The born-again, century-old “Old Main Heating Plant” on the Minneapolis campus of the University of Minnesota is a proxy for a greener Minnesota’s economy.

That’s a job-producing, smog-reducing trend that also combats climate change that’s warming the planet and driving weather volatility.

“Old Main,” a dirty, once-shuttered, coal-fired plant, was relaunched last December as a natural gas-fired combined heat and power producer that, at 83 percent, is twice as efficient as the old facility and generates enough steam and electricity to power and heat the huge campus.

“We have lowered the campus energy bill by $2 million annually,” said Mike Berthelsen, the U’s vice president of university services, “It cuts our campus carbon emissions by 50 percent and lowers the university’s overall carbon footprint by 10 to 13 percent.”

The $113 million project is projected to easily retire the debt through energy savings over the next 25 years.

“Over 30 years, we estimate more than $150 million in savings to the university,” Berthelsen said.

That doesn’t include a $2 million rebate from a CenterPoint Energy conservation program that the U is using for campus-conservation projects.

The four-year resurrection of Old Main, including a new boiler and 22.8 megawatt turbine, was also a significant economic-development project that employed as many as 135 workers for weeks at a time. And the U no longer needs to buy electricity from Xcel Energy.

Old Main has become the base­load uninterrupted power provider for the university’s classrooms, hospital, research facilities and more; it is supplemented during winter peak-demand periods by a small gas-burning peaking facility, which also is near campus on the Mississippi River.

Green technology, from fast-growing wind and solar power, to energy-efficiency products is growing faster than the overall Minnesota economy.

Clean Energy Economy Minnesota, an advocacy group that ranges from small solar outfits to the gigantic likes of Cargill and Cummins Power, said this month that Minnesota clean-energy jobs grew 2.6 percent to 59,079 jobs last year, not counting the biofuels trade such as ethanol. That’s nearly twice the overall growth rate. And more than 40 percent of the new jobs are created outside the Twin Cities.

“Because of the state’s commitment to improving energy efficiency we are able to develop and attract talent to help us with our mission to reduce energy consumption of new and existing commercial buildings,” said Kevin Bollom, vice president of Wisconsin-based energy-equipment maker Trane, which employs 300 in White Bear Lake, including a digital studio that monitors 10,000 commercial buildings around the country. “We’re investing in new products and solutions that will help our customers reduce their energy footprint and greenhouse gas emissions.”

Minnesota’s big power generators, such as Xcel — the nation’s largest producer and buyer of wind power — and Great River Energy are producing more than 25 percent of their energy from low-carbon, declining-cost renewable forms of energy. Their carbon footprints have dropped even more over the past decade as they also have shuttered old, inefficient, dirty plants.

Utilities in the 15-state midcontinent region, including Minnesota and North Dakota, have cut carbon emissions by about 20 percent over the past decade, a trend accelerating in recent years.

The Great Plains Institute the nonpartisan clean-energy initiative, is developing with the Midcontinent Power Sector Collaborative, major and small power producers, as well as environmental stakeholders, a “road map” to power plant “decarbonization” — cutting carbon emissions by 80 percent below 2005 levels by 2050.

Xcel alone said recently: “Our goal is to reduce carbon emissions 60 percent from 2005 levels by 2030.” At the same time, it is increasing renewable-energy fuel sources from 27 percent in 2017 to nearly 50 percent in 2022, including 12 new wind farms across seven states.

Lower-cost battery storage makes it possible for power generators to store wind energy overnight for release during daytime peak demand.

Minnesota has proved we can grow by squeezing more juice out of each btu of energy, and using lower carbon sources, from natural gas to wind and solar.

“I’ve seen what this growth does for Minnesota by the number of jobs we’ve been able to create and communities we’ve been able to assist,” Eric Pasi, chief development officer of IPS Solar, the 25-year-old solar-energy contractor, said last week.

Cleaner energy and technology grow an economy less threatened by a hotter planet and billions of dollars in environmental-health costs, from childhood asthma to cancer, which is traditionally not tabulated into the real cost of carbon-based fuels and pollution.

Neal St. Anthony has been a Star Tribune business columnist and reporter since 1984. He can be contacted at nstanthony@startribune.com.