How does biogas produce electricity?

Biogas contains chemical energy in the form of methane. This chemical energy can be converted to mechanical energy through an engine or generator and finally into electricity. This article will explain more about the specifics of the electricity generation process through biogas.

Applications of biogas

Biogas is created during the natural (anaerobic) decomposition of organic waste materials. The CO2 that is released in the atmosphere during this decompositioning is equal to the amount of CO2 new plants and trees need for their growth. This means that netto there is no real increase in CO2. This is why biogas is regarded as a renewable (green) energy source. There are many applications for biogas plants, the most used applications of biogas are:

• Generating electricity;
• In combined heat and power (CHP) plants;
• As a sustainable source of energy for cooking;
• As a new way to manage the amount of waste in agriculture;
• As a clean renewable fuel for transport vehicles;
• Injection into natural gas pipelines.

Why do we need electricity from biogas?

The electricity prices are increasing rapidly, which creates a lot of problems for the modern household. From the end of 2021 till April 2022 the electricity prices have increased more than 50%. This means it is becoming more beneficial to make use of electricity produced by biogas.

There are currently multiple ways to generate renewable electricity, the most known forms of renewable sources are solar- and wind power. But these sources are relying heavily on weather conditions. Solar power is only generated during the day and wind power is generated intermittently. This is where biogas has the advantage. Because biogas is able to generate a constant flow of energy during the day and night.

Generating electricity from biogas

Biogas contains chemical energy in the form of methane. The electricity from biogas comes as a result of converting this chemical energy to mechanical energy and finally into electricity. This can be done by the use of 2 transducers:

1. A biogas engine:

The biogas engine is used to convert the chemical energy into mechanical energy.

The gas engine is connected to the outlet of the biogas source. The engine works in a similar manner to the engine of a car, since it is composed of pistons within. The engine burns the biogas which rotates a shaft. Thus far the chemical energy has been converted into mechanical energy.

2. A generator:

The generator converts the mechanical energy, from the biogas engine, into electricity.

The generator is connected to the biogas engine, in such a way that the generator is powered by the rotating shaft from the engine. The motion transferred to the generator, creates electricity with the help of magnetism. The created energy can be transferred to a chargeable battery or directly to a power distribution grid for consumption.

The usage of the created electricity can be both domestically or commercially, since it can be made on a small or very large scale. That is dependent on the size of the biogas tank. On average a cubic meter (m³) of biogas can produce 2 kWh of electricity. This means that a biogas tank which produces 100 m³ per hour can provide 1.752.000 kWh per year. This translates into electricity for ±450 households per year!