Biogas Services

Heat & Power Services were already maintaining an energy saving CHP system at Mauri Products when changes in government legislation meant that effluent from the yeast plant, originally disposed to sewer, now had to be treated. To have paid a third party for the disposal would have made the whole plant uneconomic and so the company constructed a bio-waste treatment plant in which the main product from this (methane + some hydrogen sulphide) was burnt on a steam boiler to release a higher value product i.e. steam. Heat & Power Services however advised that the gas would be better burnt in a gas engine to produce electricity, steam and hot water (a 10-fold higher value product). As hydrogen sulphide is a contaminant in the bio-gas and would be damaging to a gas engine this required prior removal.

Further government initiatives on renewable energy meant there was a special payment rate for any electricity produced by renewable means (‘ROCS’ scheme). At that time April 2006 this was 10p/KWh produced compared to 5p/KWh they pay at present. The savings opportunity was compelling. 

Intervention:>
Initially the tender issued by Mauri Products was to convert the existing engine to run on both natural gas and the bio-gas (scrubbed of hydrogen sulphide). However Heat & Power Services successfully argued that the very best course of action was to install a new bespoke CHP plant with dedicated engine and bio-gas treatment plant (hydrogen sulphide removal). As the projected monthly income revenue and savings from such a plant were so large, Heat & Power Services argued that with the price and delivery time on a new engine (£180,000 and ~1 year) a more profitable option would be to acquire a reconditioned engine foremost. As such Heat & Power Services rebuilt an existing Caterpillar engine in Holland and installed and commissioned it within 4 weeks for £100K.  We also installed and commissioned a bio-gas treatment plant, a heat recovery system with boiler, a heat recovery system for hot water and finally heat rejection equipment. The treatment plant continues to be maintained by us alongside the CHP plant. We also designed and installed the control panel, and programmed the PLC for the bio-gas treatment plant /engine interface so as to minimise maintenance down time.

Outcome:
This efficient harnessing of renewable energy has meant huge savings to Mauri Products. The bio-gas (a free by-product of the waste treatment plant) generates electricity, steam and hot water, all of which is re-used by the main yeast plant. Typical availability of the CHP system is (96%?). Recovered hot water is even used to heat the waste effluent that is producing the bio-gas! The company recovered their start-up costs in a very short space of time and continue to benefit.