When it comes to their impact on climate change, the conventional case in favor of natural gas trucks misses the mark. It’s time to recognize that the environmental impact of these vehicles is more nuanced than generally discussed. By examining the full impact of natural gas as a truck fuel, we can focus efforts on improving the footprint of this fuel; enabling it to live up to its environmental potential.

The conventional case looks only at what comes out of the tailpipe. But that is far from the full story. Like all fuels, natural gas has a supply chain. From the well where the fuel is produced through processing, transmission and distribution operations, small amounts of natural gas leak.  This is a problem because natural gas is largely methane – and methane is a very powerful global warming gas.  In fact, methane is 84 times more potent than carbon dioxide 20 years after it is first emitted; greater than the life span of today’s trucks.

EDF researchers published a study today in Environmental Science & Technology that explores the full lifecycle impact of natural gas trucks. They calculated that switching heavy-duty truck fleets from diesel to natural gas could lead to worse climate impacts over the next 50 to 90 years than remaining with diesel, because of the powerful effect that methane has on global warming in the near-term.

They also found pathways for natural gas trucks to achieve immediate climate benefits. To get on this path, we need to limit methane emissions from the fuel supply chain and from the vehicle; while improving the efficiency of natural gas engines relative to diesel engines.  There are two near-term policy opportunities that can help accomplish these objectives:

  • In January, President Obama announced a goal to reduce methane emissions from the oil and gas industry 45 percent by 2025. Achieving this target would reduce fuel supply chain emissions and be the most significant step we can take to improve the climate footprint of natural gas vehicles.  One crucial first step is ensuring strong US EPA methane rules for new and modified oil and gas sources, which are expected in draft form later this summer.
  • Next month, the US EPA and DOT are expected to propose new fuel efficiency and greenhouse gas standards for heavy duty trucks. Through this program, the agencies could require significant reductions of methane emissions from the tailpipes, crank cases and fuel tanks of natural gas trucks while also requiring further improvements in engine efficiency.

We all have a stake in ensuring that natural gas trucks deliver climate benefits throughout their lifetimes.  EDF is advocating for critical policy advancements because we want to see natural gas trucks deliver climate reductions. Fleets have a role to play in advancing these solutions too.  As your company adopts natural gas trucks, it should also be supporting the policies necessary to ensure these vehicles deliver on their environmental potential.