Farm Ireland

Tuesday 12 December 2017

Methane capture churns cheesemaking operation

The Fahringers' 'gas bag' stores the methane produced from the digester
The Fahringers' 'gas bag' stores the methane produced from the digester
Cow slurry is scraped into the Fahringers' concrete tank anaerobic digester

Bruce Lett

A short trip across the German border into Austria, again at the foothills of the Alps, we visited dairy farmers and cheesemakers Toni and Martha Fahringer.

Like so many farm dwellings in rural Germany and Austria, their house, cheese factory and cattle were all under one roof, albeit a very large roof.

When renovating their cow shed two years ago, they decided to install a biogas unit to supply the heat requirements for the cheesemaking process.

There are several different types of cheese produced by the Fahringer's, in total amounting to a yearly production of 8,000kg.

All the cheese is produced from milk from their own cow herd. In total, 35 Simmental cows yield 6,000 litres of milk each a year. They are fed on hay cut three times a year from the farm's 25ha down in the valley.

The family also has 35ha on the slopes of the Alps, where in spring and summer the cows graze these pastures. It is the grasses and herbs from these slopes that gives the milk and cheeses their distinctive flavours.

Despite having four stomachs, cows cannot digest grass completely efficiently. It is this undigested part of their feed that breaks down even further in the anaerobic digester to produce methane gas.

At the dirty end of the anaerobic digestion process, an enclosed shuttered concrete slurry tank provides the environment that is required to produce and capture methane gas.

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When housed, automatic scrapers deliver the cow dung into this mass concrete tank where the methane is produced. The gas is gathered and stored in a large flexible 'bag', which is housed and protected in a typical Austrian wooden shed a few metres away from the slurry tank. Storage capacity in this bag is 60m3.

The stored methane is simply burnt in a conventional central heating boiler, which has been adapted to burn the gas. This provides the majority of the heating requirements for the family and its cheesemaking business throughout the year.

A conventional stove is used to provide additional heat during extremely cold spells. Construction of the slurry tank cost the family just €25,000.

The Fahringers' have their own website, check out

Indo Farming