Combined heat and power plants (CHP) convert the biogas into electricity and heat. The green electricity is fed into the grid, and we use the heat to dry our high-quality special feed called ProEnMune. We thereby attain a total utilisation level of more than 80%.

The actual generation of energy starts after the biogas has been treated. Combined heat and power plants (CHP) burn the methane and use the kinetic energy to produce electricity. In addition, heat is created just like in any combustion engine. In contrast to a car, it is not simply released to the outside world, it is instead used specifically for heating or drying. Through what is known as cogeneration, combined heat and power plants utilise a large amount of the energy. This is referred to as a high degree of efficiency or utilisation (degree of utilisation = useful energy for electricity plus useful energy for heat divided by the energy used). A modern large power plant based on coal reaches a level of efficiency of approximately 45 percent. In contrast, a CHP plant attains almost 90 percent. And there is still another benefit: During combustion in the CHP plant, the amount of carbon dioxide that results is only the amount that the plants absorbed while they were growing. The CO2 balance is therefore neutral (in contrast to energy recovery from fossil fuels). For this reason, biogas plants with combined heat and power are an important component for generating energy in the future and make an effective contribution to reduction of CO2 emissions and hence achieving the climate goals.

In Soltau, we use three Jenbacher CHP plants of the type J420 GS. That way we produce 5.6 MW of thermal and 4.2 MW of electrical energy, which corresponds to the power consumption of approx. 7,000 4-person homes. We use the heat right on-site for the manufacturing process of our special feed called ProEnMune as well as for drying wood pellets. Naturally, we can match the energy demand of the drying facility exactly to the combined heat and power plant, and are not confronted with fluctuating demand, as would be the case if the heat were used for a residential building, for example. This way, we achieve a very high level of efficiency of approx. 85% and meet the requirements of the renewable energy legislation for CHP-operated renewable raw material plants.

The waste heat of the CHP plants is released into thermal oil by means of a heat exchanger. Afterwards, the oil is used to heat air, which flows into the dryer from the bottom, which is where the liquid yeast cell walls are dried for our special feed ProEnMune, for example. This indirect route via the thermal oil ensures that the yeast cell walls have no direct contact with the CHP plant, its exhaust air or the thermal oil.
The dryer consists of a large steel tank with a rotor on the bottom. The rotor has small, solid beaters. These beaters are used to inject the hot air into the dryer. The liquid yeast cell walls (called yeast milk) are injected from the side. The beaters on the rotor atomise the yeast milk into small droplets by their fast rotary motion. The moisture evaporates and is channelled out of the tank as water vapour. This results in dry yeast cell walls of different grain sizes, which are divided and sorted in a screening process. The special feed ProEnMune is filled in sacks and is ready to be sold. We offer three different grain sizes.