The Paris Climate Agreement says we need to reach “net zero” carbon emissions by 2050. That means for every new carbon molecule we put in the air, we have to take one out. Even the most optimistic forecasts still anticipate burning fossil fuels well past that date. So how do we balance the carbon...

Hydrogen has long been the great hope of the environmental movement. Hydrogen-powered cars; airplanes; even home heating. A single molecule could power it all. Much of that has gone nowhere. But now, hydrogen is being touted as the answer to carbon-free steel. Can we trust in our hydrogen future...