Hydrogen is one of the surprising winners in the latest version of the big Republican tax bill.

The Senate's latest rewrite of the bill offers tax credits to the industry through to Jan. 1, 2028, two years longer than the previous version. Shares of Plug Power, the largest pure-play clean hydrogen company in the U.S., soared 28.5% on Monday. Bloom Energy, which makes fuel cells that can run on hydrogen, jumped 7.8%.

Hydrogen has gained political support from some unexpected corners. Oil companies and manufacturers have lobbied in favor of the tax credits, because companies like Exxon Mobil have begun working on hydrogen as a potential clean energy source of the future.

Hydrogen can power factories and vehicles, but it's mostly made today using natural gas, a relatively dirty method. The Inflation Reduction Act introduced tax credits for cleaner versions of hydrogen, including methods that use solar and wind power to power hydrogen production, and ones where the carbon produced in the production process is captured and stored underground.

Plug Power has built hydrogen plants in Georgia and Louisiana, and sells the output to companies like Walmart. But demand has been weak, and Plug has been posting consistent losses. The stock is down 49% in the past year to a recent $1.49.

Bloom's fuel cells can run on either natural gas or hydrogen. Its customers are mostly using natural gas these days, but could switch to hydrogen if the fuel becomes cost-competitive.

Other companies that are working on producing clean hydrogen include Air Products & Chemicals and Air Liquide.