Biogas and renewable energy

Biogas producers and upgraders need to remove certain pollutants from gas streams to protect downstream machinery, occupational health and the environment, and to reduce odours. Biogas contains siloxanes, which are abrasive and can damage combined heat and power (CHP) engines or the membranes used to upgrade the gas into biomethane. Similarly, hydrogen sulfide (H₂S) in gas streams causes corrosion and the acidification of engine oil. It also carries occupational health risks, and can harm the environment, particularly through the formation of acid rain. Finally, H₂S, volatile organic compounds (VOCs), terpenes and ammonia must all be removed to avoid causing an odour nuisance for site workers and neighbours.

Activated carbon is a reliable and versatile technology to remove pollutants from biogas so it may be used directly to power machinery and equipment such as CHP engines. Often, two filters in series may be required: one containing regular activated carbon to remove siloxanes or VOCs; and a second containing impregnated carbon to adsorb H₂S. This set-up will protect equipment warranties, prolong the lifespan of the machines, and reduce maintenance costs. Our filters are plug-and-play technology, making them suitable for facilities with no on-site personnel. We manage all carbon waste sustainably ourselves, saving your company the hassle.

During the upgrading of biogas into biomethane, activated carbon is widely used as a pre-treatment or polishing step. Where membranes are used to separate biomethane from carbon dioxide in biogas, DESOTEC filters may be placed upstream to remove siloxanes. Scrubbers or bioscrubbers are also used for upgrading, but are ineffective at removing H₂S. DESOTEC filters filled with impregnated carbon may be placed downstream to polish the biomethane so it is suitable for injection into the national grid or conversion into liquefied natural gas (LNG) or compressed natural gas (CNG).

Activated carbon filtration enables biogas producers to comply with environmental laws to protect air quality and reduce odours, and meet the terms of warranties for equipment such as CHP machines and membranes.

DESOTEC has the expertise and the technology to help you stay on the right side of these regulations – especially useful if your main focus is agriculture, not biogas. In urgent situations, such as odour complaints, we can deliver and install our filters rapidly for immediate operation. Compliant carbon waste handling is also included in our service. It’s worth noting that regulations are getting stricter, making it crucial to have flexible, adaptable treatment technology in place to future-proof your business. 

When used in biogas and biomethane purification, carbon becomes saturated with a range of contaminants, including H₂S – but thanks to DESOTEC’s pioneering treatment facility, it can now be treated and recycled. 

Once saturated, activated carbon filters from your biogas site are exchanged by DESOTEC and transported to our dedicated treatment facility. Here, the sulfur and other contaminants are safely desorbed and destroyed through thermal treatment, and the carbon is reactivated for reuse. This is the first treatment facility in the world capable of reactivating sulfur-loaded carbon, producing a recycled activated carbon that is as high quality as virgin carbon. 

This innovative and circular approach conserves the world’s resources, cutting your carbon footprint as well as your costs. 

Activated carbon is a very versatile technology, so there are many ways to optimise set-ups – e.g. placing filters in series, using different carbon grades, or combining filters with complementary technology such as scrubbers. DESOTEC’s experts carry out testing, advise on set-up design, and offer ongoing support as part of our full-service solution. 

DESOTEC’s activated carbon filtration solutions have a low total cost of ownership (TCO), as Capex costs are minimal and maintenance and upgrading are included in our service. Our new PF5 facility further decreases the TCO: it cuts transport costs, as carbon is now made in the EU rather than shipped from Asia; and saves our clients the cost of carbon waste disposal, as carbon can now be reactivated and recycled.