Biomass is a great source of renewable energy and is gathered from biological materials. This energy source can be used directly to get power of it can be converted in some other forms of energy like biofuel. This organic material stores sunlight in form of chemical energy and advantage of these products is that they are mostly wastes of other processes. Famous biofuel includes wood, straw, wood waste, manure and other byproducts gathered from farming, forestry or animal husbandry etc.
All these plant matters are used to generate electricity with help of steam turbines and direct combustion processes. Mostly two kinds of products are used to generate electricity, one biofuel and other forest residues.
Problem faced recently with use of biomass to generate electricity is emission of carbon in air which is contributing to global warming. Therefore some beneficial biomass resources are identified to reduce emission of heat-trapping gases, but it would be expensive and take longer to transform into clean form of energy. These resources includes
Energy crops: energy crops are good to grow in large quantities, but it is important to consider the food production is not reducing by growing them on marginal lands. Balanced cycling of carbon from air to plants and then soil can result in plant decay; therefore it is important to grow these kinds of crops now.
Grasses: before growing annual food crops, thin stemmed perennial grass use to cover the land and grow very quickly. If we start growing grass on land for few years, then we can harvest food crops there once again as well. This grass is beneficial for many things but it is also good to get Bioenergy.
Manure: from poultry and livestock management farms we can easily get manure to use it for purpose of generating energy through gasification. Although this process emits carbon in the air but we can control it can convert it into beneficial resource.
Woody biomass: Bark, sawdust and other byproducts of milling timber and making paper are currently the largest source of biomass-based heat and renewable electricity; commonly, lumber, pulp, and paper mills use them for both heat and power. Mill residues are also for generation of electricity through renewable resources.
Converting Biomass to Bioenergy:
From ancient times method of burning biofuel to make heat or other kind of energy is popularly used. Through this method steam power and electricity is generated but burning is not limited to one type only now days. Different processes took place for this purpose now.
Direct combustion: this is the oldest method to generate electricity from biomass. In this methods steam is produced to run turbines and generate electricity. The problem with direct combustion is that huge amount of energy get wasted and cause pollution.
Co-firing: one method that took height recently is burning the mix of biomass source with coal to generate electricity. This method is low cost and emits less harmful gases as well.
Repowering: under this process coal plants are converted into biomass sources to run solely on biomass.
Combine heat and power: process of direct combustion of biomass release heat which can be used to heat building of other industrial work. Here wasted heat is used with direct combustion system which is economical and environment friendly.
Gasification: heating biomass with controlled amount of oxygen under certain pressure to convert it into carbon monoxide is called syngas. This process is followed to remove contaminants like carbon from gas before converting heat into electricity.
Pros and cons of using biomass:
- This is renewable source of energy
- biomass is part of carbon cycle
- electricity generated through biomass is inexpensive as compared to coal or oil
- biomass is available all over that world
- extraction of biomass can be counted as an expensive factor
- biomass plants need huge areas to setup
- its crops are not available round the year