Biomass power station aims for zero carbon footprint

Farmers from up to 20km away supply feedstock to the plant, converting what was a waste product into a valuable resource and thus helping enhance the economy of the whole region. Encouraging agriculture and protecting the environment by producing zero net carbon dioxide emissions. The Bioenergy Park in Bondeno Ferrara, midway between Venice and Bologna, was built and is operated by CPL Concordia, a company which is at the forefront of renewable solutions such as photovoltaic, co-generation and tri-generation from biogas.

The four generators are fed on biogas derived from agricultural biomass (such as maize, sorghum and wheat). The whole system is designed to work in balance with the plant growth cycles so that the amount of carbon dioxide emitted by combustion processes is equivalent to that absorbed by the cereals and other crops during their life cycle.

The biogas is produced by anaerobic digestion, a biological fermentation process involving microorganisms (methanogenic bacteria) that, when deprived of oxygen, transform the carbohydrates, proteins and lipids in the biomass into methane and carbon dioxide. The resulting biogas is 55% methane and is used to feed a combined heating and electricity system at each of the Bondeno generating stations.

CPL Service Manager Omar Mazzuchelli explained the process: “The biomass is fermented to release biogas which is then purified in a skid-mounted treatment system and used to power the generators to produce electricity. A transformer increases the voltage so that it can be fed into the regional supply grid.

The generating stations are each based on a SINCRO 1000 cogeneration 999kWe module driven by a Jenbacker JGS 320 GSBL gas engine. These are expected to produce a combined total of 32 million kWh and run almost continuously (at least 96% availability) with routine maintenance planned for only every 60,000 hours (seven years).

To maintain this performance level, a high degree of automation and supervision is particularly important, combining local programmable logic controllers (PLCs) with a centralised SCADA system. During the design phase of the project Alessio Vaccari, Head of the CPL Cogeneration Software Department, carried out a technical survey to evaluate the most suitable software platform to use. He chose the Movicon 11 SCADA/HMI technology, which he judged as being suitable for achieving the set objectives.

In the completed installation, each SINCRO cogeneration module is equipped with its own local PLC and touch screen control panel. These are integrated with the Movicon 11 SCADA system housed in the biopark’s on-site control centre. The local control panels communicate with their PLCs to collect all operating statuses, alarms and alerts, together with all electric power, heating and process measurements -including data on the amount of gas produced by the anaerobic digesters.

All this data is stored locally in an SQL Server database for analysing electricity yield performance trends (power, voltage, current). The SQL also logs operating parameters, such as the alternator and cylinder temperatures, water and oil temperatures, and pressures, for analysis of the plant’s physical condition.

In the control centre the main Movicon Supervisor integrates data from each local control station. This lets engineers view information on individual pieces of equipment or look at the whole operation collectively in one simple display. Data is also stored on a physical server in the control centre.

Thanks to the Movicon Data Analysis tools, the recorded measurements can be instantly extracted from the data archives and effectively represented by applying filters, zooms and other analysis functions. CLP-designed reports have been provided within the Movicon Report Designer so that bespoke data and information can be produced as required.

In addition to the statistical information, there is also an alarm management capability to automatically send notifications via SMS using GSM modems to duty operatives, managers and/or directors via the Movicon Alarm Dispatcher.

As the power plant site covers quite a large area of ground (1.2km² or nine hectares) each generator is connected to a public ADSL network using a Static IP address. Access to the supervisory system is thus possible via the internet using the built-in Movicon Web Client. For security, access to the whole control system is protected by a login procedure that assigns each person a level of access appropriate to their duties and seniority.

This web connection provides access to the system and other information, for authorised personnel, wherever they are and whenever they need it. For example, by combining dynamic HTML pages provided by the plant manufacturers with real-time operational parameter information, it allows maintenance staff to easily analyse actual usage patterns; using mobile devices from anywhere they have an internet connection.

Discussing the project delivery, Omar Mazzuchelli commented: “Because all systems were built as CPL-managed projects, we actually brought the biopark plant on stream six months ahead of schedule.”

A second objective of the project was to stimulate and secure agricultural production in the locality. This was achieved by guaranteeing biomass feedstock prices over a 15 year cycle. As a result the next generation of young farmers will be able to look forward to a stable future, so will be less inclined to migrate away from the area or out of agriculture.