate change Hong Kong University of Hong Kong University of Source: Environment Bureau, 2014 3 4 Science and Technology Science and Technology 1

An everyday waste problem … Food waste separation and collection How to collect food waste efficiently and effectively ? Waste disposed of at landfills in HK Waste Tonnes/day Municipal SolidWaste 9,000 (in which 40% is food (3600) waste ) ConstructionWaste 3,350 Photo courtesy of Environment Bureau Sewage Sludge 950 simple sorting with less OtherWastes 200 behavioral change ! Total : 13,500 Hong Kong University of 6 5 Science and Technology Advanced technology for food waste Optical sorting plant in Oslo, Norway collection -optic bag system • Haraldrud Plant  In operation Food waste Optic bag (green bag) since 2009 Refuse collection vehicle • The world’s Common plastic bag or largest optical Garbage bin Other MSW designated bag if MSW charging sorting plant scheme by bag is launched  Handles wastes Refuse transfer station approximately 150,000 OWTF Packed food waste tonnes/year Video courtesy of Envac Company IWTF Optical sorting system Other packed MSW Hong Kong University of Hong Kong University of 7 8 Science and Technology Science and Technology 2

(Co-)digestion of food waste with sewage Biogas Production from Anaerobic Digestion of Sludge at 4 Secondary STWs in 2013 in HK sludge for biogas generation 500 tonne/day Yuen Shatin Tai Po Shek Wu Food waste Parameters Long STW STW Hui STW Anaerobic digestion (OWTF)  Food STW separated from other waste Biogas generation Treated Sewage 85 36 31 10 (million m 3 ) MSW in RTS Biogas produced 5.6 2.0 1.2 0.6 A portion of food waste can be (million m 3 ) sent to sewage treatment works Source: “ From Sewage to Energy ” presented at HKIE Environmental Division Annual Seminar 2014 and mixed with sewage sludge Using the spare capacity of the 4 STW for anaerobic co- Anaerobic Wastewater Biogas Sewage co- digestion, it is estimated that 500-600 tpd food waste can treatment sludge generation digestion be handled (based on HRT of 22 days and sludge to food waste ratio of 10 : 3 by mass). Hong Kong University of Hong Kong University of 9 10 10 Science and Technology Science and Technology Food waste  biogas  various energy forms Potential renewable energy in Hong Kong % of total electricity Sources of Renewable Energy consumption in 2014 (total = 43,932 GWh) Anaerobic digestion Electricity 1 Sewage sludge incineration facility at Nim Wan 0.4% Organic waste treatment 2 Municipal solid waste incineration at Shek Kwu Chau 1.45% facility (OWTF) Biogas 3 Food waste (assume 80% recovery) – Biogas 1.67% generated from AD at organic waste treatment facility 4 Anaerobic co-digestion of sewage sludge & food waste 0.43% Food waste City gas for biogas generated at 2 secondary STWs + 3 new cavern STWs Anaerobic Petrol; co-digestion 5 Landfill gas recovery with 3 landfill extension 0.7% Diesel; 6 Wind (Lamma Winds, proposed Offshore Wind Farm) 1.2% LPG Sludge digester at STWs Total 5.85% Biogas fuel Hong Kong University of Hong Kong University of 11 12 Science and Technology Science and Technology 3

Comparison of life cycle carbon emission from Example: Linköping in Sweden food waste valorization options Food waste CO 2 e produces (g/kWh) biogas fuel to Food waste valorization to replace CLP electricity 23 ~6% of the vehicle use in Food waste valorization to replace Towngas 148 Linkoping Biogas-fueled bus station Food waste valorization to replace petrol as vehicle fuel -181 * Food waste valorization to replace diesel as vehicle fuel -149 * Food waste valorization to replace LPG as vehicle fuel -125 * * A negative value indicates a better environmental performance. It means that the avoided carbon emission from the fuel substitution exceed the direct emission from the processes of biofuel production. Biogas-fueled car Biogas-fueled bus Biogas waste truck fleet Source: Woon et al., 2016. (Values are recalculated with unit conversion) Hong Kong University of Hong Kong University of 13 13 14 Science and Technology Science and Technology More examples of cities turning food waste How can it be implemented in Hong Kong? into biogas fuel for vehicle use! Bern, Switzerland Stockholm, Sweden Biogas-fueled cars (i.e., hybrid gas cars) Government service cars Private cars Haarlem, the Netherlands Oslo, Norway ~1,000 tpd food waste  Fuel ~12,000 private cars/day Public  Reduce ~ 130,000 tonne transport CO 2 /year Hong Kong University of Hong Kong University of 15 16 Science and Technology Science and Technology 4

HKUST Conclusions  Simple yet effective food waste separation and collection system  optic bag system  Valorization of food waste to renewable energy: AD & Co-AD  Renewable biogas: electricity, city gas, and biogas fuel for vehicle use (1) Recycling 80% food waste can further achieve ~30% of waste reduction target; (1) Producing renewable energy; (3) Creating low carbon economy (waste into business). Hong Kong University of Hong Kong University of 17 18 Science and Technology Science and Technology Advantages of optic bag system • Enable separation at source with less behavioral change Optic bag (HKD • Eliminate the need for extra 0.1/bag based storage space for the waste on Swedish fractions case) • Perform recycling in existing Growth of environmental industry & business in buildings Korea is highly related to the environmental policy Hong Kong University of 20 Science and Technology 5