1 February 2011

Incentives implemented by the German government have led to a surge in over 6,000 anaerobic digestion (AD) plants being built across the nation.

However, the vast majority of these are large-scale, around 1MW or above, thus affecting the tipping fees for waste food – which now stands at between €10 and €20 per tonne, down from €60 to €80 per tonne – and biocrop prices to such an extent that many could become economically unavailable.

But small-scale, distributed AD facilities have the potential for an economically stable solution for locally produced biogas, according to Craig Benton of Composting and Recycling Consultants.

Providers of AD and biogas equipment usually starts at around 250kW and this can sometimes encourage the importation of feedstocks which, as Benton explains, can be economically uncertain.

In view of this, Benton went on the highlight a new system developed by Austria-based Bio4gas that starts at 20/25kW. It is also available in a 50kW size. This smaller sized system allows farmers to produce heat and power from animal slurry sourced from their farms only. The system also produces digestate, which can be used as a fertiliser.