CO2-emissions of vehicles

On average every car in Belgium covers around 15,000 kilometres (source: FPS Mobility and Transport). That corresponds to an annual CO2-emission of approximately 2.8 tonnes. In addition we naturally use a lot of other vehicles. The impact of our method of transport on the total CO2-emissions cannot be underestimated and is approximately 20 to 25% (the precise percentage may or may not depend on international aviation and shipping).

The figures above only state the direct CO2 emissions ('tank to wheel' or TTW) through combustion. Indirect ('well to tank' or WTT), more specifically in the fuel production process, also consumes a large amount of energy. So at that time CO2 is also released. Different sources indicate the size of these, namely around 10 to 30% of the direct energy consumption.
Although the total of both sources of emission (WTT+TTW = WTW, or 'well to wheel') is actually the most accurate measure of the CO2 emissions of various vehicles, we have still used the TTW-figures above. For that reason the majority of figures can be found, e.g. on the advertising of car dealers or in different international reports.

Our custom route planner calculates the saving in relation to CO2 emissions of a bus, tram and train compared to an average car.

We do not give any calculation for the CO2 savings for the proposed dial-a-bus route.
After all that saving greatly depends on the occupancy of the bus, which varies greatly from trip to trip. In this way big differences may result in the distance to be covered and the route that a dial-a-bus will cover during a trip.

We always use an average CO2 emissions of 70 g/km for a bus in our calculations. The routeplanner cannot know beforehand what type of bus will be used (standard bus, articulated bus, hybrid bus,…).

We take the CO2 emissions of an average car (127 g/km) and deduct the CO2 emissions of an average bus (70 g/km) from this. The number calculated is multiplied by the number of kilometres the passenger will travel by bus.

For instance if a passenger travels 12 km by bus, the calculation is as follows:

(127-70) x 12 = 684

So a passenger saves 684g CO2 by travelling their 12 km by bus instead of by car.

We take the CO2 emission of an average car (127 g/km) and deduct the CO2 emissions of an average tram (1 g/km). The number calculated is multiplied by the number of kilometres the passenger will travel by tram.

For instance if a passenger travels 21 km by tram, the calculation is as follows:

(127-1) x 21 = 2646

So a passenger saves 2.6kg CO2 by travelling their 21km by tram instead of by car.

We take the CO2 emission of an average car (127 g/km) and deduct the CO2 emissions of an average train (28 g/km). The number calculated is multiplied by the number of kilometres the passenger will travel by train.

For instance if a passenger travels 38km by train, the calculation is as follows:

(127-28) x 38 = 3762

So a passenger saves 3.7kg CO2 by travelling their 38km by train instead of by car.

The best known way to compensate emissions of the greenhouse gas CO2 is by planting trees. Trees need CO2 to grow. In this process (photosynthesis) they use the carbon to grow: they capture the carbon (C) in Carbon-dioxide (CO2) in their biomass (wood, plant fibre, roots, ...). As a waste product they again emit oxygen (O2).
In that way trees (and plants) actually purify the air for humans. We actually do the opposite: we breath in air, use the oxygen O2 in it and breathe out more CO2. Daily we breathe about 900 grammes of CO2 per adult per year.
There are also lots of figures about how much CO2 a tree needs exactly to grow. From different sources (e.g. VBV, K.U.Leuven, UGent, …) we have selected the following information:

• 1 hectare of woodland (in our climate) absorbs around 10 tonnes of CO2 on average per year or around 27.5 kg/day
• Per hectare of woodland there are about 300 to 500 trees
• 1 fully-grown Flemish tree will absorb on average around 65 grammes CO2 (or 24 kg per year per tree)
• 1 kilometre by car will take about 2 trees to neutralise the emissions - that is about half of that for 1 kilometre by bus