I SEE more and more electric vehicles every year.
Probably a bad idea. (But see caveat 1 below.)
Whenever energy is transformed from one form to another, some of it is always lost as heat energy.
A classic case is the amount of energy lost in the food pyramid. From one trophic level to the next, at least 90% is lost as heat. For example, a plant (say a grass) contains 1000 calories. Only 100 calories can be used by the herbivore (say a deer) that eats the grass. Only 10 calories can be used by the carnivore (say a leopard) that eats the deer.
Lots of leopards and few deer results in malnutrition and starvation in the leopards. Their numbers consequently plummet. That’s why there are always fewer leopards than deer in stable ecosystems. Poor leopard, but at least it’s on top of the food pyramid.
This an important principle on energy transformation or conversion.
Let us take for another example, electric vehicles. If the electricity comes from a battery that in turn is charged by electricity from a coal powered turbine of an electric generator, or other fossil fuels, energy will inevitably be lost as heat.
Just to be clear, a fossil fuel is a flammable or combustible carbon compound or hydrocarbon-containing material formed naturally in the Earth’s crust from the buried remains of prehistoric organisms (animals, plants, or plankton). Subjected to enormous pressure and heat underground, much of the oxygen and some of the hydrogen in the buried organic compounds are driven off mostly as water and carbon dioxide, leaving carbon-rich, oxygen-deficient compounds, such as coal, petroleum, and natural gas.
These carbon compounds or hydrocarbon-containing materials are thus chemically reduced, and can now be subjected to oxidation (combustion).
Below is a simplified representation of the process that runs an electric vehicle.
Chemical energy in coal (or other fossils fuels such natural gas or oil) → heat energy released by combustion of the fossil fuel → mechanical energy of heated moving gas → mechanical energy of the turbine of an electric generator → electricity (electrical energy) → chemical energy of a battery → electricity (electrical energy) → mechanical energy that powers the wheels of an electric vehicle.
Each arrow above represents a transformation or conversion of energy that loses energy as heat. The efficiency is never 100%. In the physical sciences, power is the rate of transferring energy (or rate of doing work, energy and work having the same unit, the joule) which is energy divided by time, or how fast work is done.
In other words, efficiency is ratio of the amount of power, produced by a machine to the amount of power put into it. For example, the internal combustion engine of a car is usually only about 25% efficient. The rest of the energy (75%) is wasted mostly as heat.
There are many arrows above. Each arrow represents a process of energy transformation in which some energy is lost, mostly as heat. Such waste of energy! In general, the more processes involved (the more arrows in our representation), the more energy is wasted.
Now note the following (more traditional) process.
Chemical energy in fossil fuel → heat energy released by combustion of the gasoline in an internal combustion engine → mechanical energy of the heated moving gas → mechanical energy that powers the wheels of a vehicle
Less arrows. Less energy is wasted as heat.
It can be deduced from the above that electric vehicles waste more coal if coal is the original source of energy. (To be continued)/PN
