What’s more efficient, using natural gas to power an ICE vehicle, or using it to generate electricity to power an EV? A well-to-wheels (WTW) analysis by a team of researchers at the Oak Ridge National Laboratory (ORNL) has found that, with a high PTW (pump-to-wheels) efficiency and the potential for high generation efficiency with NGCC (natural gas combined cycle) turbines, natural gas is currently best used in a stationary power application for charging EVs.
However, they also noted that compressed natural gas vehicles are a viable option as well. If CNG were to be used in hybrids, the advantage of the electric generation/EV option shrinks.
Their paper, which was published in the journal Energy, notes that the efficiency with which gas is converted to electricity is a critical factor: “The most effective use of natural gas in transportation ultimately depends on the efficiency of the combustion prime mover, whether on vehicle or in a stationary power plant. The difference in WTW energy use and emissions between CNG vehicles and EVs depends on the method of producing electricity from natural gas.”
The researchers considered several different scenarios, including ones in which EVs were powered by electricity generated solely from natural gas, and ones in which the electricity came from the current US energy mix. In every scenario, they found that EVs have lower energy usage, and lower greenhouse gas emissions, than gasoline or CNG vehicles.