In an earlier blog I wrote that, short term, the best way to contribute to the planet’s energy issues is by reducing our energy “consumption”. We saw also that road transportation claims about 20% of the total energy bill. In addition we know that a substantial amount (about 70%) of the energy liberated from the car fuel is wasted mainly in the form of heat to the environment. The power required to move the car is substantially. Let’s take as a quite familiar reference: an incandescent lamp of 100 Watts. Only a small fraction of the 100Watts is actually converted into light (ca 10%) the rest is converted into heat. From experience everybody has a sense of how much heat a 100W bulb generates. After a few minutes the bulb is very hot and you could burn your fingers when you touch it. To compare, cars have engines of say between 50 and 150 horse power (hp). In the table below I have converted the hp’s into kW:
50 hp = 36 kW
100 hp = 74 kW
150 hp = 110 kW
Thus a 50 hp car consumes 360 times as much energy as our light bulb! And a 150 hp car even more than 1000 times. It is therefore clear that if we could save only a little bit on this waste, that we are talking immediately about large amounts of energy savings.
On top of the heat waste, cars propelled by internal combustion engines produce per km also an amount of CO2. And we all know what the impact is of CO2 on the earth ecosystem. To give you some feeling: one liter of petrol produces 2400 grams of CO2. At room temperature and one atmosphere that is about 50 liters. A typical car will burn about one liter of petrol per 20 km. Therefore, reducing CO2 will then directly reduce the energy consumption.
The European Commission and governments have from that point of view put quite strict regulations in place for CO2 emissions of cars. These regulations have a two prong approach: tax reduction for the buyer of clean cars and penalties for the car producer if the car does not meet minimum emission criteria. The criteria for the car manufacturer are: an average CO2 emission in 2012 if less than 130 gr/km. The penalty to pay by the car manufacturer is 20 E/gr in 2012 but increasing to 95 E/gr in 2015. On the other hand car buyers can get an appreciable tax (up to 5000 Euro’s) cut when buying a new car that has a low CO2 emission rating.
Sensible measures I would say.
© Copyright 2009 John Schmitz
 Actually less than 20% of the energy from the fuel becomes available to deliver mechanical traction of the car! Other losses are fiction, idling, standby, accessories and AC.