When it comes to green energy in agriculture, biogas plants are often the first systems that come to mind. Most are installed on farms, with only a few operated by municipalities or local authorities. But a biogas plant won‘t run itself. It needs auxiliary energy to operate pumps, screw conveyors and the agitator, among other components. Drawing this energy from the grid is rarely economical, as utility prices have long exceeded the feed-in tariff for electricity.
30 kilowatts for auxiliary power
Bavarian farmer Johannes Steuer developed a solution to this challenge together with IBC Solar, a system provider for PV and storage systems. They were supported by experts from Elektro Kondra, an IBC specialist partner. Steuer runs his farm in Burgkunstadt, a small town in the Franconian district of Lichtenfels. Manure from his livestock feeds the biogas plant, which supplies two combined heat and power (CHP) units with the gas produced.
Auxiliary power is supplied by a 30 kilowatt photovoltaic system. In purely mathematical terms, it generates enough electricity to cover more than half of the biogas plant’s annual auxiliary power demand.
However, because solar energy is not always available when the pumps, agitator and screw conveyors are operating, the PV system can actually supply only around a quarter of the biogas plant’s auxiliary energy.
Storage unit covers peak loads
To improve this value and to be able to operate the biogas plant with its own electricity even in times without sunshine, IBC Solar has installed an additional battery storage system. This temporarily stores the solar power that is not directly used by the consumers in the plant.
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To improve this share and enable the biogas plant to operate on self-generated electricity even when the sun isn’t shining, IBC Solar installed a battery storage system that temporarily stores surplus solar power not immediately used by the plant’s equipment.
Remaining energy flows into the grid
With a usable storage capacity of 72 kilowatt-hours, Johannes Steuer can double the power supply of the biogas system with his own solar electricity and thus also run it almost half with energy from the sun in real terms in the annual balance. To achieve this, he uses more than three quarters of the solar power generated.
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He feeds the remaining quarter into the grid and receives compensation under Germany’s Renewable Energy Sources Act (EEG). “The biogas plant’s consumers are also easy to regulate, so self-consumption and the degree of self-sufficiency increase,” says Johannes Steuer. “This allows me to make good use of the storage capacity.”
Find out how Johannes Steuer commercialises his bioenergy and how the system becomes economical in the special report on PV in agriculture.
Download the free special here
