When most people think of a tractor-trailer, they automatically think “diesel.” Yet that’s not always been the case. And today, we’re increasingly looking at a burgeoning range of alternative fuels and drivetrains. Exploring some of them was the goal of much of the September issue.

Looking back, however, it’s interesting to note that some of the earliest delivery trucks, in the early 20th century, were actually electric.

As the century progressed, advances in internal combustion engine technology and mass production of cheaper gasoline vehicles led to a decline in the use of electric drivetrains and to the rise of gasoline and later diesel engines for commercial trucks.

Although diesel-powered trucks were available in the 1930s, they only really started catching on as the main powerplant for trucks in the ‘50s and ‘60s, after the better highways of the new Interstate Highway System allowed trucks to run farther and longer.

The term alternative fuels first appeared in the energy literature in the late 1970s, largely as a response to concerns about the supply and price of gasoline and diesel, triggered by supply issues with Middle East crude oil.

By the 1990s, when I started covering trucking, the focus had moved more to clean air. The federal government started implementing emissions standards for diesel truck engines. Clean-air initiatives in California started targeting diesel trucks with grant programs for conversion to cleaner fuels.

In the years since, I’ve seen interest in alternatives fuels wax and wane and various alt-fuels and technologies come and go … and come around again.

Take UPS, which likes to point out it was operating electric trucks way back in the 1930s. It started using natural gas engines in 1989. By the time we entered the 2000s, its growing alternative-fuel and advanced technology fleet also included liquified natural gas, hybrids, propane, and all-electric delivery vans.

At HDT, we were reporting on all those options, as well as on biodiesel, research into algae-based diesel, dimethyl ether (DME), even early fuel-cell-electric truck efforts.

As the first decade of the 21st century went on, we saw a lot of interest in hybrids and dual-fuel trucks. The industry tried plug-in electric hybrids and hydraulic hybrids, neither of which seemed to catch on. Electric vehicles tried to make inroads in the delivery sector, with now-defunct brands such as Smith Electric, Boulder Electric Vehicle, and the short-lived Navistar eStar van.

For a while, natural gas was viewed as the main contender for a “clean” alternative fuel, pushed by T. Boone Pickens, the larger-than-life oilman-turned-natural-gas promoter. The big debate about natural gas in the early 2000s was whether compressed natural gas or liquified natural gas was best for trucking.

By 2014, however, Eaton had dropped its hydraulic hybrid and Volvo had put LNG and DME plans on the back burner.

So here we are in 2021. In addition to clean air concerns, alternative fuels and zero-emissions drivetrains are being propelled by the need to cut greenhouse gas emissions believed to be responsible for global climate change.

Battery-electric trucks have come roaring back in a big way — not only in the medium-duty/delivery business, but also for Class 8 local and regional operations. There’s a ton of R&D being poured into hydrogen fuel cell trucks. And that gas versus liquid question we saw with natural gas engines? It’s now playing out in regard to hydrogen.

Natural gas, too, is seeing a resurgence of interest, thanks to new near-zero-emissions engines and the use of renewable natural gas. We are also seeing the growth of other renewable fuels, such as renewable diesel and renewable propane autogas, to make internal combustion engines cleaner and greener. At the same time, engineers are working to make IC engines more efficient than ever.

In short, there are plenty of options for fleets looking to reduce the environmental impact of their trucks and reach sustainability goals. Some are new; some have been reborn. But unlike UPS — which has invested more than $1 billion in alternative fuels, advanced technology vehicles and fueling stations in the past 10 years — you don’t have to try them all to find something that works for your fleet.