Friday, August 01, 2008

Four Equations for Vehicular Emissions Inventory

A number of studies, in developed and developing countries, apportioning the sources of air pollution put the transport sector atop – both from direct exhaust and indirect road dust. Increasing number of vehicles on the road mean emissions will increase, air quality will only get worse; fuel use will go up, and instead of moving ahead, people will actually grind to a stop due to congestion, unless a series of actions are in place to not only control the traffic, but also improve the technology to control emissions.

For any decision to stand trial, it is important that it is based on some level of information and most of the developing country cities, lack the capacity to build a baseline. A variety of models are available in the market, with varying level of complexities, which allow cities to develop their inventory. Depending on the model, the data requirements could be intensive; only delaying the process of building a baseline. Figure (to the left) presents the common parameters used for vehicular emissions inventory development

A report explaining four ways to estimate emissions from vehicular activity in a city, using commonly available data with local authorities, is available for download @ Note that this is not being proposed as an alternative to existing models, nor to undermine the integrity of the established models.

The four methods are
1. Using number of vehicles and kilometers traveled
2. Fuel consumption by vehicular mode
3. Passenger trips by mode and passenger kilometers traveled
4. Particulate pollution source apportionment

Figure below illustrates the four equations.

Each of the equations has their advantages and disadvantages in estimating the emissions. Depending on the available data, user can choose to utilize the best.

(authors interpretation)

This exercise is meant to jump start the analytical process by highlighting types of data required and how an inventory could possibility be built. Readers can also access example toolkits (VAPIS 1.01) to play with these equations and better understand possible complications

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