Plug Power (PLUG 1.26%) stock just keeps plugging ahead. It jumped as much as 15.5% today. Even though it pared those gains to 4.7% as of 12:15 p.m. ET, shares of the hydrogen fuel company are still about 35% higher over the past week.

Its stock has struggled over the last year, along with the stocks of other renewable energy companies. Plug's shares, though, have been hit particularly hard, as its cash reserves have been dwindling, and it announced last month that it reached an agreement with an investor to potentially issue another $1 billion worth of shares to raise capital. But a business update this week has investors thinking things may be looking up.

A milestone for green hydrogen

Today Plug Power announced its first shipment of liquid green hydrogen from its new hydrogen production plant in Georgia. The company said a truckload of liquid hydrogen was shipped from the plant to fuel forklifts for its customers Walmart, Amazon, and Home Depot.

That fuel can be used to power more than 3,200 fork trucks a day. Plug CEO Andy Marsh commented that "the first delivery of our green hydrogen molecule marks a critical milestone for the green hydrogen economy."

Importantly for the finances of the business itself, it will supplant hydrogen that Plug has had to buy on the open market at a loss to fulfill agreements with its customers. Supply chain issues delayed the start-up of its Georgia facility, and the company was forced to purchase hydrogen as the market price was spiking in recent months.

Investors should listen to the CEO

In an interview this week, Marsh admitted that the company will continue to lose money on its hydrogen shipments for several more months at least. Even as the Georgia plant ramps up, it will need several other facilities that are under construction to begin production to stem those losses.

Investors will likely hammer the stock again if it does indeed begin selling shares from the previously announced at-the-market stock offering. But Marsh said in the interview that "everybody's thinking I'm going to issue [the] common [stock], and that's probably not necessarily what we're going to do." He noted there were other options still on the table for raising capital.

That's what investors need to figure out. Marsh himself summed up the investment case nicely, stating, "If you don't believe in this [hydrogen] space, you probably shouldn't invest in this stock."