Advantages of biomass and other facts about this energy source.
Advantages of biomass as opposed to fossil fuels are many. However, before we go to discuss the biomass advantages its worth mentioning few important facts about biomass like what is biomass, how does biomass work, how to capture energy from biomass, what are the disadvantages of this energy source etc.
What is biomass– is biomass renewable?
Biomass is a naturally produced organic material from plants and animals (micro organisms). Biomass stores energy from sunlight by the process of photosynthesis. Some examples of biomass fuels are wood, crops, manure, animal and human wastes etc. Biomass, besides using in solid form, can be converted into gaseous form through gasification route. Biomass is considered a low cost renewable source of clean energy because the energy in it comes from the sun and also due to the fact that biomass can re-grow over a relatively short period of time. Biomass fuel had been a major source of energy prior to the discovery of fossil fuels like coal and petroleum. In the last two decades energy from biomass has become one of the most commonly used alternative energy, second only to hydro power and wind energy. Even though the role of biomass is presently diminished in the developed countries, because of various advantages of biomass it is still widely used in rural areas of developing countries for their energy needs in terms of cooking and limited industrial use. In many south Asian countries like India, Pakistan and Bangladesh biomass is the first preference in rural areas when it comes to production of heat for cooking purposes. With increase in population and rapid depletion of fossil fuel resources like oil and coal, the demand for energy from biomass is expected to increase further in the coming days in remote rural areas of developing countries where expansion of grid power is not economically viable.
Classifications of Biomass
Biomass is generally classified into two broad classes – Solid biomass and Powdery biomass.
Solid biomass: These are any type of branches, non-forestry weeds like stems of ipomoea, lantana etc and agricultural residues like coconut shell, cotton stock, mustard stalk, corncob etc;
Powdery biomass: Powdery biomass are available either naturally in a powdered form or may be crushed into a powder like sawdust, agricultural residues like rice husk, groundnut shell, coffee husk, sugarcane trash (or cane trash), or dry leaves and grass;
How does biomass work?
To describe ‘how does biomass work’ the process of Photosynthesis needs to be explained. Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms’ activities. Through the process of photosynthesis, chlorophyll, which is a green pigment found in almost all plants, captures the sun’s energy by converting carbon dioxide from the air and ground water into carbohydrates, a complex compound composed of carbon, hydrogen, and oxygen. When burnt, these carbohydrates turn back into carbon dioxide and water and release the energy they captured from the sun. Thus, biomass functions as a natural storage system of solar energy like batteries. As long as biomass is produced with minimal long-term effect on the resources including land’s capacity to re-grow biomass plants, this natural storage system would continue to be the source of energy for an indefinite period, which is one of the main advantages of biomass fuel. Worldwide photosynthetic activity on plants is estimated to store more than 15 times, as much energy as is annually consumed by all the nations in the world!
How does biomass work to produce heat and electricity?
The most common method to produce electricity and heat from biomass has been to burn it in a boiler. The most common types of boilers are hot water boilers and steam boilers. Burning biomass in conventional boilers has many ecological advantages over burning fossil fuels.Wood chips, residues and other types of biomass are used in the boilers, in the same way as fossil fuels like coal, natural gas and oil.
Advancement in recent years has shown that a process called ‘gasification’ is more efficient and cleaner way to produce combustible gases from biomass, which reduces emissions of various particulates from biomass combustion. In this technology, biomass fuel is burnt in a device called ‘Gasifier’ with a low level of oxygen supply to generate clean combustible gas. A biomass gasifier takes dry biomass, such as agriculture waste, and with restricted supply of oxygen and high temperatures it results in breaking down of matters and release of volatile gas called synthesis gas (syngas) or pyrolysis gas. The syngas produced through gasification is predominately carbon monoxide, hydrogen, and carbon dioxide. The gasification process also turns wet biomass, such as food waste and human and animal waste, into methane by a machine called ‘Anaerobic Digester’.
These gases produced by the process of gasification can have end use for thermal application or for power generation. Using this gas it is also possible to operate a diesel engine on dual fuel mode. The gas is fed into a modified diesel engine which runs on a mixture of gas and diesel, resulting in a saving up to 80% of the diesel consumption. The engine is connected to a generator that produces electricity. The waste heat from the engine can be used for drying, heating or boiling water, or for running air-conditioning or cold storage plants.
One of the main advantages of Biomass gasification is that it has a continuing role in providing access to electricity. An increasing number of companies in Asia and elsewhere are producing gasifiers for this purpose. At the existing cost of biomass fuel and normal financing conditions as applied to renewable energy power projects, the cost of energy generation from biomass gasification based power plants using diesel engines running in a dual fuel mode is always lower than that from normal diesel engines running on pure diesel oil. In an industrial plant where an existing diesel set is re-modelled for use with a biomass gasification plant the payback period in a typical case, can be as low as 1 to 3 years.
Advantages of biomass and its drawbacks
The discussion about the advantages of biomass would remain incomplete without mentioning few drawbacks of this energy source. The method of harnessing energy could be different for each type of biomass fuel sources. The biggest disadvantage of biomass is that direct burning of some of the biomass fuels like wood, dried cow dung cakes etc. may cause pollution as these generate a lot of smoke. It releases carbon during burning process which has environmental hazard that need to be kept within bounds. If not managed watchfully, production of biomass can be at untenable rates, ecosystems can be damaged, large amounts of water can be consumed, and net Green House Gas emissions may take place.
But we need to look into the issue in entirety to see if biomass can be a good alternative fuel to fossil fuels. Experts believe that there is a large variety of biomass resources that can be produced sustain-ably and with negligible harm. Therefore, putting into practice proper policy is essential for gaining full advantages of biomass and avoiding the associated risks. To promote use of biomass energy beneficially it would require policy to guide industries to harvest the right kinds of biomass resources and for use of appropriate biomass conversion technologies and applications. Creating awareness about the advantages of biomass energy in proper perspective will build public trust that biomass can be a sustainable and useful climate solution and a source of low cost clean energy. As with any energy source, there are few disadvantages also of using biomass in spite of many advantages of biomass over fossil fuels. The main advantages and disadvantages of biomass energy are given below:
Advantages of biomass
- Biomass fuels are renewable;
- Biomass is supposedly an inexhaustible fuel source;
- Biomass energy produces less carbon than fossil fuel energy;
- There is minimal environmental impact if direct burning of plant mass is avoided to produce energy (i.e. when pyrolysis , fermentation etc. are used instead);
- Alcohols and other fuels produced from biomass are efficient, viable, and relatively clean-burning;
- Reduce dependency on fossil fuels;
- Helps in employment generation in rural areas;
Disadvantages of biomass
- Bio-fuels are inefficient as compared to fossil fuels;
- Direct burning of forest biomass releases some particulate pollutants into the atmosphere;
- A great deal of land and water are needed for some biomass crops to produce;
- Biomass fuel production and converting it to other fuels is quite expensive;
Increased awareness about the major advantages of biomass and how does biomass work discussed in this article would go a long way to help in better understanding of this low cost relatively cleaner and environment friendly energy which is expected to be the best option for replacing fossil fuels as a source of heating for the rural population.
Days may not be far-off when biomass would be the most important fuel for the rural households as a source of heating particularly in their cooking and agriculture activities such as crop drying. Till date biomass fuel has been utilized so widely, that it accounts for almost 15% of the world’s total energy supply and as much as 35% of rural supply in developing countries mostly for cooking and heating. Despite the fact that a number of environmental groups are opposed to the large-scale use of forest biomass in energy production due to its major disadvantage of carbon emission during the burning process, biomass is considered one of the few potential viable alternative natural energy sources for replacing fossil fuels in the near future.