As natural gas becomes more popular among fleets, some environmentalists still insist that the fuel poses greater emissions concerns than conventional fuels.As natural gas becomes more popular with fleet managers, critics contend that there are enough methane leaks associated with the alternative fuel to negate any of its environmental benefits.
Hardworkingtrucks.com contacted the Environmental Defense Fund about their concerns with natural gas and then reached out to Natural Gas Vehicles for America for a response.
Three questions were posed to EDF:
- What can you tell fleet owners and manager who are thinking of switching
to CNG (compressed natural gas)?
- What alternative fuels are you the most encouraged about?
- What’s the best way fleet owners and managers can remain informed about
 alternative fuels?
Jonathan Camuzeaux, senior economic analyst in the office of economic policy and analysis at EDF, has authored articles that raise concerns about methane emissions associated with natural gas. Camuzeaux answered the first question only.
Camuzeaux: Our study has found that given current available data, a switch from diesel to CNG fuel in trucks would on average have negative effects on the climate, unless natural gas leaks along the value chain are reduced. The findings have implications for fleet owners who look to the operational advantage in carbon dioxide emissions to justify the higher cost and reduced fuel efficiency of a natural gas truck. The challenge is that methane–the main ingredient in natural gas–has 84 times the warming power of CO2 over a 20-year time frame. Methane is released to the atmosphere at every step from production wells to the vehicle fuel tanks.
Camuzeaux (con’t): Examining a range of options, we’ve found there are indeed pathways for heavy duty natural gas vehicles to achieve climate benefits, provided methane emissions across the value chain are reduced both upstream and at the vehicle level. Otherwise, a conversion from diesel could lead to greater warming for the next 50 to 90 years before providing climate benefit. Improvements in fuel efficiency could help ensure these vehicles are climate friendly as well. Today’s CNG truck engines are typically ten to fifteen percent less efficient than diesel engines. Consuming more fuel for each mile traveled reduces the relative CO2 savings. If that efficiency gap can be closed, natural gas trucks will fare that much better compared to diesel. The opportunity is there to achieve a climate benefit, provided we address the powerful emissions both from the fuel supply system and the vehicle.
Paul Speraw, communications manager with Natural Gas Vehicles for America (NGVAmerica), responded to the following questions from hardworkingtrucks.com (HWT):
HWT: The Environmental Defense Fund and the American Chemical Association both contend that methane gas emissions associated with natural gas acquisition not only negate any benefits gained from using the alternative fuel, but are so bad on the environment that current CNG use will lead to greater global warming until these alleged methane leaks are addressed. What’s NGVAmerica’s stance on this criticism?
Speraw: We don’t agree with all of EDF’s views on this issue. We agree that NGVs are beneficial, but we disagree with their negative take on the near-term benefits of NGVs. Many of the things that EDF says must happen for natural gas to be competitive are happening already since industry is addressing upstream emissions. Using the assumptions relied upon by EPA (Environmental Protection Agency) and other organizations such as CARB (California Air Resources Board) and Argonne National Laboratory, today’s natural gas vehicles provide about a 15 to 23 percent benefit in overall greenhouse gas emissions compared to petroleum fuels. Some fleets, particularly in California, are beginning to take advantage of renewable natural gas (RNG), which is derived from landfills and other sources. GHG (greenhouse gas) emissions from RNG can be as much as 90 percent less than petroleum fuels.
HWT: There are other alternative fuels in the marketplace. What makes natural gas a good choice?
Speraw: Energy security, fuel diversity, lower cost, lower forecasted long-term costs, etc. The U.S. is the number one producer of natural gas in the world. It makes sense to build on the benefits it provides in industrial, commercial and residential applications by expanding its use in transportation, which is heavily reliant on petroleum and for which there are few viable options with respect to heavy duty on-road and off-road vehicles except for natural gas.
HWT: What are some of the latest developments in the natural gas industry that NGVAmerica is excited about?
Speraw: Several new advancements in NG (natural gas) engine technology will be entering the marketplace next year (2016; Speraw answered this question in December) including the Cummins Westport Near-Zero NOx engine. The ISL G NZ engine exhaust emissions will be 90 percent lower than the current EPA NOx limit of 0.2 g/bhp-hr and also meet the 2017 EPA greenhouse gas emission requirements. The engine will also feature a closed crank case that will further reduce engine related methane emissions by 70 percent. Technological advances in natural gas engine technology like this underline the long-term role for natural gas vehicles to reduce greenhouse gas emissions in the transportation sector.
HWT: Operational cost of natural gas vs. diesel? Versus gas?
Speraw: In addition to the lower cost of natural gas as a transportation fuel, natural gas trucks have lower maintenance costs than their diesel counterparts due to having simpler emissions control systems, given the cleaner-burning fuel.
HWT: Would you like to respond to Mr. Camuzeaux’s criticism of natural gas?
Speraw: The plain and simple fact is that as natural gas production has increased over the past decade, emissions associated with production and transmission have dropped dramatically. Upgraded pipelines, green completion programs, advancements in control devices, and state-of-the-art monitoring technology are solving the problem of these emissions. The natural gas industry has and is responsibly reducing emissions associated with producing, transporting and delivering natural gas to market.
HWT: Anything else you’d like to add?
Speraw: Natural gas is a clean-burning, low-cost, and abundant domestic energy source that is available to meet the transportation needs of fleets and consumers today. Many shippers are making the switch to natural gas to help meet their corporate sustainability goals and take advantage of lower emissions.
