Pioneering spirit 01 August 2012

Biomass power generation is one of the keys to renewable energy diversity. Brian Tinham examines a next generation, modular version that is capturing the imagination

One of the first of a new generation of biomass power plants, currently attracting worldwide interest for its potential to transform adoption, costs, timeframes and fuel handling flexibility, is being commissioned this summer is Bagnolo di Po, Rovigo, Italy. The multi-million pound project covers the construction of a renewable electricity generation plant in a rural region that hitherto would have been met with strong local opposition, had traditionally large-scale power plant had been proposed. Yet it is going ahead with the blessing of planners.

And that's one of the key points: Staffordshire-based Biomass Power, set up in 2009, brought together industry knowledge from the biomass and power sectors, and redesigned conventional plant from the ground up – or rather along – not only to make it more acceptable to local communities, but also more practicable. Engineering director Martin Riley explains that, while biomass plants have been around since 2000, a major issue has been their height – typically in excess of 30m. "Potential development was being delayed as planners and communities objected to large-scale building construction," he says.

Add to this the considerable timescales involved in the thermal design of the process technology and delivery of the building on-site, and it was clear that an alternative approach was required. "The key to our offering has been our ability to create the entire biomass gasification process in a less intrusive, horizontal and modular, turnkey format," states Riley. "We design and manufacture the plant at our premises and then turn up on site to effectively bolt the design together, thereby saving significant amounts of time and expense," he explains.

"This approach allows us to confine the entire biomass power plant process technology within sub 10m high buildings and, as a result, counteract planning objections about scale – as well as drastically reducing the construction timeframes. Our plants, for example, do not look out of place within any industrial site."
Biomass Power focuses on smaller-sized power stations of up to 5MWe, viewing them as the way forward for green power in locations that cannot tolerate large buildings. But that's not the whole story: the firm's approach is based on local supply, seeking fuel for its plants from locally sourced waste materials, whatever they may be. Its process technology has been designed to handle a wide envelope of waste fuel streams, including forestry, agricultural residues, straw and miscantus.

The new Italian plant has a capacity of 15—20MW thermal and is rated at 3.25—4.25MWe gross, producing green electricity for export to the grid. It is based on an optimised gasification process, followed by secondary combustion capable of handling fuels at up to 30-40,000 tonnes per year. In the Bagnolo region, as well as using local farming residue as fuel, electricity generated by the plant will provide power to the local hospital and save an estimated 12,000 tonnes of carbon annually.

In brief detail, a heavy duty moving floor feeds the fuel into a reciprocating step grate via a metering device. The grate gasifies the fuel to produce a volatile mixture, which is then burnt at above 850°C to ensure complete combustion. Once gasification and secondary combustion are complete, the hot gas is transformed via a water tube boiler into high-pressure steam at 450°C, and hence to electricity, using a vacuum condensing turbine. Finally, once the hot gases are released from the boiler at low temperature, they move into a dust filtering process that monitors flue gas emissions to ensure compliance with local emission standards.

As for the monitoring and control system, Biomass Power and solution partner Capula specified Siemens PCS7 process management system. "Capula identified the standardised approach and operational efficiencies we could obtain using Siemens' PCS7 system," comments Riley.

He cites the sophistication of control but also the system's fault-finding functionality and Siemens' worldwide back-up and technical support. "[Those] made it the ideal choice as the control system for our turnkey power plants. In a rapidly changing marketplace and with power plants expected to be operational for up to 25 years, we now have the assurance that, by using PCS7, we are ... future-proofing our plants with a standardised approach to the automated control system."

Brian Tinham

Related Downloads
43945\P023_PENG_AUG12_LO.pdf

Related Websites
http://www.biomasspower.co.uk/

This material is protected by MA Business copyright
See Terms and Conditions.
One-off usage is permitted but bulk copying is not.
For multiple copies contact the sales team.