Noisy, smelly HGVs used to thunder across the Swiss Plateau, transporting pig manure from Lucerne to farms in several other cantons, until enterprising local farmers came up with an innovative plan to build a biogas plant.  In 2010, their efforts were justly rewarded, when they won the “Watt d’Or”, the Swiss Energy Prize, in the Renewable Energies category.

In 2006, the canton of Lucerne stank to high heaven and the farmers were far from happy. The amount of manure produced by the 425,000 pigs being reared in the canton exceeded local demand. The watercourses suffered from the overabundance of muck and slurry, while the noxious emissions were more than the noses of local residents could bear. Slurry pits were brimming over and dung heaps grew ever bigger. The excess slurry was dispatched to farms in several other cantons, heralding the advent of "manure tourism". However, the farmers had to cover the transportation costs themselves (up to 50 Swiss centimes per kilometre and per tonne), a situation they found less than satisfactory. So, what could they do to clean up this mess? 

Farmers join forces to combat overuse of fertilisers

The biogas plant in Inwil is testament to the resolve of the farming community. Together with a number of partners (Erdgaszentralschweiz AG and Energie Wasser Luzern ewl), local farmers founded SwissFarmerPower Inwil AG in 2008, the largest biogas facility in Switzerland. It was also highly innovative: it was the only facility of its kind to combine wet and dry fermentation, making it possible to convert both solid and liquid biodegradable waste like plants, manure and slurry into biogas, leaving behind only copious amounts of compost. The resulting gas is fed into the regional natural gas network and sold at the fuelling stations of the local energy and water supplier, Energie Wasser Luzern.

From pig manure to biogas

In Inwil biodegradable waste is turned into biogas, a CO2-neutral fuel for natural gas vehicles. The plant is able to process a huge variety of waste ranging from plants and coffee grounds to pig manure and even liquids such as slurry, oil from the food industry and sugared water left over from milk production.

Dry fermentation
Once sorted and shredded, the waste is transferred to a dry fermenter. This huge tank is always two-thirds full. For three weeks a paddle slowly stirs the contents, the temperature of which is kept at a constant 55 degrees Celsius. The resulting raw biogas is approximately 60% methane and 40% CO2.

Wet fermentation
Like solid waste, the liquid waste is transferred to a huge tank. Kept at a temperature of 38 degrees Celsius, the biodegradable mass is blended for between 15 and 20 days to produce raw biogas.

Finally, the biogas is collected in green storage domes.

Working at full capacity, the plant annually produces 18 Gigawatt hours of energy in the form of biogas. The biogas is converted to  natural gas and fed, for example, into the fuelling stations of Energie Wasser Luzern. Enough natural gas is generated to fuel some 2,000 natural gas vehicles, each covering 12,000 km a year. This equates to a saving of around 2 million litres of petrol and 4,000 tonnes of CO2.

Swiss energy award - Watt d’Or 2010

The 2010 “Watt d’Or” recognised not only this innovative biogas facility but also the 72 farmers who together with other investors showed they were not scared to try something new. In biogas, the Rolls Royce of renewable energies, they saw an innovative solution to a revolting problem.