Biogas systems are environmentally friendly and efficient. They must, however, be ‘fed’ with similar care to cattle, pigs and chickens.Andreas Hilbing produces power and heat from liquid manure and silage at his farm in Vreden. He uses a wheel loader with mobile weighing system for dosage. This allows him to achieve optimal loading of the system with maximum yield.
Three are approximately 2,700 biogas systems in Germany, producing just 1% of the power that is produced in Germany. One of these systems is on Andreas Hilbing’s farm in Vreden, close to the Dutch border. He began thinking about the production of power and heat from biomass in 1999, thus becoming a farmer of energy.
High level of efficiency: power and heat are utilized
Two large fermenters are located behind the farmyard, where billions of bacteria produce fermentation gas from the biomass. The gas is dried and added to a 500 kW gas engine, which uses it to produce power and heat. Hilbing uses approximately 10% of the power for his own use and for a turnery that is located on the farm; he feeds the majority of the power into the mains network. The heat is also utilized; a drying system is located in a disused stable and this processes the fermentation residue into granules using the heat. These granules are a popular fertilizer. This coupling of power and heat creates the prerequisites for a degree of efficiency that is substantially higher than conventional power plants.
Dosing and mixing proportions must be correct
The bacteria processes the entire bio residue into fermentation gas but for the system to run at an optimal rate and for everything to stay in the biologically safe range the mixing proportions of liquid manure and silage or other secondary raw materials must also be correct. And more or less solids must also be added: the more energy in the materials, the less is required. If this rule is not adhered then the system will produce more gas than necessary and the excess will be burned off – or too little gas is produced and the engine is insufficiently exploited. Andreas Hilbing tells us that he always tries to keep the system running at full load.
As various organic wastes are ‘fed’ into the system, e.g. overproductions of onions from the Dutch neighbours, you must also know how much of each solid should be added to the liquid manure. This quantity must then be dosed as precisely as possible.
Current weights and total weights are recorded
Andreas Hilbing has now equipped a wheel loader with mobile Pfreundt weighing system for this task. The Company, that is located in neighbouring Südlohn, specialises in mobile weighing technology with over 25 years of experience. A total of over 15,000 Pfreundt weighing systems are in use worldwide – e.g. in wheel loaders,excavators , harvesting machinery and disposal vehicles.
Measurement sensors in the lifting system of the loading shovel supply the weighing system with information to exactly determine the weight of the shovel contents and to output them to a clear display unit. Its static measurement process enables the scale to add exact partial loads in individual shovels.Remainders that are not required can be weighed back if necessary as the weighing electronics of the WK 50-S show not only the current shovel contents but also registers the total weight – a property that Andreas Hilbing and his staff always use if they fill the container with silage twice in one day.
More exact ‘feeding’ of the system
Here the silage and other solids are no longer dosed using shovels but rather in exactly calculated kilograms – and that is a great help for optimisation. Hilbing tells us: “We have found that up to 200 kg more or less silage is transported depending on the driver. Now we can give clear directions how many kilos should be added in each case”. This precision is noticeable; the system is now loaded to ideal capacity and is always operating at the optimal level. This then also affects income as Andreas Hilbing can then produce more power and heat. From this perspective it is no wonder that Hilbing is satisfied with the Pfreundt weighing system: “I should have purchased this kind of scale much earlier”.
Further plans: new feed container with automatic charging
Hilbing is currently planning the construction of a new feed container to charge the fermenter automatically about eight times a day and thus assure continuous supply – on the principle of many small meals being better than fewer large meals. The wheel loader with the mobile scale will continue to be used for the exact determination of silage quantities.
Andreas Hilbing has a high opinion of biogas use – and he is always open to new technologies that he can use. He is now adding enzymes to the fermenters that accelerate the fermentation process and thus increase the system’s efficiency. He is also currently planning to construct a second biogas system of a similar size together with other farmers/energy producers. And when it comes to the detailed planning of the silage feed he will be including a mobile weighing system by Pfreundt at an early stage.