A high-resolution, spatially explicit estimate of fossil-fuel CO2 emissions from the Tokyo Metropolis, Japan

doi:10.21203/rs.3.rs-17565/v2

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A high-resolution, spatially explicit estimate of fossil-fuel CO₂ emissions from the Tokyo Metropolis, Japan

https://doi.org/10.21203/rs.3.rs-17565/v2

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Background: The quantification of urban greenhouse gas (GHG) emissions is an important task in combating climate change. Emission inventories that include spatially explicit emission estimates facilitate the accurate tracking of emission changes, identification of emission sources, and formulation of policies for climate-change mitigation. Many currently available gridded emission estimates are based on the disaggregation of country- or state-wide emission estimates, which may be useful in describing city-wide emissions but are of limited value in tracking changes at subnational levels. Urban GHG emissions should therefore be quantified with a true bottom-up approach.

Results: Multi-resolution, spatially explicit estimates of fossil-fuel carbon dioxide (FFCO2 ) emissions from the Tokyo Metropolis, Japan, were derived. Spatially explicit emission data were collected for point (e.g., power plants and waste incinerators), line (mostly traffic), and area (e.g., residential and commercial areas) sources. Emissions were mapped on the basis of emission rates calculated for source locations. Activity, emissions, and spatial data were integrated, and the results were visualized using a geographic information system approach.

Conclusions: The annual total FFCO2 emissions from the Tokyo Metropolis in 2014 were 44,855 Gg CO2 , with the road-transportation sector (16,323 Gg CO2 ) accounting for 36.4% of the total. Spatial emission patterns were verified via a comparison with the East Asian Air Pollutant Emission Grid Database for Japan (EAGrid-Japan), which demonstrated the applicability of this methodology to other prefectures and therefore the entire country.

Environmental Policy

Carbon dioxide

CO2 emission inventory

Fossil fuel

GIS

High-resolution map

Tokyo emissions

Table 1 Spatial data used for identifying CO₂ emission sources, and other data used for counting emissions for each sector in Tokyo. Note that several sectors are not consistent with the IPCC definitions. For example, (1) only the LTO cycle emissions were used here for civil aviation, whereas the IPCC sector includes emissions from LTO cycle and cruise; (2) only passenger and cargo ships with round trips to the ports were considered here for the waterborne navigation sector, whereas the IPCC sector covers all water-borne transport, from recreational craft to large ocean-going cargo ships; and (3) two IPCC sectors (manufacturing and commercial sectors) were combined to form the industrial and commercial sector.

Emission sector (IPCC sector code)	Source type	Spatial information	Activity and spatial data	Emission factor
Electricity generation (1A1ai)	Point	Center points of chimneys of power plants (latitude, longitude)	Capacity and generation types of fossil-fuel power generation [17–20], and running ratio [21]	Emission factors of fossil-fuel power generation [22, 23]
Civil aviation (1A3a)	Point	Representative points of runways at airports (latitude, longitude)	Annual flight numbers [24], aircraft types, engine types, number of engines [25-33], and flight timetables [34, 35]	Energy consumption intensity of aircraft by engine type [16, 36, 37]
Waterborne navigation (1A3d)	Point	Representative points of buildings at ports (latitude, longitude)	Load factors, fuel consumption time [38, 39], and trips by vessels [40, 41]	Emission factors of vessels by vessel type [23, 38, 39]
Waste incineration (4C1)	Point	Center points of chimneys at waste incineration plants (latitude, longitude)	CA consumption rate [42], MSW combustion amount [43], industrial waste combustion amount [44], and disposal capacity [45]	Emission factors of fossil-carbon content by type [23]
Road transportation (1A3bi, 1A3bii, and 1A3biii)	Line	Length (m), width, and road types of the central road lanes	Traffic conditions [46], road lengths from DRM [47], and administrative map of Tokyo [48]	Emission factors of vehicles by vehicle speed and type [49]
Industrial and commercial (1A1aiii, 1A2, 1A4a, and 1A4ciii)	Area	Site area (m²), height, and number of floors in industrial and commercial buildings	Worker numbers [52], energy-balance table [53], land use map of Tokyo [55], DSM [56], and building polygons and DEM [57]	Emission factors of workers by industry category [52, 53]
Residential (1A4b)	Area	Site area (m²), height, and number of floors in residential buildings	Land use map of Tokyo [55], DSM [56], building polygons and DEM [57], and household occupancy [58]	Emission factors of households by building type and occupancy [59]
Agricultural machinery use (1A4cii)	Area	Area of cultivated lands by crop type (area)	Administrative map of Tokyo [48], area of cultivated land by crop type [60, 61], and high-resolution land use map [64]	Emission factors of farmlands by crop type [62, 63]

Table 2 CO₂ emission factors for vehicles by vehicle type and speed (2010), extracted from experimental results [49].

Speed (km h^–1)	CO₂ emission factors for small vehicles (10^–9 Gg CO₂ km^–1 per vehicle)	CO₂ emission factors for large vehicles (10^–9 Gg CO₂ km^–1 per vehicle)
5	437.1	1,646
10	328.8	1,372
15	237.1	1,099
20	209.8	1,014
25	187.5	928.7
30	171.3	855.7
35	158.9	793.7
40	149.5	741.9
45	142.2	700.1
50	136.9	667.9
55	133.2	645.4
60	131.1	632.3
65	130.3	628.6
70	130.9	634.3
75	132.8	649.3
80	135.9	673.6
85	140.2	707.2
90	145.6	750.1

Table 3 Annual consumption of fossil fuels, worker numbers, and CO₂ emission factors for workers by category in Tokyo, derived from the 2014 economic census [52] and the energy-balance table for Tokyo (2014) [53].

Category	Fossil fuel consumption (Terajoules)	Annual emissions (Gg CO₂ yr^–1)	Total number of workers	CO₂ emission factors 10^–3 Gg CO₂ yr^–1 per worker)
Forestry and Fishery	4.6	16.9	4,151	4.1
Mining, Quarrying of Stone and Gravel	13.0	47.6	2,090	22.8
Construction Industry	234.0	857.9	465,553	1.8
Manufacturing, Auto Power Generation	730.2	2,678	713,594	3.8
Electricity, Gas, Heat Supply and Water	22.5	82.5	33,666	2.5
Information and Communications	67.2	246.3	833,221	0.3
Transport and Postal Activities	178.9	656.1	484,149	1.4
Wholesale and Retail Trade	329.2	1,207	1,996,425	0.6
Finance and Insurance	21.4	78.4	403,625	0.2
Real Estate and Goods Rental and Leasing	169.5	621.7	345,959	1.8
Scientific Research, Professional and Technical Services	70.6	258.7	474,795	0.5
Accommodation, Eating and Drinking Services	506.9	1,859	890,005	2.1
Living-Related and Personal Services and Amusement Services	369.4	1,354	353,091	3.8
Education, Learning Support	206.0	755.3	468,565	1.6
Medical, Health Care and Welfare	358.3	1,314	861,346	1.5
Compound Services	1.3	4.7	37,754	0.1
Miscellaneous Services	208.9	766.1	1,030,901	0.7
Government	79.0	289.6	258,416	1.1

Table 4 CO₂ emission factors for households by occupancy and building type, based on an investigation of residential energy consumption [59].

Household size (occupancy)	CO₂ emission factors for detached buildings (10^–3 Gg CO₂yr^–1 per household)			CO₂ emission factors for collective buildings (10^–3 Gg CO₂yr^–1 per household)
Household size (occupancy)	City gas	Liquefied petroleum gas	Kerosene	City gas	Liquefied petroleum gas	Kerosene
1	0.234	0.132	0.334	0.240	0.085	0.032
2	0.564	0.159	0.452	0.654	0.110	0.056
3	0.706	0.209	0.387	0.929	0.074	0.071
4 or more	0.809	0.257	0.379	1.120	0.106	0.069

Table 5 CO₂ emission factors for farmland by crop type [62, 63].

Crop type	Emission factor (10^–6 Gg CO₂ ha^–1 yr^–1)
Rice cultivation	597.9
Wheat	727.7
Corn	338.0
Potato	719.3
Sweet potato	751.2
Red bean	414.6
Green soybean	499.7
Green tea	550.3
Japanese radish	922.8
Cabbage	1,488.2
Japanese mustard spinach	286.3
Italian ryegrass	458.5
Greenhouse tomato	124,200
Open-field tomato	1,744.2
Kosui Asian pear	1,330.5

Table 6 Estimates of annual CO₂ emissions from Tokyo (2014) by sector and source type.

Sectors	IPCC sector code	Sectoral emissions (Gg CO₂ yr^–1)	Emission source type	Total emissions (Gg CO₂ yr^–1)
Electricity generation	1A1ai	6,478	Point source	10,119
Civil aviation	1A3a	1,879
Waterborne navigation	1A3d	279
Waste incineration	4C1	1,483
Road transportation	1A3bi, 1A3bii, and 1A3biii	16,323	Line source	16,323
Industrial and commercial	1A1aiii, 1A2, 1A4a, and 1A4ciii	13,085	Area source	18,413
Residential	1A4b	5,302
Agricultural machine use	1A4cii	26
Total	-	44,855

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A high-resolution, spatially explicit estimate of fossil-fuel CO₂ emissions from the Tokyo Metropolis, Japan

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