Green energy

Biogas is created by fermentation of organic substances. In nature, this fermentation can happen at the bottom of bodies of water or in bogs, for example, or even in the stomachs of ‘ruminant’ animals (e.g. cattle or sheep). At a biogas plant, the controlled fermentation process takes place in fermentation tanks known as ‘digesters’. These large tanks contain the organic substrate, which is decomposed by methane bacteria. This process, called anaerobic digestion, produces a mixture of gases. Roughly 55% of it is methane, an energy-rich biogas. The digestate, that is left over after digestion, can also be fully reused as a natural, nutrient-rich fertiliser.

There are four stages during the biogas formation process. During hydrolysis or the liquefaction stage, the starting materials (fats, carbohydrates and proteins) are split into their fundamental chemical elements (such as fatty acids, monosaccharides and amino acids). During acidogenesis or the acidification stage, the hydrolysed materials are broken down into organic acids. The third stage, acetogenesis or acetic-acid production, sees the microorganisms transform these materials into hydrogen, carbon and acetic acid, the precursor materials to biogas.
Methanogenesis, or methane production, forms the final stage of the process. Without oxygen( ‘anaerobic’ conditions), the methane bacteria first turn the acetic acid into carbon dioxide, hydrogen and methane. The carbon dioxide and hydrogen subsequently become water and methane. Then, before further use, the biogas is desulphurised, purified and upgraded to the relevant plant demands. If you’d like to find out more about modern biogas plant construction and biogas technology, then we would be delighted to explain the details to you in a comprehensive information and consultation session.

In Germany, roughly 900,000 hectares of maize is farmed for biogas plants, which is about equivalent to the amount of land used for maize farming in the late 1980s. Maize grows to be very tall right before it is harvested. It’s difficult to oversee and hence is seen as something “quite dominant”, though its size also offers a benefit: maize produces more biomass per hectare than almost any other crop. What’s more, it requires little water and fertiliser, and yet still forms a great amount of gas during fermentation. The farming of bioenergy crops has also had a significant part in stabilising incomes in the agricultural sector. Farmers benefit from higher profits when they sell their harvest, while biogas plants offer many farmers a secure foundation for generating income in times when milk and meat prices are low. (Source: Fachverband Biogas e.V.)

The electrical output of a biogas plant ranges from roughly 75 kW (a small plant) to several megawatts (a large plant). The amount of power that a plant generates depends on the amount of biogas produced. A farmer can expect to obtain 400 to 500 m³ of biogas per livestock unit per year. One hectare of pasture grass can produce up to 7,000 m³ of biogas per year and energy-rich plants such as turnips or maize can produce even more. This means that building a biogas plant not only profits the climate and environmental protection, but is also a sustainable investment in a farm’s future viability and profitability.

Producing biogas requires a permit. If you wish to operate a biogas plant, you need to be familiar with the legal requirements and complete all the necessary formalities before starting construction. We’re happy to support our clients with their applications for permits. We can boast over 20 years of knowledge from applying and developing these systems, so we’re closely familiar with the individual steps and processes. We clear a path through the administration & government jungle of forms so that your biogas plant is fully compliant with applicable law and you can take full advantage of all potential funding and subsidies granted by the state and the nation.

Once the preparations are complete, you can get started building your biogas plant at your intended location. We perform all the required inspections and professional acceptance testing before putting it into routine operation. If desired, we can also make a separate arrangement to guarantee a specific electricity, gas or heat yield from your plant, giving you full certainty for your planning and finances.

Using our modern process control system, BioControl, we ensure that biogas plants always perform at their best potential and at an optimal profitability. The software was developed by experienced bioconstruct technology specialists and can also be retrofitted to older biogas plants. It can help you to configure your plant perfectly to your needs (e.g. for an on-demand-based electricity generation) and enjoy a precise overview of individual operational processes at all times.

Unfortunately, animal waste and slurry can’t be put straight into vehicle fuel tanks (just yet). Nevertheless, there’s an alternative that’s just as genius: our biogas plants digest slurry and manure and produce biogas from them. The main products created from this are carbon dioxide and methane. These two are separated from each other and purified using biogas upgrading systems. The carbon dioxide is then purified again and compressed. The end product is ready to dispense into bottles and be transported to soft drink bottling lines to carbonate beverages. Alternatively, it’s also possible to make dry ice – which is already done at our Crofthead biogas plant (see our testimonials).

The methane embarks on an even-longer journey. It’s usually fed into the gas network at the same location as the biogas plant. Then, at any other point in the gas network, an equivalent amount is extracted back out of the network and conveyed to a liquefaction facility that turns the biomethane into bio-LNG (liquefied natural gas). Heavy goods vehicles can use this as fuel and drive up to 1,000 km per tank of it (compared to roughly 1,500 km on diesel), making it an excellent alternative to diesel. The best part is that both the carbon dioxide and LNG can be produced in an environmentally friendly way, while generating and marketing them together with CO2 certificates provides for great profits. This creates a perfect synergy between economy and environment.

bioconstruct plans, builds and maintains plants for farms, medium-sized plants for community use and waste-to-energy plants for industrial use. We have the right technical solution ready for any type of input material or we can create a solution together with our partners. When it comes to utilising biogas, we offer cogeneration and ORC plants as well as biomethane upgrading plants and technology for further processing of the gas. Accordingly, we can generate valuable fuels such as CNG or LNG out of biomethane and even make good use of the carbon dioxide from biogas.