Few trucking subjects fascinate me more than the sources of motive power we’ll use in the future, and not just the distant future. The combustion engine will be with us for a long time to come, I’m convinced, but the fuel it drinks… well, that’s open to a ton of questions and possibilities.

Diesel will be king for ages, but not necessarily in a fossil-fuel form. A few years back I might have said that biodiesel – ordinary diesel blended with as much as 20% biomass-based fuel — was going to come on strong, and it looked that way at the time. I wrote a story 10 years ago on a 20-truck farm fleet that switched to biodiesel and had great success with its road equipment as well as huge combines and tractors. Fuel economy rose by 10% or so across the board, and the company was downright gleeful. They began with a 5% blend, then moved on to 20% in the summer with no ill effects.

But I went back to visit them last year, having heard that they’d abandoned the biodiesel idea. Seems their engine supplier told them if they continued, their engine warranties would be in jeopardy. The issue was essentially the lack of refining standards and the possibility of large variations in fuel quality. To my mind the idea still has merit.

We may be past that sort of blending and into direct-replacement renewables on a large scale before too long. New York City is in the process of doing exactly that. A user of biodiesel for both fueling its fleet and heating its buildings for the last dozen years, in 2019 it started moving to renewable diesel for sanitation trucks and some others. Made of plants and animal fats, the fuel is produced by Renewable Energy Group.

“Renewable diesel is an exciting next step which holds the prospect of completely replacing regular diesel with no impact to operations,” said Keith Kerman, NYC chief fleet officer.

Another good example is the City of Oakland, Calif., where waste feedstock is now being converted to renewable diesel to fuel the entire municipal fleet. San Francisco, San Diego, and Eugene, Ore. are doing the same.

Oakland and its partners gather waste cooking oils from restaurants and other businesses in the metropolitan area and convert it to fuel. It’s a low-carbon fuel that cuts engine-out emissions of nitrogen oxides by 9%, carbon monoxide by 24%, and fine particulates by 33%, and is compatible with all diesel engines. The city says it reduces greenhouse gas emissions by 74% compared to conventional fossil diesel.

Renewable diesel costs more per gallon than biodiesel, some US$1.65 more when New York made its switch, so it won’t be attractive to for-hire fleets at present. Some private freight fleets may be better able to justify it, but in the future…

And then there’s renewable natural gas (RNG) soon to be fuelling most of the 170 garbage trucks in the City of Toronto. Slated to start about now, the project will take food scraps and other organic waste, and by way of things called anaerobic digesters, turn into all that into biogas. The city is working with natural gas supplier Enbridge to accomplish this.

It’s not the first such example of such a beautiful circular solution, with garbage trucks being refueled by the waste they collect. What makes it unique, I believe, is that the gas will also be injected into the natural gas “grid” and thus used by anyone. Toronto is planning to build three more such waste-to-fuel conversion plants.

The point in all this is that, while billions are spent on battery electric and hydrogen fuel cell electric trucks, there are other short- and long-term options.