What happened
Shares of Ballard Power Systems (BLDP 3.49%) are glowing green today, after the fuel cell pioneer announced an agreement to partner with commercial vehicle parts supplier Mahle to develop and commercialize "zero-emission fuel cell systems to provide primary propulsion power in various classes of commercial trucks."
Ballard stock is up 5.3% as of 1:35 p.m. EDT on the news.

Image source: Getty Images.
So what
Ballard is gaining a powerful partner in Mahle. The 100-year-old German auto parts maker semploys 77,000 workers at 60 production locations around the globe, and does about $14 billion in annual sales, producing parts that it claims are eventually incorporated into "half of all the vehicles on the world's roads."
Mahle's also been involved in supplying fuel cell vehicle parts for more than 10 years, contributing such parts as air intake systems and air filter solutions.
Now what
Ballard will be primarily responsible for designing the fuel cell stack and overall fuel cell power system, while Mahle will focus on such peripheral matters as thermal management, power electronics, and system assembly.
In its press release announcing the collaboration, Ballard said teaming up with Mahle will help it to compete for a piece of "the $100 billion annual total addressable market for commercial truck engines," and cited "EU policies ... mandating zero-emission powertrain solutions" as providing a tailwind as it enters this market.