Fixed Dome-Type Biogas Plant: A Sustainable Solution for Clean Energy and Waste Management in India

The fixed dome-type biogas plant is a simple and popular way to produce biogas, especially in villages or small communities. It has a dome-shaped cover built underground to store the gas safely. This plant is easy to use, lasts a long time, and is affordable, making it great for families, farms, and villages. Organic waste, like food scraps or animal dung, is put inside, and after a few weeks, it produces biogas.

Fixed dome-type biogas plant isn’t just about making energy—it also helps manage waste. Instead of letting waste rot and cause pollution, it turns it into biogas, which can replace fuels like wood or coal. This reduces smoke and keeps the air clean. The leftover material from the plant is a great fertilizer that helps farmers grow healthy crops.

The fixed dome-type biogas plant is a smart and eco-friendly way to turn waste into valuable energy. It’s a small solution that makes a big difference for people and the planet!

Before we discuss the fixed dome-type biogas plant in detail, we need to know the anatomy of the biogas briefly. Biogas is a type of gas made when organic materials like food scraps or animal waste break down naturally without oxygen as long as there is some moisture. This process produces biogas, primarily methane (about 55-65%) and carbon dioxide (about 30-40%). It also contains tiny amounts of other gases like hydrogen, hydrogen sulfide, and nitrogen.

Biogas is very useful because it can be burned to produce energy. Its energy value is similar to natural gas, which can be used for cooking, heating, lighting, and even running engines. It can also be upgraded into synthetic natural gas (SNG) by removing carbon dioxide and hydrogen sulfide.

In a country like India, biogas production is essential because so many cattle farms provide the organic waste needed to make it. Many families in rural areas use small biogas plants, usually about 2-3 cubic meters in size, to produce gas for daily use. Biogas also generates electricity for farming and small industries in villages, helping reduce the need for costly fuels.

Design option of biogas plant:

There are three main types of biogas plants: flexi plants, fixed-dome plants, and floating-drum plants. In this article, we’ll discuss fixed dome-type biogas plants primarily used in India.

A fixed dome-type biogas plant has a sealed digester with gas stored in the top part. This gas space doesn’t move, so the structure stays strong and stable. When biogas starts forming, the waste mixture, called slurry, moves into the outlet tank. The more gas stored, the higher the pressure inside the digester.

There are two main types of fixed-dome biogas plants: the Deenbandhu type and the Janata type. Both are designed to make biogas production easy and efficient for different needs.

Deenbandhu model of fixed dome-type biogas plant:

In 1984, AFPRO (Action for Food Production) in New Delhi created the Deenbandhu biogas plant. “Deenbandhu” means “friend of the poor,” the plant was designed to be affordable while still working efficiently. To lower the cost, the plant’s design reduces its surface area without affecting how well it produces biogas. It looks like two spherical sections joined together, and this unique shape works as the digester, fermentation, and gas storage chamber.

The Deenbandhu plant is built using strong materials like bricks and concrete, which last a long time. Its spherical shape keeps the structure strong because it stays under compression, meaning the pressure from inside doesn’t damage it. The digester is connected to an inlet pipe, where waste enters, and an outlet tank, where leftover slurry exits. The top part of the outlet tank holds the slurry that gets pushed out when biogas is produced.

This biogas plant can handle a capacity of about six cubic meters per day. It has several advantages: it costs less to build, has no moving parts, doesn’t use steel that can rust, lasts a long time, and is built underground, saving space and staying warm even in winter. Plus, constructing these plants creates jobs for local workers.

The fixed dome-type biogas plant is helpful, but it does have some problems. Sometimes, small cracks or holes can form in the structure, which lets the gas leak out and makes the plant less effective. Also, the gas pressure can change a lot, and if the digester gets too cold, it won’t work as well to produce biogas. This type of plant works best in places where experienced biogas technicians can guide its construction and maintenance.

Overall, the Deenbandhu biogas plant is a great way to turn waste into energy at a low cost while supporting local communities!

PAU Janta model of the fixed dome-type biogas plant:

The Punjab Agricultural University in Ludhiana has created a big fixed dome biogas plant that is easy to build and use. This design has been approved by ICAR (Indian Council of Agricultural Research) and is recommended for farmers and other users. The Ministry of New and Renewable Energy (MNRE), Government of India, also supports this design so that more people can use it to produce biogas and electricity.
This biogas plant is made entirely of bricks, making it strong and long-lasting. It works well in all parts of the country. It can be built in different sizes, from small ones producing 20 cubic meters of gas per day to large ones producing 500 cubic meters per day. This one is cheaper than floating drum biogas plants—about 60-70% of the cost—and needs less maintenance. The money spent on building it can be recovered in 3 to 4 years.
This design is especially useful for dairy and poultry farmers, gaushalas (cow shelters), schools, temples, villages, and small industries. It’s a great way to turn waste into clean energy while saving money!

Precautions for laying gas pipelines for fixed dome-type biogas plants

How do you install Biogas pipelines safely and adequately?

Installing a fixed dome-type biogas plant needs trained and skilled workers to ensure it works well and is safe to use. Here’s what you need to know about setting up the pipelines:

1. Choosing the Right Materials
   • Biogas pipelines should be made of high-quality steel or HDPE (a type of strong plastic). These materials are safe and durable, especially for indoor connections.
   • Steel pipes that go underground should be painted with protective coatings to prevent rust. However, HDPE pipes are often better because they last longer and work more efficiently.
2. How to Lay the Pipes
   • Pipes should be placed at least 30 cm (1 foot) below the ground for safety.
   • Only use bends (not sharp elbows) for 90-degree turns. Bends help the gas flow better without losing pressure.
   • Keep the pipes at a slight slope to help remove any water that collects in the pipes. Underground pipes should slope at 1 cm per meter, and overground pipes should be fixed along walls with clamps every 2 meters. Make sure the pipes don’t sag anywhere.
3. Valves and Connections
   • Use high-quality valves like gate valves, plug valves, or ball valves to control the gas flow without losing pressure.
   • Connect burners to the gas pipeline using neoprene rubber tubes, as they are safe and durable.
4. Managing Water in the Pipes
   • Biogas contains water vapours, which can turn into droplets when the temperature drops. To fix this, install a water remover (called a drip trap) at the lowest point of the pipeline. This keeps water from blocking the flow of gas.
5. Safety in the House
   • Place the gas cock (the valve to turn the gas on and off) in a safe spot, out of reach of children.

By following these simple rules, the pipeline of fixed dome-type biogas plants will work smoothly, safely, and last long!

Conclusion

The fixed dome-type biogas plant is a smart and simple way to turn waste into useful energy. It helps people in small communities and villages by giving them clean energy and reducing waste. Even though it has some problems, like gas leaks or low temperatures, it is still a great choice for many families and farmers. The fixed dome-type biogas plant shows how we can solve problems like waste and pollution with creative ideas. With more people using this technology, the fixed dome-type biogas plant can help us live in a cleaner and greener world.