Disadvantages of gasification are; toxin formation, operational safety problems, energy demand, high sensitivity, and time consumption.
This article discusses the disadvantages of gasification, as follows;
1). Toxin Formation (as one of the Disadvantages of Gasification)
This includes greenhouse gases like methane and water vapor (steam), and toxic materials like particulate matter and carbon monoxide . Such effluents can have negative environmental impacts, especially if released in large quantity.
By reducing air quality, and contaminating water and soil, the products of gasification, in the absence of proper handling, can pose a threat to environmental sustainability, economic growth and public health.
The reason behind this is the chemical composition of biomass feedstock that are used as substrate in gasification. These materials are usually carbon sinks, and may function as carbon sources as they undergo thermal decomposition.
Additionally, the thermo-chemical reactions in gasification may produce toxic compounds from feedstock, alongside useful products like biofuel.
Although gasification is not a totally sustainable process, it produces less hazardous effluents than other processes like open combustion and incineration, which are known to yield significant amounts of furans and dioxins .
2). Operational Safety Problem
Gasification poses operational safety risks to workers in the gasification facility, as well as environmental and health risks to the general public.
These risks arise mainly from physicochemical factors affecting the gasification process. They are also linked to possible equipment faults and operational malfunctions.
For example, leakages in the gasifier and its connected conduits can result in major fire hazards .
Excess internal pressure of the system can cause either biofuel ignition and explosion or gas escape and external fire outbreak. Also, excessively-low pressure can allow air inflow and may lead to ignition and fire outbreak.
These safety issues can be addressed through regular and effective monitoring, as well as optimization of the gasification plant.
3). Energy Demand (as one of the Disadvantages of Gasification)
Gasification is an energy-intensive process because it requires large amounts of heat energy to convert feedstock completely into the desired end-products. This is the case for other waste-to-energy processes like pyrolysis, that require high temperature conditions to work effectively.
For gasification to be effective, temperature of the gasification agent(s) must generally be at least 700°C. Supplying and sustaining such amounts of heat energy throughout the process requires significant amounts of resources.
Aside the main gasification stage, other stages of the process are also energy-intensive. Examples of such include pre- and post-treatment.
Materials that undergo gasification must be supplied in a state that ensures efficient conversion, and the products of conversion must be treated to remove impurities, and extract the most important constituents. These cleaning and treatment measures all involve energy.
To achieve some degree of energy conservation, circular economic practices like recycling are often implemented in gasification. Heat energy can be recycled by using heated feedstock and product gases as gasifying agents to provide the temperature needed for further gasification of untreated materials. Energy efficiency can also be achieve through additional measures like cyclic usage of cooling fluids.
4). High Sensitivity
Another disadvantage of gasification is its high level of sensitivity.
Gasification can be described as a highly-sensitive process, because it is influenced by multiple physicochemical and biological factors.
These factors include the composition and physical state of feedstock, temperature and pressure of the system, and operational condition of the gasifier .
Minor unfavorable shifts in any of the influential parameters can affect the entire process adversely, in terms of its effectiveness, safety, and quality and products.
Due to its sensitivity, gasification can be demanding in terms of supervision, unlike other spontaneous processes like direct combustion.
5). Time Consumption (as one of the Disadvantages of Gasification)
Gasification is a time-consuming process, especially in as a result of multiple treatment stages.
Pretreatment and post-treatment all involve measures to remove unwanted constituents from feedstock or products of gasification. These measures make gasification more time-intensive, and add to the operational cost involved.
Disadvantages of gasification are;
1. Toxin Formation
2. Operational Safety Problem
3. Energy Demand
4. High Sensitivity
5. Time Consumption
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