At this point in the series, I would like to bring attention to why hydrocarbons are so important to the energy industry. To be blunt, hydrocarbons have large quantities of energy. The energy is called the heat of combustion.
A combustion reaction, in simple terms, is hydrocarbon + oxygen equals water + carbon dioxide + heat (heat of combustion). This is what happens in an engine – air is brought in, it is mixed with gasoline, the mixture is ignited by a spark plug, the heat of combustion is turned into work by moving a piston, the carbon dioxide and water leave the system as exhaust. This type of engine is known as the internal combustion engine.
The problem is that this technology is old. In the 1800s, when the oil industry is starting to grow, a liquid fuel is of a type that has good physical characteristics: it is easily transported, dispensed; and although volatile, still manageable. Billions, perhaps trillions, of dollars are at stake in this technology today; but, global warming is forcing the world to reevaluate the future of the internal combustion engine.
Here is a table of the heat of combustion for various hydrocarbons:
|Fuel||Δ H (MJ/kg)||Δ H (BTU/lb)|
As can be seen from the Table, the chemicals with the highest heats of combustion are hydrogen and methane. This is a good thing. The problem is that gasoline and diesel have a lower heat of combustion value on a pound per pound basis. Notice that as you add carbons to the fuel, the heat of combustion drops. That means that you are getting less and less energy for a larger and larger carbon footprint.
This way of doing business is “unsustainable”, to use an industry cliche. Hydrogen and methane, as well as wind and solar, are definitely the path forward. The world cannot support carbon being blown into the atmosphere like this. In the next and last part of this series, I will explore some alternatives. Stay tuned in.