We all have heard that use of biomass – instead of coal – for heating or power generation is a sustainable option.
But use of biomass for heating/power generation also releases CO2.
So, how can biomass heating or power generation be categorised as a sustainable energy avenue? Why would experts then advocate use of biomass as a key driver for climate change mitigation?
Well, these are indeed interesting questions.
While using biomass to generate power (or heat) does release almost as much CO2 to the environment as does use of coal for same energy output, the reason why use of biomass is advocated in place of coal is simple: Biomass is CO2 neutral (zero), while coal is CO2 positive.
What do I mean by this?
When you burn a lump of coal (or a m3 of natural gas), you are essentially taking carbon that was buried deep inside the earth and releasing it to the atmosphere. So, you are adding a positive quantum of CO2 to the atmosphere.
However, consider what happens when you burn biomass. Sure, you release almost the same amount of CO2 as with coal, but…wait. When the biomass was growing, it would have absorbed CO2 for its growth (remember, plants take in CO2, sunlight and water to grow). This is to a large extent the CO2 it releases back to the atmosphere when it is burnt to generate power or heat.
Thus, the quantum of CO2 the biomass releases to the atmosphere (+X) had been earlier absorbed from the atmosphere (-X).
What do you get when you do the following: (X) + (-X)?