As cars become more energy- and emissions-efficient, so are the factories that make them. General Motors recently announced two such projects that will bring renewable energy and more sustainable operation to its Michigan automobile assembly plants.

The largest photovoltaic solar array in southeast Michigan will be built at GM’s Detroit-Hamtramck assembly plant to help power the manufacturing home of the new Chevrolet Volt electric vehicle. And when the new fuel-efficient Chevrolet Sonic and Buick Verano compact cars go into production this fall, 40 percent of the energy to power the assembly plant in Orion Township will come from burning landfill gas.

The 512-kilowatt Detroit-Hamtramck solar project will generate enough electricity to charge 150 extended-range Chevrolet Volts every day for a year. The solar array will be built on a 6-acre tract on the south side of the plant to acquire maximum sunlight. Expected to be completed by summer’s end, the 264,000-square-foot photovoltaic array will save the plant approximately $15,000 per year on electric costs over the next 20 years.

“This array will significantly decrease energy consumption by combining solar power with ongoing efficiency tactics, such as lighting and equipment upgrades and automating equipment shutdowns,” said Bob Ferguson, vice president of GM Public Policy. “Making sustainable choices is good for both the environment and our bottom line.”

Landfill gas will be used to generate steam for heat at the Orion facility as well as make compressed air for the assembly line. It is expected to save GM $1.1 million per year in energy costs as well as reduce greenhouse gas emissions.

“As we converted the facility to support the small car program, we took every opportunity to engineer in flexibility and lean manufacturing concepts,” said Eric Stevens, GM vice president of Global Manufacturing Engineering.

Lighting system upgrades at Orion saved more than 5,944 megawatts of electricity per year or $430,000 and reduced carbon dioxide by 3,676 metric tons. Workers track hourly energy consumption with software enabling real-time usage monitoring by department to improve equipment shutdowns. Natural and landfill gas heats an upgraded paint shop, which uses half of the energy per vehicle as the one it replaced. A new eco paint eliminates the need for a primer oven.

The Sonic is a turbocharged subcompact that will be available in five-door and sedan models. The Verano is a compact sedan. Production of both cars will begin this fall.