The energy from coal-fired power plants in the future may be partially derived from the combustion of biomass.
This is the hope of Siemens Energy, which has reported promising results from early stage trials combining the combustion of coal and biomass.
In the company’s pilot-scale tests conducted with US alternative energy firm PetroAlgae, it was shown the biomass/coal fuel mixture burned well and produced 20 per cent lower nitrogen oxide emissions than coal alone.
The tests were conducted in a scaled-down version of Siemens’ pulverized coal burner design and used plant-based micro-crops grown by PetroAlgae. For use in the burner, the biomass was dried and finely ground into a powder. The powder and coal dust were blown into the fuel injector separately and mixed only just before combustion.
Biomass is considered to be a climate-neutral fuel because the amount of carbon dioxide that plants release is equal to the amount that they previously withdrew from the atmosphere for their growth.
According to Siemens, micro-crops such as algae consume around twice their weight in CO2 while they are growing. Due to this high carbon content, they deliver a great deal of energy relative to their mass.
It was claimed that in the pilot-scale tests, up to 10 per cent of the total heating value was provided by the biomass in these tests.
Gerda Gottschick, a spokeswoman for Siemens Energy, told The Engineer that Siemens intends to conduct further tests of the burner with increased quantities of PetroAlgae’s biomass fuel in the near future.
As far as commercial aspirations for the technology, Gottschick said Siemens will be ready to talk about it in more detail by the end of 2011 following more intensive tests.