AD Plant Slashes Electricity Bills At Singleton Birch

Months of construction work are now delivering major cost savings for the UK’s leading independent lime supplier.

Singleton Birch,which has a quarry at Barnetby, North Lincolnshire, is noted for its progressive thinking and hit on the idea of building an Anaerobic Digester plant (AD) on the surface of an old quarry at its Lincolnshire site. It is powered by silage and other biomass.

But, whilst the benefits were considerable, it wasn’t without challenge, as HBPW’s Managing Partner, Paul Withers, describes.

“Singleton Birch decided to site the proposed plant on the surface, and in the middle, of a quarry which had been loose backfilled to a depth of approximately 18 metres.

“ However, the suppliers of the plant required stringent control of settlement before siting their equipment. Subsequently boreholes indicated that the quarry was filled with loose granular material varying from small aggregate to large boulders, and it was concluded that use of piling was not a practical proposition.”

HBPW put forward a scheme to pre load the proposed plant area with about five metres depth of material brought from other areas of the Singleton Birch site. Settlement of the surface of the quarry under the pre load was monitored over a period of time and, when settlement was observed to have ceased, the pre load material was removed so that construction work could continue.

The other factor to be considered was the problem of leachate.

“Before the Plant could be constructed a rubber membrane needed to be placed across the entire site to prevent any toxic leachate – a by-product of the vegetation fuel used in the AD plant – draining into the ground.”

The AD plant at Singleton Birch enables maize and other fuels i.e. sugar beet and grass to be brought straight to site and put into three large silage clamps. Although leachate drains from the grass as it is being stored in these clamps, the rubber membrane used to cover the standing area, prevents the toxic substance draining into the ground.

“Thereafter the maize is moved from the clamps to the digester tanks where, starved of oxygen, it produces methane which is then removed from the surface of the material and used to drive the turbines which produce electricity. As Singleton Birch are a massive electricity consumer this offers a major cost saving to them. The Plant was initially installed as a 0.5MW plant but will be ramped up to 2MW by the end of 2015,” added Paul.

The plant was officially opened by top UK businessman, Lord Haskins.