As of 2014, there were some 1.24 billion highway vehicles worldwide, not including construction equipment, farm tractors, locomotives, motorbikes, or aircraft.
In operation the engines produce both a hot exhaust, and cooling system heat, which in turn, is discharged into ambient air.
Let’s make a very simple calculation, using 112 488 BTU per gallon of gasoline — we will exclude diesel for now.
The average efficiency of an internal combustion engine is around 28 per cent; that is 28 per cent of the fuels energy is actually used to turn the wheels; the other 62 per cent is given off as waste heat.
Doing the numbers and assuming an average combined run time of four hours at a mean consumption of two gallons per hour (commercial vehicles would be closer to 14 hours at seven gallons per hour, versus a personal average commute of one to two hours at two gallon, or so, per hour). Each vehicle would produce, on this time frame, an average 566 940 BTU.
Worldwide this comes to a total heat output for the worlds highway fleet of a staggering 7.03 X 1014BTU, (703 000 000 000 000 BTU) per four hours of operation. Remember, one BTU is the amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit.
These 703 trillion units would raise the temperature of 7.03 trillion pounds of water one degree every four hours of vehicle operation.
It’s important to note that residential and commercial heating losses, hydrocarbon fired and nuclear electrical plants, industrial processes, locomotives, ships, commercial and agricultural equipment, commercial and private aircraft, rockets delivering satellites, etc. also make significant contributions to thermal pollution, none which have been accounted for in this calculation.
This was just a modest calculation to illustrate a large problem. Remember when “Mom” told you to “close the door, stop trying to warm it up outside!!” Well we are giving it a go with the burning of fossil fuels. A Swedish study in 2003 at the Lulea° University of Technology calculated that in 1880 the net outflow of heat from our planet was equal to the geothermal heat flow.
At the time of their study they found “net heating” from the burning of hydrocarbon, in Sweden, to be three times the geothermal heat flow.
The “bear in the igloo,” in the case of the global warming issue, the one rarely mentioned, is attributable to the size of the human tribe.
The world’s population has reached 7.46 billion in numbers, and as such, requires huge inputs of energy for everything we now consider essential. Our consumption is having a huge detrimental effect on our “nest.”
In general, electrical motors have an efficiency of 60 per cent, new technology, i.e. VFD controlled electrical motors, even higher. If civilization transitions to electrical vehicles an obvious reduction in thermal pollution would be achieved, simply by removing the heat of combustion.
Trouble is, electric vehicles are not widely available, and as of yet, none for hauling cargo. Transition will take time.
Lorne Oja is an energy consultant, power engineer and a partner in a company that installs solar panels, wind turbines and energy control products in Central Alberta.