“The idea for a new power plant was born in 2006 of a technical and economic necessity,” says Alto Garda Power’s CEO Giovanni Lo Presti. The paper mill Cartiere del Garda in Riva del Garda manufactures some 355,000 t of paper a year and sells it across the globe. In order to stay competitive, the paper mill had to reduce its energy costs.
At the same time, the city of Riva del Garda wanted to offer citizens a new service for reducing energy costs: district heating. They opted for a cogeneration plant for electric and thermal energy and jointly established Alto Garda Power to manage the plant, with Cartiere del Garda holding 80% of shares and Alto Garda Services AGS, the city’s public utilities, holding 20%.
From 2006 to 2008, they built the new plant based on the latest technology. The basic energy source is gas, and the heart of the system is an advanced gas turbine. The exhaust gas is collected in a recovery boiler, which produces steam fed to a steam turbine with a supply pressure of 48 bar and an exit pressure of 4 bar. The energy difference is used for producing electrical energy.
“The cogeneration plant covers the complete energy requirements of the paper mill,” states Mr. Lo Presti. “The paper mill uses 360 GWh of thermal energy, and 60 GWh are supplied to the district heating system. Moreover, we sell 50% of the electric energy to the national grid.”
Efficiency was the key word for the new plant. Maximum attention was paid to achieve the highest possible return. In 2008 the new cogeneration plant started operation and excelled due to an extremely high degree of efficiency.
“We succeeded in reaching the classification for high-efficiency cogeneration,” Mr. Lo Presti proudly points out. “Our plant has an efficiency of 83.2%. Higher values cannot be found today for cogeneration plants. We have the highest performance that can be found in similar plants.”
The new cogeneration plant enabled the paper mill to remain competitive in an unstable market. The year 2008 marked a major downturn in the paper industry, but thanks to the new plant, Cartiere del Garda did not experience the negative effects like others.
Moreover, the new plant provided palpable benefits for the environment. Due to its high efficiency, the paper mill achieved an annual decrease of some 58% in carbon monoxide and nitrogen oxide emissions, thereby achieving emission levels well below the legal standards.
High environmental quality has earned the paper mill a number of certifications, including EN ISO 14001 certification for environmental compatibility and the EMAS certification for environmental management, one of the highest possible standards in this field.
Meanwhile, the company has turned the cogeneration plant into a trigeneration plant. In 2011 an absorption chiller was installed to turn thermal energy into cooling energy. This supplies cold water for air-conditioning to both the paper mill and the utilities.
“For us efficiency is an ongoing challenge, and we continue investing in the search for maximum efficiency,” concludes Mr. Lo Presti. “It supports the manufacture of the best coated wood-free paper for offset print in the world.”