Targeted use of biocoal has the greatest effect

Charred biomass in the form of biocoal can help to improve the soil quality and reduce greenhouse gas emissions when added to the soil. Unlike untreated organic material such as leaves or compost, biocoal remains largely in the soil. This is because the coal has a chemical structure that makes it hard for micro-organisms to break it down.

The carbon, of which the biocoal is made, is therefore not released as carbon dioxide into the atmosphere, but instead helps to increase the carbon content of the soil.

In his doctorate (PhD), Simon Weldon investigated to what extent biocoal can help to reduce nitrous oxide (N₂O) emissions while maintaining the mineral nitrogen content of soil and compost. He discovered among other things that biocoal that is produced at high temperatures contributes the most to reducing emissions.

He also discovered that the ability of fresh biocoal to store nitrogen is limited, something that may have significance for the production of biocoal-enriched fertiliser.

“There are a number of uncertainties associated with biocoal that make it difficult to generalise. This is because there are many biocoal combinations, soil types, and not least variations in the environment,” explains Weldon.

He is nevertheless clear that biocoal is a valuable supplement for the future bioeconomy.

“Biocoal clearly has the potential to reduce greenhouse gas emissions from both compost and soil. The coal also contributes to a better composting process if it is added to organic waste resources,” he says.

It is also important to be realistic about biocoal so that the technology that is used to produce the coal is more targeted. Moreover, the coal must be used correctly if we are to take advantage of its full potential.