Biogas connects rural and urban communities and demonstrates how the green transition can be built on local resources. It plays a particularly important role in industries where electrification is not yet possible and where production processes require very high temperatures.
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The answer lies in the landscape
There is no one-size-fits-all approach to the green transition. It often builds on the resources available in the local environment.
Norway harnesses hydropower from its mountainous terrain, Iceland utilizes geothermal heat from its volcanic landscape, and Morocco’s deserts are ideal for large-scale solar power.
In Denmark, agriculture shapes both the landscape and the energy system. Agricultural activities generate manure and other organic residues, which can be used as a valuable resource through biogas.
Biogas is a solution that delivers on multiple fronts at once. It supports farmers and industry, reduces CO₂ emissions, and strengthens energy security.
Denmark is among Europe’s biogas frontrunners, and Sønderborg has gone even further: the area is fully self-sufficient in locally produced biogas.
Behind the results
From waste to resources
A biogas plant works much like a cow’s stomach.
When a cow eats grass, bacteria in its stomach break it down and produce methane and CO₂. A biogas plant uses the same biological process – but with manure and other organic residues such as food and industrial waste. The key difference is that, instead of letting the gases escape into the atmosphere, the plant captures them. And that makes all the difference.
The process produces roughly 60% methane and 40% CO₂. The methane can be used as energy and replace fossil gas in the grid. The CO₂ can either be stored or reused, for example in food production, to produce more methane, or in Power-to-X processes, where it can be converted into green fuels for ships.
Denmark has produced biogas since the 1980s, and today it represents a strong collaboration between agriculture, energy and industry. In fact, Denmark has the highest share of biogas in the gas grid in Europe: around 40%, with a national ambition to reach 100%.
In Sønderborg, biogas production has reached a level where the area is fully self-sufficient in gas. Two biogas plants in Kværs and one in Glansager together produce enough green gas to cover the region’s total gas consumption.
Biogas plays a unique role in the energy system by serving sectors that cannot be electrified. It is, however, a limited resource and must be used strategically. For private homes, district heating and heat pumps are the most efficient solutions. But in industrial processes that require very high temperatures, biogas remains the greenest alternatives to fossil fuels.
Local farmers powering Sønderborg’s transition
The biogas story in Sønderborg is not only about large-scale facilities. Several local farms have established their own on-site biogas plants, converting manure and other organic residues into energy. These plants use biogas in three different ways, illustrating the technology’s flexibility.
In Nordborg, a farmer converts biogas into electricity and supplies it to the power grid.
In Kværs, a local pig farm has gone a step further by connecting his biogas plant directly to the gas grid, contributing to the regional gas supply.
At Gråsten Agricultural College, the biogas plant runs exclusively on manure from the school’s own cows and pigs. It supplies both electricity and heat to the campus buildings and serves as a living learning environment where students gain hands-on experience with modern, circular energy production.
What all these initiatives share is a simple principle: using local resources first. This creates local value, reduces agriculture’s climate footprint, and decreases dependence on imported gas – while demonstrating how biogas can be scaled and adapted to different contexts.
The world’s first Power-to-Gas plant
Many people have passed wind turbines standing still despite strong winds. This happens because electricity is only produced when it can be used, because it is quite difficult to store. Biogas offers a flexible solution in this context.
In Glansager, Sønderborg is home to the world’s first Power-to-Gas plant integrated with a biogas facility. The plant makes it possible to utilize surplus electricity from wind and solar when production exceeds demand. Through electrolysis, electricity splits water into hydrogen and oxygen. The hydrogen is then fed into the biogas process, where it reacts with CO₂ and forms additional methane.
The result is that the biogas plant produces much more methane from the same amount of residual materials.
The facility can be switched on and off as needed, allowing it to adapt to periods of surplus green electricity. In this way, Power-to-Gas helps both to balance the energy system and to increase the production of green gas.