Self-igniting biochar delays biocoke heating plans in Tornio

The start of biocoke burning at Tornion Voima’s new combined heat and power plant has been delayed while the risks posed by its easily self-igniting raw material are assessed further, Yle reports. The fuel was originally due to be used in October to produce district heating, electricity and steam for Tornio residents.

The plant is to use a small surplus of biocoke from Outokumpu’s steelworks in Tornio that is unsuitable for the factory’s own processes. Biocoke is made from biochar.

A fire broke out at the steelworks around the turn of October and November when a supplier’s sack of biochar ignited while stored in a factory hall, Outokumpu said. Biochar, like many other types of biomass, can heat up on its own. It may smoulder and catch fire if heat builds up faster than it can escape, raising the material to its ignition point.

Biocoke is produced by heating biomass without oxygen to make biochar, which is then processed and formed into briquettes. Its calorific value is slightly higher than that of other biofuels, and it usually stores well, said Aki Hakulinen, chief executive of Tornion Voima.

However, biocoke is rarely used for district heating because it is expensive and difficult to obtain. Tornion Voima also produces energy by burning peat and other biofuels, including wood chips, stump chips, pellets and briquettes.

Using biocoke is intended to reduce emissions. Outokumpu wants its own biocoke plant to lower the climate impact and fossil carbon dioxide emissions of steel production. The company uses biocoke to reduce chromium ore into ferrochrome, which is used to make steel. Biocoke is made from renewable material, unlike conventional coke, which is produced from coal.