Calling it a "major part of a big puzzle," U.S. Sen. Amy Klobuchar cut the big red ribbon May 16 to introduce the new fleet of CNG buses at the Metro Bus Operations Center's CNG fueling pump in southeast St. Cloud.

CNG is short for compressed natural gas - the clean and efficient gas that will fuel the new buses. The conversion is expected to save Metro Bus $300,000 on fuel costs during the next 10 years. The buses previously ran on diesel fuel.

Klobuchar noted the natural gas is derived from the oil-and-gas production area of North Dakota, another part of the "big puzzle" that will help America develop fuels such as CNG that will be better for the environment and make the nation more energy-independent.

Many dignitaries from the greater St. Cloud area attended the ribbon-cutting ceremony, including Sartell Mayor Joe Perske and Sartell City Council member Amy Braig-Lindstrom, who is vice chair of the Metro Bus Commission.

St. Cloud Mayor Dave Kleis, also a member of the commission, served as master of ceremonies at the ribbon-cutting. Kleis noted Metro Bus is the first public-transportation agency in Minnesota to have a fleet of buses fueled by CNG. The conversion, Kleis said, was an ambitious collaborative effort among Metro Bus, Xcel Energy, the Minnesota Department of Transportation, the federal government and the four Metro Bus cities of Sartell, St. Cloud, Sauk Rapids and Waite Park. Kleis also noted that the local branch of the New Flyer company manufactured the fleet of the 23 brand-new buses.

Kleis said he hopes someday to welcome St. Joseph back as a Metro Bus member city. St. Joseph contracted for Metro Bus service a couple years ago, but the city decided to end the service because ridership wasn't up to snuff.

Kleis gave a special thanks to Klobuchar. She is the one, along with former U.S. Transportation Secretary Ray LaHood, who came to St. Cloud in 2012 to present a federal Clean Fuels grant of $3.3 million to help pay the costs of the CNG conversion. That is why Klobuchar was chosen to cut the ribbon at the ceremony.

"I'm proud to be part of this," she said, before cutting the ribbon. "It's exciting."

Other speakers included Ryan Daniels, the new president of Metro Bus, who replaced the retiring Dave Tripp; Xcel CEO Dave Sparby; Wayne Joseph, executive vice president of New Flyer; and several other officials from Metro Bus, MnDOT and the Wendal Co. of southern California, which built the fueling station.

"We at New Flyer are very proud of our products and our partnership with Metro Bus," Joseph said, noting the company employs 700 people.

Sparby said natural gas is "affordable, domestic and clean."

The total cost of the CNG conversion was about $20 million - $11.4 million for the new buses and $8 million for construction and renovation at the Metro Bus headquarters. The cost was covered by a $9.1-million Clean Fuels grant from MnDOT, the $3.3-million federal grant and from a local revenue bond.

Each new CNG bus costs $445,000, which is $40,000 more than diesel-fueled ones.

Metro Bus has a fleet of 67 buses. This year, 23 of them will be replaced with CNG buses, and eventually all of the buses will be CNG-fueled.

How it works

Natural gas, according to the U.S. Department of Energy, is an odorless, nontoxic, gaseous mixture of hydrocarbons (mainly methane) that is drawn from wells or extracted during the production of crude oil for gasoline and other products.

Because it is a gas, to store and use it, it must be stored compressed in a tank or liquefied in a storage tank by bringing the temperature down to -260-degrees F.

The compressed gas is stored at fueling pumps, such as the fueling station at Metro Bus. When a bus stops for a refueling, it's similar to re-fueling at a liquid gas pump, except a connection from the pump to the gas tank transfers the highly compressed gas into a very strong tank pressurized to several thousand pounds per square inch.

CNG is safe, according to the U.S.D.E. It has a narrow range of flammability and dissipates very quickly if released. The storage tanks are very strong and are extremely puncture-resistant, the U.S.D.E maintains.

Once compressed fuel is inside a vehicle's tank, the vehicle works much the same as it would with regular gasoline or diesel fuel. The gas mixes with air in a carburetor, then is ignited by spark plugs, producing rotational forces that make the vehicle run.

Natural gas amounts to about one-fourth of the energy use in the United States. About one-third of it is used for residential purposes and commercial uses (mainly heating and cooking); one third is used by industry; and one-third goes for electric-power production. Only about one-10th - so far - is used for transportation fuel. New technologies are expected to make compressed or liquefied natural gas more common in passenger vehicles in the future.

The U.S.D.E estimates about 100,000 vehicles in the United States and 11.2 million worldwide are NGVs (natural-gas-powered vehicles).