Biomass-based electricity is gaining attention of regulators and policy makers, as the country moves towards power generation that is not carbon-intensive.
The Union Ministry of New and Renewable Energy (MNRE) announced central finance assistance for projects utilising biomass like bagasse, agro-based industrial residue, crop residues, wood produced through energy plantations, weeds as well as wood waste produced in industrial operations for power generation.
According to Union Power Ministry, Around 2.6 per cent of the country’s electricity demand is met by biomass.
About new Technology:
Use of biomass to fire steam boilers at electricity generation units is also increasing to produce cleaner power.
But these boilers are designed only for specific types of agro residue such as paddy husk, paddy straw, mustard, among others to be fired for its lifetime.
A vibrating grate boiler launched recently in Denmark can be a solution for firing any kind of biomass. These boilers have a capacity of 75 tonnes per hour.
The new Denmark-based technology allows the plant to fire a wide range of fuels with less fuel preparation and handling, and mainly avoid the energy-intensive process of briquetting and pelletisation.
The new Denmark-combustion technology is advantageous because of the vibrating grate.
The grate of a steam boiler supports the solid fuel in the furnace.
It is so designed that it can also allow air to admit air in the solid fuel for combustion.
Vibrating grate is different from the more common stationary, travelling and reciprocating grates since it accommodates biomass of every density.
The moisture content of the fuel, however, has to be 15-20 per cent.
Since the vibrating grate supports firing agro residue of any size, it saves energy consumed for processing biomass for energy generation
How it works?
Instead of converting biomass into pellets or briquettes, the agro residue is converted into bales right after procurement from the farmers.
Before it is conveyed to the combustion system, it is subjected to a bale string cutter and dosing screw to cut the string tying the bales and mixing the bales to reduce its size respectively.
The size of the bale is reduced for achieving complete combustion of the biomass fed into the boiler.
Then, the bales are sent to a vibrating grate for combustion.
Here, the combustion happens as a series of events.
For the first 250 seconds, a set of fuel is fired, and then it is moved to the next combustion stage by vibration.
After the first set of biomass is moved to the next grate, fresh biomass enters the firing system for combustion.
After complete combustion, the burnt biomass in the form of ash is let out for disposal.
The biomass-based boiler is as efficient as a coal-based boiler.
The average steam to fuel ratio of this biomass-fired boiler is 4-4.5 and the efficiency is also achieved upto 85 per cent, which is equivalent to coal-based thermal power generation.