ponpokku (27-03-2011, 10:29 AM) wrote:
Not exercising will cost more to the economy and the pocket.
Anyhow, here goes my calc (all figs converted to SI unit of Joules(J) for comparison):
- Calories to Joules [wiki]: 4.1840 J = 1 calorie
Energy density [wiki]:
- Petrol (MJ/L) = 34.2MJ/L
Human (70kg): Cycling, 30km/h for 1 hr (kCal) [ProHealth]= 840kCal/hr.
Human (70kg): Cycling, energy expanded per km (J)= [(840 / 30 ) X 4.1840] = 117.152kJ/km.
Car: Petrol consumption per km (50% highway, 50% urban) (Latest test) [Oneshift.com] (extremes of results amongst 8 cars listed) :
- Toyota Altezza RS200 6MT: 8.8km/L
- Daihatsu Sirion 1.3 (A): 13.6km/L
Average: 11.2km/L between the 2 models.
Car (Average sedan): Energy expanded to travel 1 km (in Joules)= [34.2MJ/L / 11.2km/L] = 3.0536MJ/km = 3053.6kJ/km.
Suppose the driver is the only occupant in the car, traveling by car requires = [3053.6 / 117.152] = 26.065X the amount of energy expanded as compared to traveling on bicycle.
Please note that car transport mode might be underestimated as it only considers energy based solely on petrol consumption, it does not include energy expanded by the driver in driving NOR other energy expanded in petrol exploration, refining nor transport NOR energy expanded to construct/ maintain the car which is more complex then a bicycle.
On a per capita energy consumption in 'transport by car' basis, energy efficiency be improved if more than 1 passenger(s) are conveyed. However, given the >25X excess energy usage by car transport over bicycle transport, car transport cannot match bicycle transport in terms of energy efficiency.
Cause of energy inefficiency in car transport:
- Most cars have a kerb weight in excess of 1 ton, way heavier than its maximum cargo load- thus the inefficiency.
- "Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18%-20%." [wiki: 'Internal combustion engine']
Whenever I see an adult on a bicycle, I have hope for the human race. ~ H.G. Wells