Cummins aspires to be a heavy-duty transportation propulsion leader and not just a diesel-engine giant, even if the former description takes longer to say and explain.

Thursday, Cummins (ticker: CMI) announced the production of its 100th battery-electric bus built with privately held partner Gillig . The two have been working together for years. Cummins is the one providing the battery-electric technology. Gillig builds the buses.

"This is a great milestone for Cummins, Gillig and Metro Transit, but we are just getting started," said Amy Davis, president of the new power segment at Cummins, in the company's news release. "Cummins is here to partner with customers to decarbonize and is committed to providing battery-electric solutions with the innovation, support and service that customers expect from Cummins."

The bus was delivered to Metro Transit in St. Louis.

Cummins makes high-quality diesel engines that power heavy-duty trucks and big rigs across the globe. But the company is thinking about a lower-carbon emission future too.

Thursday, the company also announced a 15-liter engine powered by natural gas. Natural gas emits less carbon dioxide than diesel fuel, for the equivalent power output. And Cummins hosted a hydrogen event in November 2020 to show investors the progress its making on hydrogen fuel-cell technologies.

Hydrogen fuel cells have potential to disrupt diesel engines. Fuel cells can generate electricity with hydrogen gas. The electricity can power electric motors. If the hydrogen gas is made from renewable-power sources, no carbon dioxide is emitted. Diesel fuel is a crude-oil derivative and emits carbon dioxide when burned. Carbon dioxide is the main gas blamed for global climate change.

Nikola (NKLA) and Plug Power (PLUG) are two companies also working on hydrogen solutions for heavy-duty trucking.

Tesla (TSLA) is making a battery-powered semi-truck. But batteries are heavy, limiting payload and range. The farther a truck needs to go, the better hydrogen solutions appear to look.

Cummins stock isn't doing much on the news. Shares are up about 0.8% in early trading Thursday. The S&P 500 and Dow Jones Industrial Average are both up about 0.9%. Alternative-fuel solutions are still businesses small for Cummins.

Cummins generated about $20 billion in 2020 sales, and didn't break out renewable power as a separate business segment.