BioPower brews up a world first

Wärtsilä has been awarded two contracts by brewing group Scottish and Newcastle (S&N) to supply and install equipment for two biomass-fuelled combined heat and power plants (CHP), one at the company's brewery in Manchester and the other at the Tadcaster brewery.

These plants, of the Wärtsilä BioPower type, are claimed to be the first power plants in the world ever to produce, with high efficiency, both electricity and heat using spent grain as fuel.

The CHP plants, rated at 7.4 MWt and 3.1 MWe, are due to start operation in the first and second quarters of 2009, respectively. They will produce steam and electricity for each brewery, with excess electricity exported to the grid. S&N will earn Renewable Obligation Certificates (ROCs) for its production of renewable electricity. They will also provide some protection from the volatility of the energy markets, as well offering additional security of supply," says Andrew McMurtrie, S&N Project Manager.

When installed, the Wärtsilä BioPower plants will burn a mixture of spent grain and wood chips from local sources. Spent grain is a byproduct of the brewing process, consisting of the grain remaining after the fermentable sugars have been extracted during the mashing process.

The spent grain leaves the brew house with a moisture content of about 80%. It is then passed through a belt press, which reduces the moisture to 58 - 60%, a level suitable for the BioGrate furnace (pictured above), which is part of the BioPower system.