How does the sulphur content in the fuel affect its total heating value?

The correct answer highlights that sulphur content in fuel contributes positively to its total heating value. Sulphur itself is a combustible element and can release energy when it burns, which can enhance the energy content of the fuel. However, while it may add to the heating value, it's essential to consider that the combustion of sulphur also results in the formation of sulphur dioxide, which can lead to environmental concerns.

It's important to note that while sulphur can contribute positively to heating value, this is often balanced against the detrimental effects it has on emissions and environmental impacts. Many power generation operations therefore aim to minimize sulphur content to reduce the formation of pollutants.

In summary, while sulphur increases the heating value when combusted, the long-term operational and environmental impacts of its emissions are why fuel standards and regulations often limit its permissible levels in fuel used for combustion in power plants or engines.