German biogas plant manufacturer Weltec Biopower is building a biomethane plant near Pontefract, West Yorkshire, for Lanes Farm Energy, a gas-to-grid project developed by Aqua Consultants.
The plant will go live later this year and deliver around 7.3 million cu m of biomethane to the gas distribution network. This is sufficient to supply about 9,600 households.
Locally sourced feedstock has contributed to the project’s sustainability, said Weltek sales manager Dr Kevin Monson. “Food leftovers account for more than half of the 80,000 tonnes a year feedstock, and it also uses manure, grass silage and hybrid rye.”
The solids are fed through two walking-floor feed hoppers of 110 and 220cu m, followed by two MultiMix units. These remove foreign objects, then liquefies, shreds and macerates incoming solids to make them into an easily pumpable, mixed and digested liquid.
“The mashing and shredding process ensures bacteria can access the substances in the digester faster and will reduce the energy required for mixing,” said Carsten Hesselfeld, sales engineer at Weltec. “Liquids will be fed in controllable volumes directly to digesters from five pre-storage tanks.”
Gas production takes place in four stainless-steel digesters, each with a capacity of 6,848cu m. Weltec has opted for membrane upgrades to transform the biogas into high-quality biomethane.
In the separation process comprising several stages, the raw biogas will be refined without methane slip, producing around 850cu m an hour of biomethane suitable for feed-in. The remaining digestate can be used as high-quality fertiliser.