It is better for the climate that we share cars rather than everyone buying their own car or driving alone. Sharing reduces CO2 emissions from cars. The exact number of how much CO2 car-sharing saves can be calculated in different ways and will be based on a number of assumptions.

Each Amovens user profile contains a number indicating how many kg of CO2 the user has saved by sharing cars. We find this number by calculating how much CO2 is saved when the user rents another user's car instead of buying their own, or when the user shares a ride with others instead of driving alone.

Our calculation method and assumptions can naturally be discussed. To facilitate discussion and collective progress in understanding how car-sharing positively impacts CO2 emissions, we describe below the details behind our calculation method.

CO2 Savings from ridesharing

By driving together instead of each driving their own car, we save CO2 emissions. Our CO2 calculation is based on the CO2 saved by several people driving in the same car instead of each driving their own car.

Logic of the calculation

• Passengers avoid driving their own car when they book a ride with cars that are already going the same way.
• Each passenger corresponds to a saved car on the given distance.
• A car emits a certain number of kg of CO2 per kilometer driven on average.
• If a trip is 100 km, 100 times the average number of kg of CO2 per kilometer driven is saved.
• The savings are distributed equally between the driver and passengers on their Amovens profiles.

Inputs used in the calculation

• CO2 emissions per kilometer

Assumptions

• Average fuel consumption of the car per km (liters): 0.065
• Average kg of CO2 per liter of fuel: 2.525
• Average kg of CO2 per km: 0.065 * 2.525 = 0.16

Average for petrol and diesel, which still make up nearly 100% of the total car fleet in Denmark.

If a ride is 100 km and 1 passenger rides along, 100 * 0.16 = 16 kg of CO2 is saved, and the driver and passenger each save 8 kg of CO2, which is added to the number on their Amovens profile.

If 2 passengers ride along on the same trip, the CO2 savings are 2 * 100 * 0.16 = 32 kg of CO2, and the 2 passengers and the driver each save 32 / 3 = 10.7 kg of CO2.

Sources

• Danmarks Statistik (2018). Motorparken – Bestand af personbiler 1. januar 2020
• Klimarådet (2018, p. 17). Hvor klimavenlige er elbiler sammenlignet med benzin- og dieselbiler?
• Zetland (2017). Hvorfor elbiler altid er grønne (og hvordan de kan blive endnu grønnere)
• De Danske Bilimportører (2020). 2020 blev det grønne vendepunkt for bilsalget
• De Økonomiske Råd (2018). Dokumentation af bilmodel
• Niras (2020, p. 18) based on Energistyrelsen (2016, p. 59). Energistatistik 2016