In Control Engineering’s global focus on manufacturing supplement (March 2008, www.controleng.com/global), Control Engineering Europe editor Michael Babb described how the European Union is focusing on lowering carbon emissions and increasing the use of renewable resources. Here he describes three efficient, sustainable energy-producing projects.

Currently under construction in one of the sunniest parts of Spain, the desert-like heights of the Sierra Nevada in Andalusia, Andasol will be the largest solar energy plant in Europe when completed in 2009. It will produce about 350 GW-hr of electricity per year, enough to power 100,000 Spanish households.

The technology captures and concentrates sunlight in two vast solar fields of trough-shaped parabolic mirrors, which track the sun and concentrate solar radiation on a collector tube installed at the focus of the mirror. Transfer fluid passing through the collector tube is heated to temperatures high enough to generate steam for conventional steam turbine generators.

The power plant is divided in two 200 hectare solar fields containing 624 parabolic troughs arranged in 156 loops. The fields produce up to twice the thermal energy that can be absorbed by the plants’ steam turbines. Excess energy is stored in liquid salt tanks for up to seven hours, thereby ensuring a continuous and stable supply of electric power.

Andasol will be the second solar energy plant in the world to use parabolic troughs to generate electricity on a commercial scale. The power plants will be controlled by ABB’s Extended Automation System 800xA and ABB Power Generation Portal software.

A typical 3 MW wind turbine can produce enough power for 3,000 average European homes, but the machines often have to be sited offshore or at remote locations to catch the best winds. This makes connection to the power grid, as well as routine maintenance, more difficult.

UK-based “npower renewables” recently signed a contract with Emerson Process Management to use Emerson’s Bristol OpenEnterprise software to connect 19 wind farms to operation centers. Emerson’s Ovation SCADA wind farm software can manage an entire fleet of wind farms or optimize operations at just one. Protective supervisory shutdown is automatically conducted when certain predefined site conditions are reached, such as excessive vibration due to high winds. The software also forecasts the production potential based on known factors, such as wind speed, wind direction and the condition of the turbine generator.

Energy conservation not only involves searching for new fuels and energy sources, but improving the efficiency of existing technology.

Arguably the largest gas turbine ever built, Siemens’ SGT5-8000H is also the most efficient. Bigger than a railroad locomotive, the 440 ton, 13m x 5m machine had to be shipped by inland waterway to the Irsching 4 test power plant near Ingolstadt (between Nuremburg and Munich, Germany), where it started its 18-month trial operation at the end of 2007. The 500 million Euro turbine will generate 530 MW with a new record peak efficiency of over 60%.

“The output of this turbine is sufficient to provide electricity for the entire population of a city the size of Hamburg [1.8 million],” said Dr. Wolf-Dietrich Kruger, head of the Gas Turbines subdivision at PG. Such engineering marvels would be impossible without extensive automation and instrument systems to monitor and control their complex operations. This one uses Siemens’ own S7-400 programmable controller-based system.