What happened

FuelCell Energy (FCEL -6.93%) shares zoomed this week, soaring 24.4% in the week as of 3:30 p.m. EST Friday, according to data from S&P Global Market Intelligence. There was no company-specific news or developments, so why did the fuel-cell stock gain so much in value? Thank industry developments, and rivals.

So what

FuelCell Energy shares rallied the most the very first day of the week, even hugely outperforming peers, when the passage of a much-awaited $1.2 trillion infrastructure bill sent investors in clean energy stocks into a tizzy. The bill that was passed the night of Nov. 5 proposes big spending on power infrastructure and clean energy, including $7.5 billion each on zero- and low-emission buses and ferries and on electric-vehicle charging infrastructure.

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FuelCell Energy develops carbonate fuel-cell technology to generate power and therefore primarily serves utility-scale power users. The company, however, is striving to commercialize hydrogen fuel, which is a gaining a lot of attention as an alternative zero-carbon fuel.

Just a day before the infrastructure bill was passed, FuelCell Energy used Twitter to announce its support of the bill. As that was a clear indication that the company expects to benefit under the Biden administration, investors jumped on to the stock, with optimism soaring even higher through the week after Plug Power's (PLUG -0.73%) quarterly numbers confirmed rising demand for fuel cells.

Plug Power reported strong shipments for its fuel-cell and hydrogen systems in the third quarter, generated its highest-ever revenue, and bumped up its revenue guidance for 2022. With the stock also receiving analyst upgrades this week, investors remained bullish about fuel cell stocks, including FuelCell Energy.

To be fair, Plug Power's numbers were just another trigger that helped maintain momentum in hydrogen fuel cell stocks. A much bigger factor was COP26, the mega-climate change conference held in Glasgow, Scotland, which concluded on Nov. 12. Hydrogen and fuel-cell technology were center stage at the event, with several companies and nations pledging to accelerate the use of green hydrogen as part of their efforts to decarbonize.

Now what

FuelCell Energy reported strong revenue growth for its third quarter a couple of months ago, and although the company doesn't have a product backlog yet, investor interest in the stock may not wane anytime soon, what with the rising global attention on fuel cells and the upcoming federal spending on clean energy.