Hydrogen production is the key to the company's potential turnaround.When Plug Power (PLUG -5.25%) posted its first-quarter results, the issues that have plagued the company over the past year remained front and center. The biggest of these issues is the company's negative gross margins and cash outflows.The stock was down over 60% over the past year before news that the company received a huge $1.66 billion loan from the Department of Energy (DOE) sent shares skyrocketing higher. Let's look at its most rec ...