Utilisation

From Biogas to Biomethane

Biogas can be used to generate electricity and heat in suitable CHP units. This type of utilisation is, however, strongly location-dependent and does not tap all the advantages of this primary energy source. By upgrading biogas to biomethane, many other positive properties and uses can be developed.

What is Biomethane?

Commercially available natural gas contains a high percentage of methane with smaller amounts of nitrogen and carbon dioxide. Its calorific or energy value can vary depending on where it is sourced across the world. The upgrading of biogas produces biomethane, which can be fed into the natural gas grid as a natural gas substitute and used in the same way.

From Biogas to Biomethane

The biogas produced, also called raw gas, is first subjected to pre-treatment which removes impurities from the biogas input before it enters the compressor and separation membranes. It includes gas drying, activated carbon filter and pre-compression.

In the subsequent upgrading process, the
CO2 and other gases contained in the raw biogas are separated using membrane technology. The upgraded gas contains up to 99% methane and is now called biomethane or bio natural gas. The other separated gases such as CO2 and H2 can be utilised for further applications.

Chemically identical
to natural gas

In general, after biogas upgrading, biomethane can be used wherever natural gas is used. Both variants are chemically equivalent and differ only in their fossil or biogenic origin. Before feeding it into the natural gas grid, it may be necessary, in some jurisdictions, to adjust the calorific value (e.g. by adding propane) and to odorise the biomethane for safety reasons, because methane is ordourless.

The Process:

1. Biogas Production
As a biogas plant manufacturer with more than 20 years of experience and almost 1,000 operating plants worldwide, we offer a wide range of plant configurations made of standardized and high-quality components, tailored to the needs of our customers. Seamless spare parts supply, an extensive service network and technical updates ensure trouble-free operation over the entire plant lifetime.

4. Feed-in / Injection
The biomethane injection unit is connected between the biogas upgrading plant and the gas distribution grid. Its functions are the more than calibrated measurement of the biomethane, gas quality measurement, conditioning, odorization and pressure increase to the grid pressure.

2. Pre-Treatment
The biogas comes from the biogas plant as a mixture of CO2, methane and a small amount of other gases and is desulfurized in the pre-treatment stage with activated carbon, filtered and dried to protect downstream components from wear or damage. The pre-treated gas is then compressed to 16 bar and fed into the membrane stage. The pre-treatment unit is also developed and manufactured by agriKomp.

5. CO2 applications
The CO2 removed from the biogas can be captured and recovered by liquefaction. This CO2 can be used in many industries, for example air enrichment for greenhouses and in food and beverage production.

3. Upgrading / Purification
The pre-treated and compressed biogas enters a membrane separation process, yielding a methane rich product gas and a CO2 rich off-gas stream. The innovative 3-stage membrane configuration can produce a biomethane purity up to 99 %. The membrane separation stage and control system is housed in a single bespoke container.

AGRIPURE®
The plant system for upgrading