How can society meet its growing energy needs and reduce_{CO2 emissions} at the same time? The Swedish energy supplier Mälarenergi is helping to meet this challenge with its "Unit 6" waste-to-energy plant. The power plant is one of the largest of its kind in the world. Mälarenergi's waste treatment plant, boiler and chimney are located on the shores of the pristine Lake Mälar, whose crystal-clear waters stretch as far as the eye can see. Västerås, Sweden's fifth largest city with 150,000 inhabitants, lies on its shores.

Unit 6 is an efficient plant with a generation capacity of 150 megawatts per year. Of this, 50 megawatts is electricity and 100 megawatts is district heating, which can be used to heat more than 50 percent of the buildings in Västerås. The system distributes heat or hot water from a central location via insulated pipes. Numerous ABB frequency converters ensure the reliable and efficient operation of the power plant and prevent unplanned, costly downtime that could lead to a heating failure in Västerås during the long and cold Swedish winters.

"We first process the waste by removing metals, glass and any other materials that we don't want to burn in the boiler. We recycle the metal and glass and incinerate the rest to generate heat and electricity," explains Martin Eriksson, Mälarenergi Operations Manager. "This makes Unit 6 at Mälarenergi one of the most efficient and largest waste-to-energy plants in the world."

Over 200 frequency inverters installed
Almost 300 low- and medium-voltage motors and more than 200 frequency inverters from ABB are installed in Unit 6. The frequency inverters adapt the speed of the electric motors to the task at hand, which saves energy and increases performance. "Unit 6 is a very complex plant with a large number of critical components," says Eriksson. "Reliability and energy efficiency are key for us, and ABB meets our high requirements."

Mälarenergi is owned by the city and has been supplying Västerås with district heating since the 1960s. In the past, the power plant burned coal and oil until 2014, when the waste-to-energy plant was put into operation. In 2016, Mälarenergi announced its plan to phase out fossil fuels completely by 2020 to support the transition to a lower-carbon energy system. Today, Mälarenergi burns recycled wood, tree tops and waste that would otherwise end up in landfill. In this way, the company has reduced its_{CO2 emissions} from an average of 600,000 to 250,000 tons per year.

"We are delighted to be able to help Mälarenergi achieve its sustainability goals," says Anders Annell, Global Power Generation Segment Manager at ABB Motion. "This is an excellent example of how our AC drives and high-efficiency motors can increase the efficiency of applications while meeting the highest standards of reliability and safety."