As a natural product, natural gas has a variable composition. In the Netherlands, a distinction is made between high-calorific gas and Groningen gas (low-calorific gas due to its high nitrogen content).
Groningen gas is used mainly by domestic consumers and by SMEs, while large-scale industry makes use of high-calorific gas. For OCI Nitrogen, it is extremely important to purchase gas that is of the most consistent possible quality and that has the maximum methane content. If the gas contains more ethane (C2H6) and therefore less methane (CH4), more CO2 will be produced per ton of ammonia; the C:H ratio then changes from 1:4 to 1:3. The value of the gas is determined, however, by its calorific value, which has little to do with the amount of CO2 emitted.