September 17, 2024
What is Biogas?
Biogas is a renewable energy source that is created by digesting organic waste such as food waste, expired food and vegetable waste. During this process, called anaerobic digestion, bacteria convert the organic material into biogas, a mixture of mainly methane (CH₄) and carbon dioxide (CO₂). Biogas is often still used for heat and electricity production.
What is the difference between biogas and green gas?
Although biogas is already a sustainable energy source, it often still contains too many by-products and does not have exactly the same energy value to serve directly as a natural gas substitute.
Green gas, on the other hand, is a high-quality energy source that consists almost exclusively of methane by creating the right composition. This makes it a direct replacement for natural gas and can be injected into the existing gas network.
The upgrading process
In order to turn biogas into green gas, the biogas must be upgraded. This is done by first removing the by-products, which increases the methane content. There are several methods to do this, but the most commonly used are:
• Membrane technology: Here, the biogas is passed through membranes under pressure. The pores in the membrane allow the methane molecules to pass through, while other molecules are retained.
• Absorption: In this method, the biogas is brought into contact with an absorbent that selectively absorbs by-products such as CO₂.
• Cryogenic separation: By cooling the biogas to a very low temperature, the different components can be separated based on their different boiling points.
Why upgrade?
Green gas has a higher energy density than biogas, which means that more energy can be generated per unit volume that is exactly equal to the national/regional gas network. This allows it to be injected directly into the gas network. By using it via the gas network as a commodity, it gets a higher quality application than when it’s used for locally generating electricity. Alternative methods of the latter include wind and solar energy.
By upgrading biogenic waste streams such as food waste to green gas, the chance of methane and other greenhouse gases being released into the atmosphere is reduced. Methane is a powerful greenhouse gas that is released during the rotting process of organic waste. By using these waste streams for green gas production, it is given a high-quality application (such as natural gas) and also reduces greenhouse gas emissions. This reduces the use of fossil natural gas, but also helps the climate from the source. In addition, our dependence on natural gas imports is also reduced.
Conclusion
Upgrading biogas to green gas is an important step in the transition to a sustainable energy and raw material supply. By purifying and enriching biogas, a high-quality commodity is created that can be used as a direct replacement for natural gas. This contributes to reducing dependence on fossil natural gas and reducing CO₂ emissions and emissions at the source