When the maize harvest gets under way, things get busy at Gut Rutenstein farm, with large machines in constant operation, operating alongside the farm’s biogas plant. The estate harvests the maize kernels and crushes them before storing in silos. “We’ve had great success in doing this for a number of years,” explains Mr von der Decken. “Using this method, we get a concentrated feed that can replace conventional purchased concentrates, which are often imported from overseas, and need to be dried elsewhere using an energy-intensive process.”
This cornmeal is fed to the farm’s 500 dairy cows – an enterprise taken on a few years ago. And the company’s biogas plant, with 500 kW electric power and double flex power output, is fed with its self-produced concentrated feed, in addition to corn and grass silage, dried chicken droppings, pig and cattle manure.
Since the biogas plant began operating in 2012, the electricity generated has been fed into the northern Lower Saxony grid. The plant also produces sufficient heat to supply the neighbouring educational centre, retirement home, country store, and 17 individual houses, including the brick build Rutenstein Castle. The biogas plant is only around 5km away from the decommissioned Brokdorf Nuclear Power Plant, which is located on the other side of the Elbe, on the north side of Schleswig-Holstein.
At the Gut Rutenstein farm, the maize kernels are crushed before being poured into silos in order to increase the energy yield.
The crop gets processed.
The busy activity of the biogas plant against the inactivity of the nuclear power plant embodies the energy course taken by the Federal Republic of Germany in the past two decades – away from nuclear power, away from fossil fuels, and towards renewable energies.
To a large extent, Mr von der Decken is well established in the renewable energies sector, not only having built the biogas plant, but also with the construction of wind turbines on his own premises, and solar photovoltaics on top of courtyard buildings. “Of course, every successful farm must constantly deal with energy issues,” he emphasises. On his farm he grows wheat, barley, oats, oilseed rape, maize, field beans, sugar beet, and grass on 500ha.
Every successful farm must constantly deal with energy issues.Herwart von der Decken
Despite the energy price crisis, the businessman, now in his mid-forties, says he doesn’t worry about the scaremongering going on at the moment. “The price hikes are a factor, no question. However, they are somewhat overrated. “If the price of diesel per litre rises from €1.20 to €1.70, that will end up being only €50/ha. Ultimately, that is not a decisive cost, it is much more important that I get good harvests and do the agricultural work that I have to do,” he says.
By far, the majority of the estimated 10,000 biogas plants in Germany are operated by agricultural businesses like to one in Freiburg an der Elbe. Overall, agricultural biogas operations in German generates gross sales of €5bn to €6bn, with energy crop inputs of around 2m ha comprising mainly maize, but also grass, sugar beet, clover grass, hybrid silphium, flowering mixtures, and fruit. According to industry experts’ estimates, the proportion of manure and slurry being fermented in biogas plants is currently around 25-30%.
And so, with regard to the pending requirements for reducing emissions in agriculture, there is still great potential to achieve ambitious climate protection goals, with a further increase in use of liquid and dry manure. Further development in the biogas process is also possible, with options to separate the carbon dioxide contained in the biogas – biologically or technically – and convert it to methane, in combination with hydrogen. How quickly this option will be put into practice on farm is not yet clear.
It is also difficult to estimate whether the direct injection of biomethane into the gas grid, or for supply at filling stations, will increase significantly in times of gas shortages. So far, biomethane has accounted for only around 1% of Germany’s gas requirements. Theoretically, this proportion could increase significantly if the vast majority of biogas plants operating today were to produce gas instead of electricity and heat. However, such a change cannot be made overnight. Currently, biogas electricity is extremely important for a stable electricity grid because it can close the generation gaps, even in the so-called dark times when the sun is not shining, and the wind is not blowing.
In order to cover this demand, which skyrockets during peak loads, many biogas plants have been equipped with additional capacity, so that, depending on market requirements, they could increase the power output two, three or even four-fold. For companies that have invested in this so-called flexibility in recent years, a sudden switch to methane feed-in is, understandably, not possible.
Important contribution to Germany’s energy supply
In late autumn, a note from the Federal Network Agency showed the importance of biogas, and bioenergy as a whole, for Germany’s power supply in the energy transition period. It reported that, on the grey and almost windless 29th of November, electricity generation from biomass was even higher than that from wind, and far ahead of that of solar photovoltaics. In fact, according to industry insiders, there is now a definite demand for biogas on the energy market. Especially for the sort of biogas which is considered to be particularly sustainable within the European biomass strategy – those coming from waste, liquid and solid manure, or organic farming, and offers great economic opportunities.
Someone like Lothar Braun-Keller, one of the few in the Bioland Association who relies on biogas production, is of course happy to hear this. He estimates that there are around 180 plants in Germany that do not produce “agro-biogas”, as he puts it, but rather “eco-biogas”. But whichever gas is used, in the end “no one likes us grubby urchins, the ones that have anything to do with biogas,” says Mr Braun-Keller with a smile. And he remarks that he is not worried about this bad image, he can live with it.
In operation since 1996, when his first biogas plant was installed with a capacity of 45kW on his farm in Leibertingen on the Swabian Jura, the system has grown. Today, with a flexible operation, his plant produces 860kW. In addition, there are also large solar photovoltaics on farm buildings, which help cover a large part of the farm’s own needs.
At the same time, the biogas plant on the farm supplies two local heating networks, operated by the municipality of Leibertingen, with a satellite co-generation unit. During the summer, Mr Braun-Keller also offers contract drying for neighbouring farmers. The fermenters are fed a total of 13,000t/year, with 64% of total input coming from grass and clover, 35% from cattle manure, and the rest made up of mixed silphium – about 2.5ha, comprising 0.6% of the total substrate.
I consider the positive effect of biogas on agriculture as a whole.Lothar Braun-Keller
Mr Braun-Keller is definitely not complaining, because the integrated biogas plant on his farm, which he runs with five full-time employees and 10 other employees on a €450 per month basis, has proven its worth. Despite green energy production, he is, first and foremost a farmer. “I consider the positive effect of biogas on agriculture as a whole,” he adds. He believes that biogas production should serve agriculture without any compromises – which clearly is being done at the Leipertingen site.
“Our humus-poor, calcareous soils in the Swabian Jura benefit from the nitrogen-rich fermentation residues. Without being able to precisely define the humus content at present, we simply find that our yields, in a diverse crop rotation, are higher than before – despite the drought that we have experienced here in recent years,” Mr Keller-Braun states with satisfaction. He believes that 9,000mW of electrical output from sustainably produced biogas to be achievable; the methane equivalent of this could help cover a large part of the previous gas imports. That’s a good outlook.
Biogas in Germany
There are around 10,000 biogas plants in Germany. The vast majority of these are run by farms. The installed capacity ranges from less than 100kW (slurry) small systems to multi-megawatt (MW) satellite co-generation units. All in all, the German biogas industry has an output of almost 4,000mW, and almost 2,000mW of flexible capacity. The waste heat produced during power generation can supply the equivalent of 1.1m households with sufficient heat, and many villages throughout Germany are already benefiting from this. In addition, a small proportion of the biogas plants, around 250, feed methane directly into the gas grid; the carbon dioxide contained in the biogas is separated using so-called methanation. This separated CO2 is not yet being used, but that will soon change because more methane can be produced from it by using hydrogen. The beverage industry is also interested in this valuable raw material.
The first bio-LNG plants are currently being built in Germany, like in Darchau in the easternmost tip of Lower Saxony, where biomethane is used to produce sustainable fuel.