However, CO2 is the conclusion of clean combustion. There is no way to “clean up” CO2 as there is with CO, HC, and NOx. In fact, my old VW Beetle puts out way more HC and CO than the most modern yet fuel inefficient gasoline vehicle on the market. But it probably produces far less CO2!

How?

First, one must know how HC and CO are formed. HC is “hydrocarbon”. It *is* the fuel. HC simply is fuel that didn’t burn at all. CO is partially burned fuel. During combustion, O is processed with HC. Ideally, the Oxygen combines with the Hydrogen to make H2O. More Oxygen combines with the Carbon to make CO2.

But during combustion, sometimes, the process runs out of Oxygen, leaving CO, or Carbonmonoxide. This means that less CO2 was made. The same goes for HC. Sometimes, the process runs out of HC. Since combustion needs heat, fuel, and oxygen, combustion stops dead in its tracks leaving these emissions behind.

When this happens, CO2 production is reduced. Introduce enough Oxygen into the combustion process, and less of these CO and HC compounds are left behind, and you get more CO2 and H2O.

That’s what emissions control devices attempt to do. Whether is be the old AIR pump, or the catalytic converter, or even fuel injection to better regulate fuel to the combustion process. All of these devices attempt to add air to the process in some way and put it to work. In the case of the catalytic converter, it uses Oxygen to combine to HC and CO to form H2O and CO2. Keep in mind, my old VW doesn’t have any of these devices. Thus, it will produce less CO2, and more CO and HC.