The conversion of biogas into biomethane is known as biogas upgrading. Carbon dioxide, sulfide, hydrogen sulfide, water, and other pollutants are removed from biogas during its conversion to biomethane. Biomethane has multiple potential applications, including injecting it into the natural gas system or fueling vehicles.
What occurs during biogas upgrading?
While there are many ways to improve biogas, the four most common include amine gas treatment, pressure swing adsorption, selexol absorption, and water washing.
- Pressure Swing Adsorption
This method uses an adsorbent material and pressure ranging from 4 to 10 bar to retain the carbon dioxide. A solid with a large surface area and pores work as an adsorbent. As a result of the carbon dioxide absorbed by the porous material, the result is biomethane. The adsorbent material can absorb a certain amount of carbon dioxide before it needs replacement. Therefore, there’s a need for regular monitoring and replacement. The pressure swing adsorption method uses materials like zeolite, alumina, activated carbon, resin, and silica gel to separate carbon dioxide from biogas.
- Amine Gas Treating
The term “amine gas treatment” describes using different amines to remove hydrogen sulfide and carbon dioxide from gas. The methane in the biogas is separated from the hydrogen sulfide and carbon dioxide by combining them with the amine gas. The lighter methane is collected at the top of the chamber, and the heavier mixture of hydrogen sulfide, CO2, and amine is collected in the bottom part.
Water Washing
In order to purify biogas and produce biomethane, water washing absorbs carbon dioxide from fuel using high-pressure water. Pressurized water dissolves any hydrogen sulfide and CO2 in the gas. The methane goes straight through the system rather than being absorbed by water. One efficient method of converting biogas to biomethane is water washing. This can reach methane rates of up to 98 percent.
- Selexol Absorption
The Selexol absorption technique removes methane using polyethylene glycol while absorbing hydrogen sulfide and CO2. Using polyethylene glycol, this method is equivalent to water washing. Compared to water, Selexol is a better absorber of hydrogen sulfide and carbon dioxide. This results in less pumping required for biogas purification. Furthermore, Selexol eliminates other impurities, such as hydrocarbons and water.
What is the result of biogas upgrading?
Biogas is converted into biomethane through biogas upgrading. Biomethane is chemically equal to subsurface natural gas and has a methane content of 90% or higher. Because it is highly versatile and can be used in place of natural gas for a wide variety of purposes, such as fueling cars, water heating, cooking, and power generation, this gas has numerous potential uses.
What are the advantages of biogas upgrading technology?
The use of membranes for biogas upgrading has several advantages that affect operational and budgetary aspects:
- Control and consistency
Controlling the gas output quality is important; the membrane makes it easy. With this technology, chemical imbalances aren’t a concern.
- Cost-effective
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- Sizes
Biogas upgraders that use membranes have a minimal impact on the environment.
- Simple and robust
There are only a few moving parts in membrane-based upgraders, so they’re dependable and easy to maintain. Because of this, servicing and maintenance expenses are kept low, and operating plant hassles are reduced. Also, more money is directly proportional to higher uptime. Again, operational expenses are reduced by extending the service life of the membranes through extensive pre-treatment.
Can we liquefy biogas?
The conversion of biogas into liquid form, known as liquid biogas, offers great promise as a transportation biofuel. Liquid biomethane’s advantages over fossil fuels include its carbon neutrality, widespread production, and renewable resources.
Time taken to produce biogas
Biogas production takes different amounts of time. Biogas plants can employ an anaerobic digestion project to accelerate decomposition artificially, making them more suitable for use as fuel. Under less regulated conditions, this procedure can take up to one month to finish. One example is the significantly longer time it can take to produce biogas from a landfill.
This is due to the fact that creating an oxygen-free atmosphere in a landfill is more challenging. Methane generation can only occur if aerobic bacteria consume all the oxygen in the waste. Once this process finishes, methane production can begin. It usually takes around 12 months. The surrounding environment impacts the deoxygenation rate and the time it takes to produce methane since landfills are usually outdoors. The process will be slowed down in dry and cold regions, while its acceleration will occur in humid and warm conditions.
Conclusion
By confirming the biogas upgrading process’s purity and optimizing the energy produced, biogas analyzers and monitoring systems increase the ROI of biogas upgrading. Additionally, they aid in reducing flaring and the leaking of greenhouse gases.