Through local
partnerships

With broad experience and attention to the best technologies available, we create sustainable solutions through partnerships with local farmers for fuel supply.

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Tp biogas Technology of an agricultural biogas plant

Biogas production process

By collecting the organic residues into a closed reactor and adding the correct microbes, the natural process will start. Depending on the substrate the retention time in the reactor will vary. Food waste will only require a few days while grass material will require some more days. To give an example: straw from cereal production will need up to 90 days for complete breakdown of the digestible parts. Still the lignin will remain since – it does not break down at all in the biogas process. There are pre-treatment methods that will reduce the retention time to some extent. Wood is almost unbreakable by the biogas microbes. When all the food is eaten there will remain indigestible organic compounds, ammonia, potassium, phosphorus, and trace elements will remain. This material is called the digestate and is an excellent fertilizer. The indigestible organic material will add to the humus of the field and will prevent carbon depletion of the soil, which often is the result of using only chemical fertilizer.

Biogas illu

The direct use of biogas

Biogas is mostly used for direct energy production by feeding it to a gas engine which is connected to an electricity generator. For this, impurities like hydrogen sulphide and siloxanes need to be removed because they are harmful to the engine. No other upgrading is needed. In developing countries biogas is used as such for cooking or transport.

Tp biogas modern biogas factory

Upgraded biogas

In advanced use of biogas, it needs to be upgraded which means it needs to be treated. The first step is the separation of minor impurities. The main components of the biogas are methane and carbon dioxide. The carbon dioxide is an inert gas that cannot be used to produce heat or power. The second step is to remove the carbon dioxide, when biomethane is produced. There are several processes available with varying performance. At the lower end are technologies that produce grid gas quality with a minimum of 97 % methane purity. This is good enough to feed a gas grid or use as compressed biogas (CBG) equivalent to compressed natural gas (CNG). If the biomethane is destined for liquefaction it needs to be over 99 % pure. This is when it no longer causes problems in the cooling process. Liquefied Biomethane Gas (LBG) is equivalent to liquefied natural gas (LNG).

Use of biomethane

It is difficult to totally electrify the transport sector. The market for cars, buses, trucks and ships is currently developing towards more sustainable use of energy. Biomethane can be used where natural gas is already used today (CNG), as it is the same molecule. Biomethane can also replace the use of natural gas in the production of hydrogen in ammonia production, as well as other hydrogen applications.

Tp biogas bus
Tp biogas greenhouse

Use of Carbon Dioxide

The other main component of the biogas, Carbon Dioxide can also be utilised. Mostly the carbon dioxide is weathered to the atmosphere at the upgrading. This is waste because the carbon dioxide, when removed from the biogas, is in a concentrated form and only needs compression. Carbon dioxide capture from incineration plants is much more challenging and expensive since the CO2 is diluted with nitrogen gas from the atmosphere. Biogenic carbon dioxide can be used in beverages, in greenhouses, in vegetable growing and in all other applications where carbon dioxide is needed.

Design & development by lemon.no