Number Crunching in Transport

Thursday, May 13, 2010

India Transport Emissions – 2007 – Quantifying emissions without reliable data

Sudhir Gota

You simply cannot generate reliable emission estimates without accurate data. In fact, I would not hesitate to claim that “Without reliable data, transport emissions forecasting is as good as “fortune telling””. You need to consider the numbers with a pinch of salt or many a times consider the estimates as only numbers!
The reason why I am coming up with such an argument is because yesterday India released its 2007 Green House Gas inventory. I think it has some big problems with the transport estimates. It claims that the “road transport sector emitted 123.55 million tons of CO2e, which is 87% of the total emissions from the transport sector. The transport sector emissions include all GHG emissions from road transport, railways, aviation and navigation. It suggests that “the total number of registered vehicles in the country has increased from 5.4 million in 1981 to 99.6 million in 2007. Two wheelers and cars constitute nearly 88% of the total vehicles at the national level”.
The problem with the total numbers of vehicles in India is that registered vehicles cannot be used for estimates as we don’t have active scrappage/renewal system. Not many people have an idea as to how to guess the number of vehicles on road. Even the activity information (vehicle travel/year in km) is not available on public domain and often people borrow the numbers from some isolated studies and from other countries or other researchers.
In order to highlight the data issues, following are some of the critical issues

1. Vehicles
a. No breakdown by mode type and engine technology (e.g. Euro 1 or Euro 2 compliant, etc.)
b. limited data on active vehicle fleet
c. No data on splitting small cars with big cars, MUV’s, LCV’s
d. Isolated surveys to determine age of the vehicles
2. Fuels
a. No fuel split available - gasoline, diesel, alternative fuel
3. Activity
a. No data on urban vs rural share of movement
b. Occupancy – how many people/load
c. Annual surveys and proper methodologies on vehicle-km travelled, passenger-km travelled, and tonnes-km rarely exist
d. Reasonable data on fuel consumption per km travelled on various transport modes. This issue is critical as quoted values from lab testing differs from actual on road values
4. Emission factors
a. lack of locally representative emission factors for existing vehicle fleet

Coming back on the India’s 2007 estimate of 123 million tons in 2007 for an activity information of 99 million vehicles is too low as seen from the below graphic. In fact the estimates of CO2 /vehicles is lesser (1.2) than what researchers have quantified for passenger transport (ratio of 1.5 for passenger vehicles. Including commercial vehicles in estimation would expand this figure to a range of 2 to 4).
Strangely, the same authors, in an earlier study had quantified 106 million tons in 2000 with 48 million vehicles. Then why is that the doubling of vehicle numbers not showing impact?
One thing that hits hard in the below graphic is the huge variation of CO2 and vehicles. It seems that researchers do not agree with each other … a classic case of elephant and the blind men !!

Sunday, May 2, 2010


Sudhir Gota

Quantifying emissions from Railways (including LRT/MRT) is really tricky. Some of the variables which often trouble analysts are – use of construction, technology and occupancy factors which can make or break an analysis. Last year, Mikhail Chester brought forward a very interesting analysis on complete carbon footprint of transport modes and this study was critically accepted. The study provided a comprehensive environmental life-cycle assessment of not only vehicle and fuel components but also infrastructure components for automobiles, buses, commuter rail systems and aircraft. Many processes were included for vehicles (manufacturing, active operation, inactive operation, maintenance, insurance), infrastructure (construction, operation, maintenance, parking, insurance), and fuels (production, distribution). The vehicles inventoried in the study were sedans, pickups, SUVs, urban diesel buses, light rail, heavy rail and aircraft.

The important argument made by Chester was that one needs to closely look at the occupancy of Rails and its built infrastructure which often tip the scales. But, more often researchers think that one can always borrow the emission factors from different sources and this would provide some estimates of reasonable accuracy. This is a myth.

In order to demolish the argument of usage of common emission factor, we summarize many of the emission factors [1]available online. The data collation was further helped by inputs from ADB-TA - Reducing Carbon Emissions from Transport Projects.

It is to be noted that emission factors have been quantified using different methodologies with different boundaries. What sets them apart is the huge variation. The variation is between 16 to 1200 g/pkm. The Asian MRT’s which have very high occupancy ratios have values between 20 to 110 g/pkm. Segregating heavy rails, MRT and LRT may help in refining this further. However, it is to be noted that emission factors cannot be constant but dynamic with time in order to reflect changes in design, occupancy and other factors.

Thus, one cannot borrow the emission factor straight away. What one should do is to measure the fuel/electricity consumption to derive emissions. There is no easy way out.

[1] Please send us a request in case you would like to access the sources.

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