Plug Power (NASDAQ:PLUG) are soaring today, up 28.2% as of 10 a.m. EST, after the company announced a new alliance with South Korean industrial giant SK Group last night. In a deal valued at $1.5 billion, Plug Power plans to sell a 10% stake in itself to SK Group, valuing new shares issued at $29.29 each -- but investors who already owned Plug are doing much better than that. Their shares are now worth $45.50 apiece in morning trading. Image source: Getty Images. So what Why are Plug Power investors so excited? As the company explained in last night's announcement, allying with SK Global increases its access to South Korea's "Hydrogen Economy Roadmap through 2040" plan, which envisions putting 6 million hydrogen fuel cell cars on South Korea roads over the next 20 years, building 1,200 refilling stations to fuel them, and producing 5 million tons of hydrogen fuel per year. As a maker of fuel cells and a producer of hydrogen, Plug Power is in a position to profit from at least two of the legs of this hydrogen triad -- and probably all three.