Gas an a source of Energy
Updated: Sep 1, 2022
Natural gas is methane and methane is a hydrocarbon. It is the simplest form of Hydrocarbon and from the same family of compounds such as petrol, diesel and coal. Methane is made up of 1 carbon atom and 4 hydrogen atoms to create a molecule of methane…or CH4.
When we combine methane with oxygen (O2), and add heat a chemical reaction occurs where the carbon and hydrogen atoms are oxidised. This is better known as combustion and it releases heat, together with carbon dioxide (CO2) and water (H2O). These are the mains products of combustion.
Carbon dioxide is famously a greenhouse gas, and the reason we’re attempting to move away from natural gas as a fuel source.
Carbon dioxide is also acidic and when it is mixed with water creates a solution called carbonic acid. This is what we commonly call “condensate” and this is the liquid waste that we need to safely dispose of from your boiler. Usually this travels down a white plastic pipe and into a drain. The pipe has to be plastic as it will eventually corrode through copper due to the acidity.
In the environment carbon dioxide in the atmosphere contributes to acid rain and acidification of the oceans. The sea absorbs around 30% of the CO2 released in to the atmosphere.
If, however, there is an insufficient supply of oxygen during combustion solid carbon and carbon monoxide is produced due to incomplete combustion.
A healthy gas flame appears blue to the naked eye. The blue colour is a product of the heat produced (around 1950 c). A standard flame from a candle, match or camp fire looks orange or red. The orange light from these flames is produced by left over carbon, not converted to CO2. As such a yellow flame is a sign of incomplete combustion. Try putting a spoon in to the orange part of a candle flame and it will be covered in a thin layer of soot, or carbon. This carbon was originally part of the fuel, and was produced when there was not enough oxygen molecules with which to combine.
If you ever see a yellow flame from a cooker or boiler call a gas engineer straight away.
Gas boilers also create small amounts of carbon and carbon monoxide during combustion. While carrying out a boiler service an engineer checks the levels of CO and CO2 to ensure these are within tolerance. The main burner can collect carbon and this should be removed. Often a good deal of it ends up in the condensate trap, which should also be removed and emptied during a service.
Boilers are now being produced to burn 80/20% methane and hydrogen blends. Effectively reducing 20% of our domestic carbon emissions. Equivalent to around 20 million tonnes of CO2 per year.
Hydrogen has 2.5x the calorific value of natural gas. Back in the days when the UK converted from town gas to natural gas people noticed their cookers didn’t burn as hot as they did previously. That’s because, despite the creation of town gas being rather dirty (and ignoring the fact it was highly toxic) it contained much higher concentration of hydrogen gas.
Hydrogen gas production is notoriously tricky and energy intensive. Together with heat pumps, hydrogen will be part of the decarbonisation of the UK