Upgrading Biogas to Biomethane: How does it work?

Biogas upgrading: How does it work? Watch the video!

What is biogas upgrading?

Biogas upgrading to biomethane, also known as biogas purification, is a very attractive alternative compared to using a combined heat and power (CHP) system that generates electricity and heat.

Dropping electricity prices and less demand for electricity and heat, cause CHP’s to be non-profitable and expensive. Biogas upgrading can turn your biogas plant into a profitable organization. But what exactly is biogas upgrading? What technology should you use? How can you benefit from it? And what are your advantages when using our Bright Biomethane system?

Bright Biomethane is a major supplier of biogas upgrading systems. We have created this animation video of our system to show you how biogas upgrading works and to give you a better understanding on why to use it.

If you still have questions after watching the video, the article below might provide you with the answers. Still have questions or would you like to receive more information? Do not hesitate to contact us!

What is biomethane?

To upgrade biogas to biomethane you need a biogas upgrading plant, also referred to as a biomethane plant, biogas upgrader or biogas purification plant. As the name suggests, the output of the process is biomethane. Biomethane, also known as Renewable Natural Gas (RNG), is a pipeline-quality product gas and is similar to natural gas. Biomethane is a CO₂neutral, clean fuel without particles, that provides a good alternative to fossil fuel. It can be injected into the natural gas grid or it can be compressed to CNG (compressed natural gas) to use as transport fuel.

The biggest difference between the renewable product gas biomethane and the versatile fossil fuel natural gas is that biomethane is produced from biomass and waste. Biomethane is produced by converting biomass and waste, such as manure, agricultural waste, unpacked expired food products and sludges, via anaerobic digestion into biogas. This biogas, mainly containing CH₄ (55%) and CO₂ (45%) is then upgraded or purified in a biogas upgrading system.

The biogas produced at the biogas plant is not pure biomethane (CH₄). During the digestion process many other chemical components are produced, such as carbon dioxide (40%-45% CO₂), air (1%), hydrogen sulfide (H2S), hydrogen, Volatile Organic Components (VOCs) and siloxanes.

Upgrading of the biogas to natural gas quality by membrane gas separation means that CO₂ and other undesired components are filtered out. That is where the Bright Biomethane biogas upgrading system comes into play.

Biogas upgrading technologies

There are many different biogas upgrading technologies available on the market. All with the same goal: to separate methane from carbon dioxide and other chemical components and to produce biomethane. Examples of technologies to purify biogas include amine scrubbing, pressure swing absorption, water scrubbing, organic physical scrubbing, cryogenic distillation and membrane separation.

Each technology has different properties, efficiency rates and can be used for different types of biogas. Bright Biomethane uses membrane technology for the biogas upgrading to achieve maximum performance and recovery of methane.

Biogas upgrading plant using membrane technology

Bright Biomethane systems are equipped with a 3-stage membrane system. The highly efficient membranes for the separation of methane from biogas ensure an efficiency of more than 99.5%. In a membrane purification system, the biogas first enters the pre-treatment system where moisture and contaminations, such as H₂S, are filtered out. After that, the gas is compressed to reach the required pressure before entering the membrane system.

The remaining gases after the pre-treatment include CH₄ and CO₂. The compressed gas mix flows through the 3-stage membrane system where the CO₂ and CH₄ are separated. This 3-step membrane arrangement assures high biomethane quality (according to specifications) with maximum CH₄ recovery of 99.5% and higher. In the after-treatment system, the produced biomethane is analyzed and checked if all specifications are fulfilled. Also, TetraHydroThiophen (THT) is added that gives the biomethane an odorant. After this step, the biomethane is injected into the national gas grid or stored as compressed natural gas (CNG).

Bright Biomethane fully understands their clients. For that reason, we developed optimal heat recovery (> 0,25 kWt/Nm³ biogas) by recovering the heat from the process. The system has the lowest electricity consumption (0,22 kWh/Nm³ biogas) and almost all of the electricity that is consumed can be recovered as heat, which means no electricity loss and covering the main energy consumption of the biogas facility.

More reasons why you can benefit from our biogas upgrading technology.

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Bright Biomethane - Membrane Biogas Upgrading System

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CO₂ Recovery: producing food grade CO₂

In addition to the production of biomethane, the Bright Biomethane systems may be used to recover and liquefy CO2 to create an extra source of revenue for the plant owner. What is CO₂ recovery and what is CO₂ liquefaction? The CO₂ that is filtered after entering the 3-stage membrane system can be recovered and liquefied. A CO₂ recovery system can be easily integrated with the standard 3 or 2 stage Bright Biomethane membrane biogas upgrading systems. In this CO₂ liquefaction system, the CO₂ is compressed, filtered and cooled to reach the required purity and liquid state.

The liquefaction plant can produce food grade CO₂, which can be used in the food and beverage industry and in greenhouses. It can also be used in the refrigeration sector and in slaughterhouses. A great advantage of the CO₂ liquefaction recovery system is that the methane slip is reduced to zero as any remaining CH₄ returns to the biogas upgrading plant.

Applications of Biomethane

The methane-rich product gas can be used for different purposes. Biomethane or RNG can be injected into the natural gas grid, through which it is delivered to your central heating system or to your gas stove. That means that the gas that will heat up your house and warm up your dinner could be produced from cow poop.

Another option is to use the gas as transport fuel (CNG) for natural gas vehicles (NGV). CNG is used more and more widely across the globe. According to CNG Europe there are 3776 CNG stations in 2018 in Europe alone. Therefore, transforming your biogas into compressed biomethane gas is a clean and prosperous solution.

Advantages of biogas upgrading by Bright Biomethane

Bright Biomethane can transform your biogas produced from dairy waste, agricultural waste, sludge from a waste water treatment plant (WWTP), municipal solid waste (MSW) and many other kinds of biomass feedstock into biomethane. Our systems are able to work with nearly all biogas plant types, such as communal sludge digesters, industrial waste digestion plants and agricultural biogas plant. Using our proven membrane technology, we achieve efficiency of >99.5%. Our biogas upgrading systems are a bright idea for the perfect biogas upgrading solution.