When I first entered the trucking fray in the late 1970s, I wrote about an engineering professor who was convinced that hydrogen could answer just about every need in the world of motive power. Yet here we are, almost 40 years later, with...well, not quite enough to show for it.

Hydrogen isn’t usually seen so much as a fuel but as a source of electricity by way of a chemical reaction within a fuel cell. Like the recently introduced Nikola One long-haul tractor.

Chemists and engineers are still hard at it, perhaps nowhere more so than at Ballard Power Systems in Burnaby, British Columbia. It’s been making hydrogen fuel cells for a couple of decades now, and they do have the better part of 100 city buses running on electricity derived from a fuel cell.

Some of those buses are Daimler vehicles, and the German manufacturer is at the forefront of hydrogen development. It’s certainly not alone. Honda, for example, had a fuel-cell car available for sale in 2010, said to cost $1 million to build.

Hyundai is further ahead than most others. Its European arm recently signed a deal to hand over 60 ix35 fuel cell cars to a Paris-based electric taxi startup. Already the world’s largest fuel cell taxi fleet, it uses five such cars that Hyundai delivered in 2015 and plans to have several hundred within five years.

The ix35 is said to be the world’s first mass-produced and commercially available fuel cell electric vehicle. Currently there are more than 300 of them running in 12 European countries, more than all other manufacturers combined. The car’s range is a commendable 370 miles.

There are also those who think hydrogen can be used directly as a fuel in what’s known as a Hydrogen Internal Combustion Engine. In fact one company in Delta, British Columbia, Hydra Energy, says it can convert any internal combustion engine to run on hydrogen directly, diesel trucks included, and will charge you nothing for the switchover. Users pay only a fixed long-term price for the hydrogen they use. The real key here would seem to be that Hydra doesn’t use any fossil fuels to create the hydrogen it sells. Rather, it collects ultra-low-cost waste hydrogen emanating from various common industrial plants.

The fuel cell in that gorgeous Nikola tractor, on the other hand, depends on hydrogen produced from a fossil fuel. The most common way — by far, like 95% — to make hydrogen is a process called steam reformation of methane derived from natural gas. And natural gas being just another fossil fuel, there are, of course, unwanted emissions resulting from the process.

So the Nikola tractor is not quite as clean overall as you might think. It emits nothing harmful as its electric motors buzz you down the road, just water vapor and heat, but behind the scenes a fossil fuel has been burned in order to make hydrogen. There’s still a net gain — like 20% better in terms of greenhouse gases — but it can’t be called a truly zero-emissions heavy truck.

However, Nikola says it might erect a 100-megawatt solar farm to produce electricity for conversion of water to H2 through electrolysis, thus avoiding the downside of using natural gas.

We’re getting closer. I think.