Biomass cofiring refers to combustion of biomass along with coal in a thermal power plant to reduce the amount of carbon dioxide released. There are 3 types of biomass cofiring namely direct combustion, indirect combustion and parallel combustion. The biomass has to be treated before combining with coal in order to improve the boiler efficiency.
The cofiring of biomass with coal has the following environmental benefits:
1. Cofiring reduces the carbon dioxide emissions which is a major contributor to global warming.
2. Sulphur content in biomass is low and hence cofiring will reduce the emission of oxides of sulphur like sulphur dioxide that contributes to acid rain.
3. Some of the tests conducted on biomass cofiring showed a reduction of 30% in oxides of nitrogen.
4. Cofiring in coal plants would strongly increase biomass use.
Some of the other benefits are it reduces the dependency on fossil fuels and thereby increases the share of renewable energy.
Some of the challenges faced in cofiring process is
1. One of the technical challenges is the modification required in the burner, fuel handling and storage systems to accommodate the biomass.
2. Availability of biomass is a major constraint
3. Losses in boiler efficiency due to high moisture content in the biomass
4. Disposal of ash generated in the process is a hurdle.
5. Biomass supply market is still underdeveloped which restricts the widespread use in cofiring.