Shelley Johnson looks like the panicked face emoji. Eyes as round as a full moon, sclera visible. Eyebrows aiming to introduce themselves to her hairline. A mouth as open as an ill-fated opera singer.

A staple at ice rinks are resurfacing machines used to make clean, smooth ice for hockey, figure skating, curling and other sports. But the machines, some of which are powered by fossil fuels, can ...