A comprehensive, reliable supply of renewable energy and the ability to produce regenerative fuels such as bio-LNG and bio-CNG are key to decarbonization and energy transition efforts. Whether it’s combined with a Kompogas® plant to create a complete solution or deployed on a standalone basis, BioMethan gas upgrading technology completes the range of HZI products enabling energy to be produced from any sort of waste or biomass – in this case employing an upgrading process to convert raw biogases into high-purity biomethane that can be used as a versatile energy source.
A by-product of the process is carbon dioxide, which can be used to generate additional revenues in the form of gaseous, liquefied or solid carbon dioxide deployed as an industrial product gas – for example in plant breeding, as an extinguishing agent or refrigerant, or as a raw material in the chemical industry.
HZI’s BioMethan technology thus makes a major, direct contribution to efforts to increase the use of renewable energy, phase out fossil fuels, and decarbonise the society in which we live.
Raw gases from a wide range of different sources are suitable for upgrading: the digestion of municipal green waste, organic household waste or agricultural biomass. Sewage and landfill gas can also be converted into energy. This extends a plant’s value chain and promotes the circular economy.
Depending on the composition, the raw gas pretreatment may be required. Then comes the main process, where the carbon dioxide in the stream of gas is separated from the methane, with the resulting biomethane conditioned to the desired quality parameters.
In consideration of the requirements and circumstances, HZI offers two separation processes: amine scrubbing and membrane technology. Both guarantee the highest quality and maximise the purity of the methane.
Biomethane is highly versatile. It can be used to generate heat and power, or as a compressed or liquefied biofuel. Given that it is natural gas quality, it can be transported and stored in the existing gas grid infrastructure. Unlike fossil fuels, biomethane is a sustainable energy source and can be produced on a calculable basis.
The technology’s modular container construction allows several units to be combined, enabling plants to be designed flexibly to upgrade gas volumes of between 100 m3 and 2000 m3/h or even greater.
In the first step of the process the raw gas is pretreated and compressed to operating pressure. After drying, heating and fine purification, the gas is fed into the membrane modules. The carbon dioxide is separated from the methane by selective gas permeation, with the CO2 passing through the surface of the membranes more quickly than the methane, which is retained in the membranes and removed from the modules as product gas.
This is a plug-and-play process technology requiring no additional operating resources such as water or heat.
Amine scrubbing is a chemical process that is suitable for sites with a source of heat and high product gas requirements, and where the gas has to be delivered from the gas upgrading unit to the feed-in station at low pressure. It is also no problem to increase the pressure for sites outside Germany where higher pressure is required.
After pretreatment, the raw gas flows through a packed column, where an amine solution that absorbs carbon dioxide is trickling from top to bottpom in the opposite direction to the gas. Then biomethane of up to 99.9% purity is removed at the top of the tower. The used amine scrubbing solution is regenerated for reuse in the process.
This process is highly robust when it comes to dealing with impurities in the stream of biogas, and like membrane technology stands out in terms of high plant availability.
Advanced Contaminant Removal
Depending on the composition of the waste or biomass, biogas may contain impurities, for example volatile organic compounds (VOCs) such as terpenes, ketones and siloxanes. Elevated concentrations can impair the technology and thus the performance of the plant. This is particularly true for membrane equipment. HZI’s innovative pretreatment approach stands out for its ability to handle high levels of VOCs while keeping operating costs low. It’s ideal as an add-on to membrane installations or for upgrading existing plants.
Biomethane plays a crucial role as an alternative to fossil fuels. It can take the form of biogas-based compressed natural gas (bio-CNG) or liquefied natural gas (bio-LNG). HZI’s add-on opens up a wide range of climate-friendly fuel options, for example setting up a bio-CNG filling station at the farm where the gas is produced, or transporting the gas in liquid form to an LNG fuel stop for heavy goods vehicles – a particularly attractive proposition for renewable fuels for transport.
Wet Anaerobic Digestion and Gas Upgrading as a Diversification Option for Farmers
Farmers can diversify into a new field of business with their own wet fermentation technology and downstream gas upgrading installation, processing plant-based agricultural residues or liquid manure to produce biogas and/or biomethane. HZI offers one-stop solutions for raw biogas volumes of 250 Nm³/h and more.
Depending on the customer and the local framework, a wide range of materials can be treated by wet fermentation, e.g. mainly energy crops in Germany, intercrops in France or animal manure and glycerol in Denmark. Energy can also be recovered from food waste. The biogas produced is subsequently upgraded into high-purity biomethane using amine scrubbing or membrane technology. It can then be injected into the gas grid or liquefied for other purposes.
The AD plant’s generous dimensions make it particularly suitable for heterogenous substrates, assuring robust process biology and higher gas output, as well as boosting energy efficiency by preventing settling and floating layers. Another advantage is HZI’s ability to supply a turnkey plant on a one-stop basis and provide the necessary expertise on interfaces of AD plant, upgrading system as well as injection plant.
The appropriate service or remote online support package ensures professional maintenance, with HZI’s experienced experts close enough to their customers to guarantee rapid response times.