A large amount of agricultural wastes generated by crop cultivation, are promising sources of energy for processing, production and domestic use in rural regions. The readily available leftovers from agriculture are either used to a lesser extent or burned out in open areas to prepare fields to allow for the subsequent cultivation of crops.
On average, 1.5 tonnes of plant residue are created in the process of processing one ton of the primary product. Additionally, large quantities from secondary residues get created in agro-industries which process the farm products such as paddy sugarcane, coconut fruit and vegetables.
The residues of agricultural crops often come with a disposal fee related to their disposal. Thus, those who use “waste-to-energy” conversion processes for energy generation and heat as well as in certain instances for the production of transport fuel could have a great commercial and economic benefits. They are particularly useful in the context of rural community applications and are widely used in countries like Sweden, Denmark, Netherlands, USA, Canada, Austria and Finland.
The physical and energy properties that agricultural wastes have are vital aspects to consider when deciding on feedstock and should be understood so that they can be used to complement a processor and feedstock.
There are six general biomass processing techniques that are that are based in direct combustion (for energy), anaerobic digestion (for methane-rich biogas) fermentation (of sugars that are used to make alcohols) and the oil extraction (for biodiesel), pyrolysis (for biochar as well as gas and oils) (for power), and gasification (for carbon monoxide and hydrogen-rich syngas). These processes can then be followed by a variety of other treatment (stabilization dewatering, upgrading refining) according to the specific end products.
It is widely known that power plants made of baled agricultural residues can be efficient and economical energy generators. Remains like rice husks and Straws of Wheat Straw as well as maize Cobs have already been accumulated to the point that they are an easy resource of power, especially when it is utilized locally to generate the power and heat in a combination.
The selection of process technologies must be based on the structure and nature that the feedstock is made from, as well as the intended outputs of the project. It is apparent that gasification or direct combustion of biomass is a good option for situations where power and heat are required.
Anaerobic digestion and fermentation as well as oil extraction are appropriate for specific biomass wastes readily extracted sugars and oils or high water content. However the only thermal treatment of biomass through pyrolysis could be the basis for all three types of products.
A variety of thermal processing techniques for the treatment of agricultural wastes require biomass’s water content to be lower (<15 percent) to ensure proper operation. For these types of technologies, drying energy costs could result in a substantial reduction in efficiency.
The moisture content of a product is an great significance since it is one of the primary requirements for selecting an technologies for energy conversion. The technology of thermal conversion requires biomass fuels that have a low moisture content. Those that have a high moisture content are suitable for biological processes like fermentation or anaerobic digestion.
The amount of ash that biomass produces can influence the cost of handling and processing that are part of the total cost of conversion. In contrast its chemical makeup is an important aspect to be considered when designing an energy conversion device, because it can cause issues of fouling, slagging corrosion, sintering and fouling.
Author: Engr. Husnain Sultan
Passionate to spread awareness regarding current and future environmental crisis.An international consultant, advisor and trainer with expertise in waste management, biomass energy, waste-to-energy, environment protection and resource conservation.