Savvy readers of our articles may recall from late June that we wrote about Hyliion and their plans for the Hypertruck. Hyliion hoped to have their Hypertruck be negative emissions through the use of renewable natural gas (RNG). While the Hypertruck is not released yet, there is tangible proof now that their goal is attainable.
Driving for the Environment
The California Air Resources Board (CARB) is a regulatory body with a mission to both improve normal breathing air pollution and to reduce greenhouse gas emissions to stand against man-made climate change/global warming. They report that the energy weighted carbon intensity (CI) value of California’s natural gas vehicle fuel portfolio in the Low Carbon Fuel Standard (LCFS) program was below zero.
A CI value is a ratio of how much carbon dioxide or its equivalent in other greenhouse gases is expelled from use to the amount of energy being used. An easy way to understand this is to compare the amount of greenhouse gases made in moving a gasoline-powered car versus an electric one. An electric car may get some of that electricity fueled by burning of coal, but some is also from renewables such as solar, wind, and nuclear power, and as such the average for a kilowatt-hour of electric fuel is almost certainly inherently lower than that of a gasoline car.
CARB announced earlier this month that the CI for its LCFS program was -0.85 gCO2e/MJ, or for every one million joules of energy, a little less than the equivalent of one gram of carbon dioxide is taken out of the air.
This can mostly be attributed to the use of RNG heavy-duty and medium-duty vehicles. By using biofuels created from dairy farms and other farm facilities, the RNG vehicle packs a one-two punch: not only does it pull more energy from the natural gas before it goes into the atmosphere, but it also fulfills the job of a diesel truck and takes it off the road, a vehicle which can have a CI of about one hundred.
By combining these two factors, CARB says that while driving an RNG truck creates greenhouse emissions when looking at it in a vacuum, the effect it has on other emission-generating processes makes it a net-negative producer of greenhouse gases.
The math is further explained by the fact that methane is anywhere from 25 to 84 times more potent at contributing to the greenhouse effect, so using it to fuel a truck before it becomes a part of the atmosphere goes further than simply being more fuel efficient with diesel fuel.
A study from Gladstein, Neandross, and Associates says that due to the increasing availability of harnessing RNG from various sources, it may very well be possible for the LCFS natural gas vehicle portfolio to achieve a CI of -102, making the entire program greenhouse-neutral if half of the vehicles run on RNG.
If CARB wants to get really serious, though, it can try and focus on pushing for vehicles that run on perfluorocarbons (PFCs). PFCs have the global warming equivalent to at least 7,390x the amount of carbon dioxide. With its probably lower supply and engines’ questionable abilities to process fluorine molecules, however, this may be impractical for the short-term.