T.V. Ramachandra^1,2,3,*, Bharath H. Aithal¹, K. Sreejith¹

¹Energy and Wetlands Research Group, Centre for Ecological Sciences(CES), Indian Institute of Science, Bangalore 560 012, INDIA.
²Centre for Sustainable Technologies,
³Centre for infrastructure, Sustainable Transportation and Urban Planning (CiSTUP)
^*Corresponding author: T.V. Ramachandra, cestvr@ces.iisc.ernet.in
Web: http://wgbis.ces.iisc.ernet.in/energy

Results and discussion

4.1 GHG emissions from energy sector: The major energy related emissions considered under this sector are emissions from electricity consumption and fugitive emissions. Emissions resulting from consumption of fossil fuels and electricity in sectors like domestic and industrial are represented independently under specific sectors respectively.

• Electricity Consumption: The major sectors for which greenhouse gases are assessed under electricity consumption are consumption in domestic sector, commercial sector, industrial sector and others (public lighting, advertisement hoardings, railways, public water works and sewerage systems, irrigation and agriculture). Emissions resulting from electricity consumption in domestic sector and industrial sectors are attributed to domestic sector along with the emissions from fuel consumption in this sector and industrial sector along with emissions occurring from industrial processes. GHG emissions from electricity consumption in commercial sector and other sectors are represented in isolation for the comparative analysis among the cities. Emissions resulting from auxiliary power consumption in plants located within the city boundary and from the supply loss is also calculated in this study. Figure 3 illustrates the emissions resulting from electricity consumption in commercial and other sectors along with auxiliary consumption in power plants and supply losses. During the year 2009-10, commercial sector in Delhi consumed 5339.63 MU of electricity resulting in the release of 5428.55 Gg of CO2 equivalent emissions. The emissions hold a share of 29.66% of emissions when compared with emissions from commercial sector in other cities. Electricity consumption in other sub category which includes Delhi International Airport Limited (DIAL), Delhi Jal Board (DJB), Delhi Metro Rail Corporation (DMRC), public lighting, railway traction, agriculture and mushroom cultivation and worship/hospital consumed 2064.73 MU resulting in the emission of 2099.11 Gg of CO2 equivalents, which is responsible for 36.51% of total emissions when compared with other cities. Auxiliary fuel consumption and supply losses resulted in 857.69 Gg of CO2 equivalent emissions accounting for 27.07% of total emissions from this sector. CO2 equivalent emissions from commercial, others and auxiliary consumption and supply losses along with their shares are summarized for all the cities in the table 9.

Table 9:   GHG (CO2 equivalent) emissions from electricity consumption in different cities

Figure 3:   GHG emissions (Carbon dioxide equivalent, CO2 eq) from electricity consumption

Fugitive Emissions: The intentional or unintentional release of greenhouse gases that occurs during the extraction, production, processing or transportation of fossil fuels is known to be fugitive emissions [30]. In the present study fugitive emissions occurring from refinery crude throughput activity is estimated from Greater Mumbai city. The methane (CH4) emissions are found to be 0.0013 Gg for the year 2009-10 which is converted in terms of carbon dioxide (CO2) emissions which gives a value of 0.033 Gg of CO2 equivalents.

4.2       GHG footprint of domestic sector: Domestic sector is a major sector which contributes to the considerable amount of emissions when city level studies are carried out. The major sources include electricity consumption for lighting and other household appliances and consumption of fuel for cooking. In the present study greenhouse gases emitting from electricity consumption in domestic sector and fuel consumption are accounted. The major fuels used in this study are LPG, Piped Natural Gas (PNG) and kerosene based on the availability of data. The chart given below shows the total greenhouse gas (GHG) emissions converted in terms of CO2 equivalent (GHG footprint / aggregated Carbon equivalent of GHG) from the domestic sector in major cities.

In Delhi during the study base year 2009, 11690.43 Gg of CO2 equivalents is emitted from the domestic sector which is the highest among all the cities that accounts for 26.4% of the total emissions when compared with other six cities (Figure 4). Electricity consumption accounted for 9237.73 Gg of emissions out of the total domestic emissions. Earlier estimate sho an emission of 5.35 million tons (5350 Gg) of CO2 emissions from domestic sector in Delhi during the year 2007-08 [206]. Greater Mumbai which covers both Mumbai city and sub urban district emits 8474.32 Gg of CO2 equivalents from the domestic sector which shares 19.14% of the total emissions. Domestic sector in Kolkata results in 6337.11 Gg of CO2 equivalents (14.31% of total emissions). Another major city Chennai ranks second in the list with 8617.29 Gg of CO2 equivalents, contributing to approximately 19.5 % of total emissions share.  Greater Bangalore accounts for an emission of 4273.81 Gg of emissions from domestic sector, 9.65% of total emissions from domestic sector. Hyderabad and Ahmedabad the other two cities are responsible for 2341.81 Gg of CO2 equivalent and 2544.03 Gg of CO2 equivalents respectively. These two cities together share 11% of the total domestic emissions.

Figure 4:   GHG emissions (Carbon dioxide equivalent, CO2 eq) from domestic sector

4.3       GHG footprint of transportation sector: In the major cities transportation sector is one of the major anthropogenic contributors of greenhouse gases [116]. Emissions resulting from total vehicles registered within the city boundary and also from CNG fuelled vehicles present in few of the major cities are calculated. Navigational activities from the port cities are also included in the emissions inventory on the basis of fuel consumption. Delhi leads the emission chart among other cities due to higher emissions because of large number of vehicles. As per the statistics of Transport Department in Delhi, the total number of vehicles in Delhi is more than combined total vehicles in Mumbai, Chennai and Kolkata. Also Delhi has 85 private cars per 1000 population against 8 private cars per 1000 population on all India average. Delhi also has 344868 CNG vehicles during the year 2009-10 [206]. Emissions resulting from road transportation including CNG vehicles and also in port cities of India are as depicted in Figure 5.

Figure 5:   GHG emissions (Carbon dioxide equivalent, CO2 eq) from transportation sector

In Delhi during the year 2009-10, total number of registered vehicles was 6451883, out of which there were around 20 lakhs of cars and jeeps and 40.5 lakhs of motor cycles including scooters and mopeds. CNG fuelled vehicles emitted 1527.03 Gg of CO2 equivalents whereas the remaining vehicles resulted in 10867.51 Gg of emissions contributing almost 30% of the total emissions in this sub category which is the highest among all the major cities. This is twice the earlier estimate of 5.35 million tons (5350 Gg) of CO2 emissions from road transportation sector in Delhi during the year 2007-08 or emissions of 7660 Gg using top down approach  or 8170 Gg using bottom-up approach [204].The CNG vehicles are also present in two other cities: Greater Mumbai and Hyderabad. Emissions from CNG vehicles in Mumbai during the year 2009-10 are found to be 531.34 Gg of CO2 equivalents and for Hyderabad it is estimated that 21.55 Gg of CO2 equivalent was emitted from CNG vehicles during the study year. The emission inventories for transportation sector in all the major cities are given in Table 10.

Table 10:   GHG (CO2 equivalent) emissions from transportation sector in different cities

4.4       GHG footprint of industrial sector: Emissions are estimated from the major industrial processes emitting considerable greenhouse gases which are located within the city boundary (Table 11). Electricity consumption in industrial sector is taken into account using which the resulting emissions are calculated. Fuel consumption data is also used in few of the industries to estimate the emissions. Iron and steel industry, cement industry, fertilizer plants and chemical manufacturing are the few major industries which releases huge amount of greenhouse gases into the atmosphere during the process. Emissions are calculated from the major polluting industries in city boundaries as the data is not available for small and medium scale industries.

Table 11:  GHG (CO2 equivalent) emissions from industrial sector in different cities

Emissions are calculated for ammonia production from the fertilizer industries in Greater Mumbai and Chennai. In Greater Mumbai during the year 2009-10, 654.5 Gg of CO2 equivalents are emitted from the fertilizer industry. Emissions from the fertilizer industry in Chennai are found to be 223.28 Gg of CO2 equivalents from the production of ammonia. Emissions are also calculated from glass industries (Greater Mumbai, Greater Bangalore), paper industry (Kolkata), and petro products (Chennai) using the fuel consumption data. Though this study does not present the entire emissions across industrial sector in a city due to unavailability of data, the major greenhouse gas emitting industries are included in the study along with the electricity consumption which constitutes most of the emissions. Figure 6 shows the emission across different cities.

Figure 6:   GHG emissions (Carbon dioxide equivalent, CO2 eq) from industrial sector

4.5       GHG footprint of agricultural related activities: Methane (CH4) emissions from paddy cultivation, nitrous oxide (N2O) emissions from soil management are the major sectors responsible for greenhouse gas emissions from this sector. Crop residue burning is practiced in few of the Northern parts of the India which also releases GHG emissions. In the current study emission inventory is carried out from these three sectors under agriculture related activities. Table 12 shows the CO2 equivalent emissions resulting from agriculture related activities. Figure 7 shows the pattern of carbon dioxide equivalent emissions in the major cities.

Table 12:  GHG (CO2 equivalent) emissions from agricultural related activities in different cities

Figure 7:   GHG emissions (Carbon dioxide equivalent, CO2 eq) from agricultural related activities

Emissions from paddy cultivation are calculated for two major cities based on the area of paddy fields. Carbon dioxide equivalents (GHG footprint) were found to be 17.05 Gg in Delhi and 5.10 Gg in Greater Bangalore respectively. Emissions resulting from burning of crop residues at the end of growing year are estimated based on Delhi’s emission of 2.68 Gg of CO2 equivalents. N2O emissions are converted into CO2 equivalents as presented in table 12. There are no agricultural activities in most of the cities which indicates decline in agricultural practices as a result of increasing urbanization.

4.6       GHG footprint of livestock management: Enteric fermentation and manure management are the two major activities resulting in the emission of greenhouse gases from animal husbandry. In the present study emissions from livestock management is carried out to calculate the emissions resulting from enteric fermentation and manure management in the major cities. Livestock population for cities is obtained for cities using 2003 and 2007 livestock census, using which the number of livestock is extrapolated to the inventory year 2009 [207, 208]. The emission estimates for the major cities are as given in Table 13.

Delhi and Greater Bangalore are the major cities which emits higher amount of greenhouse gases due to animal husbandry. The emissions resulting from enteric fermentation for Delhi and Greater Bangalore are estimated to be 570.57 Gg of CO2 equivalent and 129.36 Gg of CO2 equivalents respectively. Similarly Delhi and Greater Bangalore emits 43.09 Gg of CO2 equivalent and 10.30 Gg of CO2 equivalent respectively making these two cities higher emitters in the livestock management category among the other cities. Figure 8 shows the emission profile of livestock management for different cities.

Figure 8:  GHG emissions (Carbon dioxide equivalent, CO2 eq) from livestock management

4.7   GHG footprint of waste sector: In the current study greenhouse gas emissions from 3 major waste sectors are calculated: municipal solid waste, domestic waste water and industrial waste water. CH4 emissions from municipal solid waste disposal data are obtained from the local city municipality. CH4 and N2O emissions are calculated from domestic sector. In this study the industrial waste water emissions is calculated for only Kolkata city based on the availability of the data. Table 14 shows city wise CO2 equivalent emissions and their shares in total emissions.

Table 13:   GHG (CO2 equivalent) emissions from livestock management in different cities

Table 14:   GHG (CO2 equivalent) emissions from waste sector in different cities

From the calculations of the present study Delhi emits 853.19 Gg of CO2 equivalents and Greater Mumbai emits 869.92 Gg of CO2 equivalent using IPCC 2006 method [30], both together is responsible for almost 46.7% of the total emissions occurring from solid waste disposal. The emissions depend on the parameters like amount of waste disposed, methane correction factor, degradable organic carbon and oxidation factor [30]. Waste disposal at cities is a major source of anthropogenic CH4 emissions these days. CH4 and N2O emissions from domestic water are calculated on the basis of population of the city. From the current inventories, major emitters from domestic waste water sector are cities Delhi, Greater Mumbai and Greater Bangalore which emit 1378.75 Gg, 1058.09 Gg and 759.29 Gg of CO2 equivalents respectively. Emissions from industrial waste water sector in Kolkata emitted 143.84 Gg of CO2 equivalents during 2009. Waste emission profiles for the major cities are given in Figure 9.

Figure 9:   Carbon dioxide equivalent emissions (CO2 eq) from waste sector

4.8       GHG footprint - Intercity analyses  
Economic activity is a key factor that affects greenhouse gas emissions. Increase in economy results in rise in demand for supply of energy and energy-intensive goods which will also increase the emissions. On the other hand, growth in the economy of a country results in improvement in technologies and promotes the advancement of organizations which aims at environmental protection and mitigation of emissions. In this study, total carbon dioxide equivalent emissions emitted from different major cities are compared with their economic activity, measured in terms of GDP. CO2 equivalent emissions (GHG footprint)  from Delhi, Greater Mumbai, Kolkata, Chennai, Greater Bangalore, Hyderabad and Ahmedabad are found to be 38633.2 Gg, 22783.08 Gg, 14812.10 Gg, 22090.55 Gg, 19796.5 Gg, 13734.59 Gg and 9124.45 Gg respectively. Figure 10 shows the relationship between carbon dioxide equivalent emissions per capita to GDP per capita.

Table 15 gives the values for carbon dioxide equivalent emissions per capita, GDP per capita and carbon dioxide equivalent emissions per GDP for the major cities.

Table 15:   Values of CO2 eq. emissions/capita, GDP/capita and CO2 eq. emissions/GDP for different cities

Chennai emits 4.79 tonnes of CO2 equivalent emissions per capita which is the highest among all the cities, followed by Kolkata which emits 3.29 tonnes of CO2 equivalent emissions per capita. Chennai emits the highest CO2 equivalent emissions per GDP (2.55 tonnes CO2 eq/Lakh Rs.) followed by Greater Bangalore which emits 2.18 tonnes CO2 eq/Lakh Rs. Figure 11 shows the values of carbon dioxide equivalent emissions per GDP and GDP per capita for all the major cities.

Figure 10:   CO2 eq. emissions per capita versus GDP per capita for all the cities

4.9  GHG footprint – city and sector

Aggregation of GHG emissions of all sectors reveal that GHG emissions in major cities in India ranges from 38633.20 Gg/year (Delhi), 22783.08 (Greater Mumbai), 22090.55 (Chennai), 19796.60 (Greater Bangalore), 14812.10 (Kolkata) to 13734.59 (Hyderabad). 

Sector wise GHG footprint analysis for Delhi city (Figure 13) reveals that transport sector leads the carbon emission (32.08%) followed by domestic sector (30.26%) and electricity consumption (19.28%). Electricity consumption (*) includes public lighting, general purpose, temporary and colony lighting. Figure 12, 13, 14 and 15 depicts sector-wise GHG footprint for Delhi, Mumbai, Kolkata and Chennai. In these cities domestic sector has higher GHG footprint ranging from 42.78% (Kolkata), 39.01% (Chennai) and 37.2% (Greater Mumbai). This is followed by transport sector -19.50%(Chennai), 17.41% (Greater Mumbai), 13.3% Kolkata

Figure 11:   CO2 eq. emissions per GDP versus GDP per capita for all the cities

Figure 12: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Delhi

Figure 13: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Greater Mumbai

Figure 14: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Kolkata

Figure 15: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Chennai in 2009-10

Figure 16 and 17 illustrates the sector-wise carbon emissions for IT (Information Technology) giants of India – Bangalore and Hyderabad. Due to lack of appropriate public transport system in these Cities and haphazard growth due to unplanned urbanisation has led to large scale usage of private vehicles. Emissions from transport sector ranges from 43.83% (Greater Bangalore) and 56.86% (Hyderabad). Figure 18 depicts the GHG footprint of Ahmedabad city with sector share ranging from 27.88% (Domestic), 24.92% (transportation), 22.41% (industry). etc.

Figure 16: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Greater Bangalore

Figure 17: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Hyderabad

Figure 18: GHG footprint (Carbon dioxide equivalent emissions, Gg) of Ahmedabad