Omron has helped Italian waste-recycling specialist Ecodeco save more than a megawatt of power at its Corteolona plant , and reduced CO2 emissions by almost 600 tonnes per year.

At its site at Corteolona, Lombardy, Ecodeco operates a sludge treatment plant for converting urban waste into refuse-derived fuel (RDF).  RDF is a complex product which has a range of different calorific values depending on the original waste material.

After conversion, the RDF is fed into the waste-to-energy furnace using a batching system according to its calorific value. At the base of the furnace is 1.5 metres of sand which is “fluidised” by pumping air in from below: this makes the sand “boil” like a fluid, and mix with the RDF.

8.5MW generated from recycled waste

This produces a highly combustible mixture with good heat-exchange distribution, and is used to produce steam that drives a turbine generating 8.5 MW of electricity under normal conditions.

Steam leaving the turbine is forced into a cooling tower and converted back to water by a series of twelve 22kW cooling fans.  It is then returned to the waste-to-energy plant and recycled by three 160kW pumps.  Two 185kW motors are used for the boiler feed pumps and the total connected load is 1114kW.

Ecodeco wanted to reduce this electricity consumption without affecting the amount of energy produced. Omron was asked to advise on a suitable alternatives.

The solution adopted uses Omron inverters to modulate the frequencies of the different motors while maintaining pressures at a constant level. For the three recirculation pumps, and the two boiler-feed pumps, the inverters simply replaced the throttle valves.

There is no impact at all on the plant’s generating capability, but the reduction in power consumption is exceptional. Using Omron inverters reduced the annual electricity usage from 6152 MWh to 5328 MWh, saving almost 100,000 € and providing a payback time of under 13 months.

Emissions reduced by 600 tonnes

Generating one MWh of electricity by conventional methods creates 725 kg of CO2 emissions.  By cutting its annual consumption by 824 MWh, it has also reduced CO2 emissions by almost 600 tonnes.

This single project has saved energy, reduced costs, and helped to protect the environment for many years to come.

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